The Epidemiology of Meningococcal Disease in New Zealand ...€¦ · Martin D, McDowell R. 2004....

The Epidemiology of Meningococcal Disease

in New Zealand in 2003

Martin D, McDowell R. 2004. The Epidemiology of Meningococcal Disease in New Zealand in 2003. Report prepared for the Ministry of Health by the Institute of Environmental Science and Research Limited (ESR). Wellington: Ministry of Health.

Published in July 2004 by the Ministry of Health

PO Box 5013, Wellington, New Zealand

ISBN: 0-478-28291-5 (Book) ISBN: 0-478-28292-3 (Web)

HP 3863

This document is available on the Ministry of Health’s Web site: http://www.moh.govt.nz

The Epidemiology of

Meningococcal Disease in

New Zealand in 2003

Prepared as part of the Ministry of Health contract for scientific services (Project C5)

By

Diana Martin Principal Scientist/

Project Leader

Rebecca McDowell Health Information

Analyst

May 2004

Client Report FW 0439

The Epidemiology of

Meningococcal Disease in

New Zealand in 2003

May 2004

Diana Martin Principal Scientist

Programme and Project Leader, Communicable Disease

DISCLAIMER This report or document (“the Report”) is given by the Institute of Environmental Science and Research Limited (“ESR”) solely for the benefit of the Ministry of Health, Public Health Service Providers and other Third Party Beneficiaries as defined in the Contract between ESR and the Ministry of Health, and is strictly subject to the conditions laid out in that contract. Neither ESR nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for use of the Report or its contents by any other person or organisation.

ACKNOWLEGEMENTS This report could not have been generated without the continuing support of staff in Public Health Services, clinical laboratories, medical practices and hospitals throughout New Zealand. All have a role in improving surveillance. The authors wish to especially thank Heather Davies, Kristin Dyet and Daniel Kay for meningococcal specialist laboratory testing; Michael Eglinton for data integration, Carol Kliem and Trev Margolin for assistance with surveillance, Ruth Pirie for the maps and David Phillips and Fiona Thomson-Carter for peer review.

TABLE OF CONTENTS

EXECUTIVE SUMMARY .............................................................................................................................................. 1

INTRODUCTION ............................................................................................................................................................ 2

METHODS........................................................................................................................................................................ 2 A. SURVEILLANCE METHODS.................................................................................................................................... 2 B. LABORATORY METHODS...................................................................................................................................... 5

RESULTS.......................................................................................................................................................................... 6 1. INCIDENCE AND DISTRIBUTION ................................................................................................................................ 6

1.1. Incidence by year and month .......................................................................................................................... 6 1.2. Incidence by place .......................................................................................................................................... 9 1.3. Incidence by age ........................................................................................................................................... 12 1.4. Incidence by DHB and age group................................................................................................................. 14 1.5. Incidence by ethnicity ................................................................................................................................... 14 1.6. Incidence by DHB and ethnicity ................................................................................................................... 16 1.7. Incidence by gender ...................................................................................................................................... 17 1.8. Incidence by deprivation (NZDep2001)........................................................................................................ 17

2. BASIS FOR DIAGNOSIS............................................................................................................................................ 19 2.1. Clinical description....................................................................................................................................... 19 2.2. Confirmation of disease based on laboratory testing. .................................................................................. 19 2.3. Impact of pre-hospital antibiotic treatment on confirmation of disease by culture ...................................... 20 2.4. Geographical, ethnic and age group disparities in the confirmation of disease .......................................... 21 2.5. Confirmation of disease by PCR testing following antibiotic usage............................................................. 21 2.6. Characteristics of meningococci causing New Zealand’s disease................................................................ 23 2.6.1. Cases confirmed by isolation of a meningococcus.................................................................................... 23 2.6.2. Cases confirmed by PCR alone................................................................................................................. 24 2.6.3. Overall Burden of Disease........................................................................................................................ 24 2.6.4. Meningococci associated with fatal cases ................................................................................................ 25 2.7. Antimicrobial susceptibility .......................................................................................................................... 25

3. CLINICAL OUTCOME .............................................................................................................................................. 26 3.1. Case-fatality.................................................................................................................................................. 26

4. CASE MANAGEMENT.............................................................................................................................................. 27 4.1. Hospitalisation.............................................................................................................................................. 27 4.2. Pre-hospital visit to doctor and antibiotic treatment .................................................................................... 27 4.3. Pre-hospital antibiotic treatment by age group ............................................................................................ 29

5. RISK FACTORS ....................................................................................................................................................... 29 5.1. Contact with case.......................................................................................................................................... 29

DISCUSSION.................................................................................................................................................................. 31

APPENDIX...................................................................................................................................................................... 34

REFERENCES ............................................................................................................................................................... 47

Executive summary Introduction ! Reviews of meningococcal disease epidemiology in New Zealand have variously been

published since 1991. This report provides 2003 data and some comparative historic data. Surveillance methods ! Surveillance of meningococcal disease is based on the combination of disease notification and

laboratory data. Isolates and/or meningococcal DNA from cases of disease are fully characterised enabling monitoring and reporting of disease incidence by group or strain type.

Incidence and distribution ! A total of 541 cases of meningococcal disease were notified in 2003 of which 388 were

laboratory confirmed. The incidence rates were 14.5 per 100 000 and 10.4 per 100 000 respectively. The total number of cases since the start of the epidemic in 1991 is 5293, with 216 deaths recorded, a case fatality rate of 4.1%.

! The highest case numbers have consistently been in the upper North Island, particularly in the

Counties Manukau, Auckland and Waitemata District Health Boards, with rates for Counties Manukau consistently among the highest nationally.

! The highest age-specific rates of disease continue to be in children less than 5 years of age, with

those less than one year having a rate of 124.4 per 100 000 and 1-4 year olds a rate of 59.7 per 100 000. The correlation between age of less than 5 years and increasing deprivation was again shown in 2003.

! Ethnicity based age-standardised rates have varied from year to year although following a

similar pattern. In 2003, the rates for Pacific Peoples and Maori were 3.8 and 2.2 times higher than those of European ethnicity. The median age for Maori has increased over the last three years, from 2.6 years in 2001 to 5.2 years in 2003.

! The importance of PCR as a means of confirmation of disease has again been shown in 2003.

Use of PCR increased the confirmation rate by 36.6% (142/388). Geographical disparity in the use of PCR impacts on confirmation rates particularly in areas with highest disease numbers.

! The epidemic group B strain with PorA type P1.7b,4 continues to dominate disease patterns

with 88.9% (177/199) of group B isolates and 77.4% (82/106) of PCR positive specimens defined as the epidemic type. Group C meningococci represented 12.4% of cases (45). A noticeable but small increase in cases with W135 or Y meningococci occurred in 2003.

Discussion and implications ! Accurate disease surveillance data including evidence of disease confirmation are vital for the

evaluation of vaccine effectiveness. The established robust historical dataset provides the information against which changes in disease epidemiology and vaccine effectiveness can be made.

The Epidemiology of Meningococcal Disease 1 May 2004 in New Zealand in 2003

Introduction New Zealand’s epidemic of serogroup B meningococcal disease began in mid-1991. The epidemiology of this disease in New Zealand has been summarised annually and described in several publications. 1-17 The aims of this report are to describe the epidemiology of meningococcal disease in 2003 and to review the trends in disease patterns particularly from 1999 through 2003, a period during which data has been more consistently collated. In mid-2002 vaccine trials aimed at measuring immunogenicity and the safety of a ‘tailor made’ vaccine targeting New Zealand’s epidemic ‘strain’ were started. Providing regulatory approval is given, the Meningococcal Vaccine Strategy aims to provide the MeNZBTM vaccine to everyone under 20 years of age progressively starting from mid-2004. This report provides historic and recent data against which the effectiveness of the vaccine campaign can be assessed.

Methods

A. Surveillance methods Surveillance of meningococcal disease in New Zealand is based on a combination of notification and laboratory data (Figure 1). Meningococcal disease is notifiable to Medical Officers of Health under the Health Act 1956. Data on each case are recorded onto a computerised database (EpiSurv), which is installed in all Public Health Services (PHSs). These data are sent to ESR each week and collated on behalf of the Ministry of Health. Both patient specimens and meningococci or meningococcal DNA obtained from cases of disease are referred to the Meningococcus Reference Laboratory at ESR for confirmation of disease and for characterisation of the invading strain. Additionally, results from any diagnostic testing undertaken in clinical laboratories are actively sought for all notified cases. This information combined with group, PorB type (serotype) and PorA type (subtype), determined at ESR on isolates and identity of meningococcal DNA from patient specimens, are entered into a laboratory database and merged with the EpiSurv database to provide a more complete picture of the disease epidemiology. SAS (v 8.2) was used to analyse the combined dataset. All maps were produced using ArcView 8.3.


Figure 1. New Zealand meningococcal disease surveillance system, showing main information flowsand integration of laboratory and notification information sources

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As for all notifiable diseases, rate calculations for different ethnic groups used a prioritised approach to allocate ethnicity. The EpiSurv system specifically allows mixed ethnicity reporting for all diseases. Using the prioritised approach, anyone who self-identified as Maori (either ‘sole-Maori,’ or Maori and one or more other ethnicities) was included in the Maori ethnicity group. Similarly, anyone who identified themselves as a Pacific person was included in the Pacific ethnic group, unless they also identified themselves as Maori, in which case they were included in the Maori ethnic group. The use of mixed ethnicity classification, rather than sole ethnicity, is likely to produce lower estimates of the rates of disease in Maori and Pacific populations. This is because compared with the census (denominator) data, disease notification data, along with all health data, are disproportionately more frequently coded with a sole rather than mixed ethnicity classification. For the purposes of this report, an associated case is defined as any case for whom the onset of symptoms in the index case was within 60 days of the onset of symptoms in the associated case. Cases occurring on the same day or within one day of the index case are classified as co-primary associated cases.18-21 Notification data are based on information recorded on EpiSurv as at 9 February 2004. Any changes made to EpiSurv data by PHS staff after this date will not be reflected in this report. Disease rates were calculated using 1991 population census data as the denominator for the 1990-93 period, 1996 population census data as the denominator for the 1994-2000 period, and the 2001 population census data as the denominator for 2001 to 2003. Shifts in the demographics of the New Zealand population mean the accuracy of these data in representing the true population rates lessen as the years progress. Until 2002 all rates were calculated by Health District. The 2002 report provided information by Health District and by District Health Board. This 2003 report provides data calculated only by District Health Board. Numbers are included in the report to highlight the geographical burden of disease which may not be usefully represented by rates alone. The Epidemiology of Meningococcal Disease 3 May 2004 in New Zealand in 2003

This report also analyses the distribution of meningococcal disease by deprivation using the NZDep2001 index of deprivation. This index, measuring relative socioeconomic deprivation, is derived from a weighted combination of nine variables (from the 2001 Census), each reflecting a different aspect of material and social deprivation. The deprivation score, which ranges from 1 (least deprived) to 10 (most deprived), is calculated for each meshblock in New Zealand. Approximately equal numbers of people reside in areas associated with each of the ten deprivation levels.22 Case definition The case definition in the Ministry of Health’s Communicable Disease Control Manual 23 is ‘meningococcal disease presents as meningitis or meningococcal septicaemia. The disease presents as an acute fever, nausea, vomiting, and headache, that may progress rapidly to shock and death. Petechial rash is seen in about 50 percent’. Cases with a clinically compatible illness are classified as confirmed or probable as follows: Confirmed case: A clinically compatible illness with at least one of the following: • isolation of Neisseria meningitidis from an otherwise sterile body site (blood, CSF, aspirate or

skin biopsy); or • a positive nucleic acid test (NAT) using polymerase chain reaction (PCR) on CSF, blood,

serum, or aspirate; or • detection of Gram-negative intracellular diplococci in CSF, aspirate or skin biopsy; or • positive meningococcal antigen test on CSF. Probable case: • a clinically compatible illness and isolation of N. meningiditis from the throat; or • a clinically compatible illness.


B. Laboratory methods All meningococci isolated from notified cases of meningococcal disease are referred from diagnostic laboratories in New Zealand to the Meningococcus Reference Laboratory at ESR. Identity of isolates is confirmed and serogrouping, serotyping and serosubtyping undertaken on all isolates. Genetic typing using restriction fragment length polymorphism (RFLP) analysis of isolates is carried out for the purposes of defining clusters. Serogrouping, which defines the capsular antigenic type of isolates, is undertaken by the slide agglutination technique using commercial antisera specific for serogroups A, B, C, X, Y, Z, W135 and 29E. Serotyping, defines the PorB outer membrane protein (OMP), and serosubtyping, defines the PorA OMP. These are determined on isolates using the whole cell ELISA method.24 Monoclonal antibodies (RIVM, The Netherlands) used are: 1, 2a, 2b, 4, 14 and 15 for serotyping; and P1.1, P1.2, P1.4, P1.5, P1.6, P1.7, P1.9, P1.10, P1.12, P1.13, P1.14, P1.15 and P1.16 for serosubtyping. When isolates are not subtypable using monoclonal antibodies, DNA from the isolate is extracted and amplified using the porA-PCR test. DNA-DNA hybridisation using sequence-specific probes enables identification of the DNA encoding the PorA subtype.25 Unusual results are investigated using sequencing analysis. Samples of blood, CSF and tissue aspirates, or extracted DNA, received for confirmation of disease by PCR are also characterised to determine the strain type. The porA-PCR test is used to confirm the presence of meningococcal DNA in these specimens. Sequencing analysis is used to define the PorA subtype as is done for isolates. Additionally the siaD-PCR test is used to determine the capsular group.26


Results

1. Incidence and distribution

1.1. Incidence by year and month In 1990, prior to the start of the current epidemic, 53 cases of meningococcal disease were notified in New Zealand. From 1991 case numbers increased peaking at 613 in 1997. From 1998 to 2002 an average of 526 cases per year were notified, with the 650 cases notified in 2001 the highest since the start of the epidemic (Figure 2). In 2003, a total of 541 cases of meningococcal disease were notified, a rate of 14.5 per 100 000 population. This rate is slightly less than that for 2002 (14.9 per 100 000 population, 557 cases) yet still approximately ten times higher than the rate of 1.5 per 100 000 population occurring in the immediate pre-epidemic years (1989-90). Of the 541 cases in 2003, 388 (71.7%) were confirmed, giving a rate for confirmed cases of 10.4 per 100 000.

Figure 2: Confirmed and probable meningococcal disease cases,1990-2003

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When the annual number of cases in New Zealand for the period 1989 –2003 (including the two years preceding the increase in disease) is overlaid on the published numbers for Norway 27 1971 through 1990, the shape of the two epidemic curves appears similar (Figure 3). The total number of cases reported since the epidemic began in New Zealand is 5293. This total is an excess of 4630 cases over the number that would have occurred had the pre-epidemic incidence rate of 1989-90 (average of 51 cases per annum) continued. On the basis of Figure 3, without intervention the epidemic is predicted to continue for at least another 10 years, with the possibility of another 4000-5000 cases and 200 deaths.

Figure 3: Meningococcal disease cases by equivalent year for Norway and New Zealand

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Throughout the epidemic the greater number of cases of disease have occurred in the winter/spring months (June through November), though the exact winter peak varies from year to year (Figure 4). In 2003, the number of cases increased each month from March until July, then dipped in August but rose again in September before decreasing each month until the end of the year. In 2003, 63.6% of cases (344/541) occurred in the winter and spring months. When analysed by month of disease occurrence and age (<5 years and >5 years), a slightly higher percentage of the cases aged less than five years occurred in the winter and spring months; 66.0% compared to 62.2% for cases aged five years or over. This is in contrast to the previous three years where there was a higher proportion of cases aged five years or greater in the winter and spring months (Figures 5 & 6).


Figure 4: Meningococcal disease cases by month,1999-2003

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Figure 5: Meningococcal disease cases <5 years by month,1999-2003

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Figure 6: Meningococcal disease cases > 5 years by month,1999-2003

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1.2. Incidence by place In 2003, as in previous years, there was a marked geographic variation in the number of notified cases and rates of meningococcal disease (Figures 7-10). DHBs in 2003 with rates higher than the national average were; Counties Manukau (28.5 per 100 000 population), Whanganui (28.3), Lakes (27.1), Northland (26.4), Bay of Plenty (24.1), and Auckland (18.5). The lowest rates were from Nelson Marlborough DHB (0.8 per 100 000 population) and West Coast DHB (3.3) each with only one notified case. As in 2002, Nelson Marlborough was the only District Health Board to have a rate of disease comparable with rates observed in most industrialised countries of the world. Note that in DHBs where populations are small the rates can vary markedly from year to year. Case numbers by DHB are presented in Appendix Tables 11 and 12. When the number of notifications over the last five years are summarised, Counties Manukau has had over 200 more cases than the next highest DHB (549 cases versus 338 for Auckland DHB over the five year period). The northern DHBs (Northland, Waitemata, Auckland and Counties-Manukau) continued to have many fewer cases of disease laboratory confirmed. The proportion of unconfirmed cases in Northland (45.9%), Waitemata (43.6%), Auckland (50.0%) and Counties-Manukau (39.3%) contrasted with Waikato (2.4%), Capital and Coast (4.8%) and Canterbury (12.1%) for example.


Figure 7: Meningococcal disease cases by District Health Board,2003

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Figure 8: Meningococcal disease rates by District Health Board,2003

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Figure 10: Meningococcal disease rates per 100 000 by District Health Board, 1999-2003

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1.3. Incidence by age As in previous years, in 2003 the highest age specific rates were aged less than one year (124.4 per 100 000 population) and 1-4 years (59.7 per 100 000 population). However, the percentage of cases aged less than five years was only 36.4% compared to 42.9% in 2002. The percentage of cases aged less than five years has decreased each year since 1999 when cases in this age group represented 56.7% of total cases (Figure 11). [Appendix: Tables 13-16.] In 2003, 45.6% (31/68) of infants aged under one year were less than six months old at the time of disease. This was slightly lower than the average 49.5% (191/386) of cases occurring in the period 1999-2002 (inclusive).


Figure 11: Meningococcal disease rates by age group, 1999-2003

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Analysing by single year of age (Figure 12) illustrates the distribution of cases within narrow age bands, and across the age span. The secondary peak during the late teenage years, especially amongst those aged 18 years is particularly notable. In 2003 there were 31 cases aged 18 years (5.7% of total cases), an increase of over 60% from the 19 cases at this age in 2002. Cases aged 18 years represented, on average, 3.1% of total cases for the years 1999-2002. Thirty nine percent (12/31) of the 2003 cases aged 18 years were in the South Island (Otago 6 cases, Canterbury 5 and Southland 1), compared to only 13.3% of the total 2003 cases. Incidence by DHB and age group is explored further in the next section. Twenty-nine of the thirty-one 2003 cases aged 18 years were confirmed of which 22 (75.9%) were group B and 7 (24.1%) were group C. Those 20 years or over, accounted for 26.6% of the cases.


Figure 12: Meningococcal disease cases by age, 2003

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1.4. Incidence by DHB and age group Rates by DHB and age group (0-4 years, 5-19 years and 20+ years) are presented in the Appendix: Table 17. Nationally, the 0-4 year rate was just over three times greater than the 5-19 years rate. DHBs with a greater rate differential between these two age groups included MidCentral, Hawke’s Bay, South Canterbury, Taranaki and Counties Manukau. Noticeably, Otago and Southland DHBs were not consistent with this trend. These two DHBs had higher rates for the 5-19 year age group (1.9 and 1.6 times respectively). Of the 14 Otago DHB cases aged 5-19 years, 12 were aged between 16 and 19 years with six of these aged 18 years. Cases aged 18 years represented 26.1% of the total cases in the Otago DHB compared to 5.7% of the total cases nationally. Rates for the 20+ age group were comparatively low when compared to the other two age groups. DHBs with a rate for this age group greater than 10 per 100 000 population were Bay of Plenty (18 cases) and Tairawhiti (3 cases).

1.5. Incidence by ethnicity Over the last five years the age-standardised rates by ethnicity for meningococcal disease has remained fairly constant, with the exception of that for Pacific Peoples (Figure 13). The age-standardised rate for Pacific Peoples increased from 1999 to 2001 before decreasing noticeably in 2002. In 2003, the rate increased again to be just above the rate seen in 1999. The age-standardised rates for Maori and Pacific Peoples continue to be higher than that for Europeans. In 2003 the age-standardised rate for Maori was 2.2 times the rate seen in the European population, a slight increase over that which occurred in 2002 (1.7). The 2003 rate for Pacific Peoples was 3.8 times that for those of European ethnicity, an increase from the 2.4 times difference seen in 2002, when the age-standardised rate for Pacific Peoples noticeably decreased.


Figure 13: Age standardised rates for meningococcal disease cases by ethnicity, 1999-2003

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In all ethnic groups rates of disease were particularly high among those under five years of age (Figure 14). The highest rate observed was in Pacific children under one year of age (504.2 per 100 000 population). This rate is noticeably greater than the equivalent rate of 368.4 per 100 000 population in 2002 but less than the rate in 2001 (639.9 per 100 000 population). Among those aged less than 10 years, the rates for Pacific Peoples were significantly higher (chi-square = 271.58, p<0.0001) than those experienced by the European population. The rates for Maori people were also significantly higher (chi-square = 114.54, p<0.0001) when compared with the European population. [Appendix: Tables 18-21.] The median age for cases of meningococcal disease by ethnicity are markedly different, being 5.2 years for people of Maori ethnicity, and 2.8 years for Pacific Peoples compared with 18.5 years among the European population. While the Pacific Peoples and European median ages are similar to previous years, the median age for Maori is noticeably higher at 5.2 (cf 2.9 years in 2002 and 2.6 years in 2001). Maori cases aged less than five years only accounted for 48% of total Maori cases in 2003, compared to an average of 63% over the past four years (1999-2002).


Figure 14: Meningococcal disease rates by age group and ethnicity, 2003

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1.6. Incidence by DHB and ethnicity Numbers and rates for cases of meningococcal disease by DHB and ethnicity are presented in the Appendix: Table 22 and summarised in Figure 15 below. European rates were highest for Lakes (28.6 per 100 000 population, 16 cases) and Bay of Plenty (22.7 per 100 000 population, 28 cases), although Waitemata had the greatest number of European cases (34). The greatest number of Maori cases was notified from Counties Manukau (35 cases) and Northland (26 cases) DHBs. The corresponding rates for these two DHBs were in the top three (57.0 and 63.8 per 100 000 population respectively) but Whanganui had the highest actual rate (85.1 per 100 000 population, 12 cases). By far the greatest number of cases in Pacific Peoples occurred in Counties Manukau (55 cases) and Auckland (31) DHBs. Cases of Pacific People ethnicity were notified from nine other DHBs but all had less than 10 cases.


Figure 15: Meningococcal disease cases by Ethnicity and District Health Board, 2003

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1.7. Incidence by gender As in previous years (1999-2002), the rate of meningococcal disease has been similar among males and females. [Appendix: Tables 23 & 24.]

1.8. Incidence by deprivation (NZDep2001) Figure 16 illustrates the association between rates of meningococcal disease and deprivation in New Zealand. This uses the NZDep2001 decile scale, with 1 representing the least deprived and 10 representing the most deprived score. Note that analysis has only been performed on notified cases whose addresses geocoded to at least ‘Street’ level (532/541, 98.3%). As in 2002, rates in the ‘less than 5 years’ age group were found to increase rapidly with increasing deprivation. This association was less apparent in children aged between 5 and 14 years, and not at all apparent in young adults.


Figure 16: Rates of meningococcal disease by age group and associated index of deprivation, 2003

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The association between rate of disease and deprivation varied considerably throughout the country and was more apparent in North Island than South Island District Health Boards. Figure 17 illustrates the trend for each island and selected DHBs.

Figure 17: Rates of meningococcal disease in selected District Health Boardsby associated index of deprivation, 2003

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South Island DHBsNorth Island DHBsWaitemataWaikato


2. Basis for diagnosis

2.1. Clinical description In 2003, information on clinical presentation was available for 526 (97.2%) of the 541 cases. This is slightly higher than the 92.3% (514/557) recorded for cases in 2002. A petechial or purpuric rash was the most common clinical description recorded in 2003, followed by septicaemia and meningitis (Table 1). There were 2 cases with septic arthritis; other unusual presentations included conjunctivitis (n=2), osteomyelitis (n=2), pneumonia (n=1), and arthralgia (n=1). In six instances no information was provided of the case having had meningitis, septicaemia, petechial rash or other invasive illness. Five of these six cases were laboratory confirmed, three by culture of a meningococcus and two by PCR. The remaining case had a positive throat isolate. Table 1. Recorded clinical description for meningococcal disease cases, 1999-2003

1999 2000 2001 2002 2003 Clinical description No. %1 No. %1 No. %1 No. %1 No. %1 Meningitis 242 49.8 255 55.8 297 50.9 247 48.1 258 49.0 Septicaemia 218 44.9 198 43.3 307 52.7 273 53.1 313 59.5 Petechial or purpuric rash 373 76.7 335 73.3 443 76.0 372 72.4 390 74.1 Septic arthritis 0 0.0 0 0.0 0 0.0 2 0.4 2 0.4 Total cases where clinical description was recorded

486

100

457

100

583

100

514

100 526 100

1 Percentage (%) of total cases for whom clinical details were recorded

2.2. Confirmation of disease based on laboratory testing. In 2003, 71.1% (388/541) of cases were laboratory-confirmed, slightly lower than the figure of 74.1% in 2002. Since 1994 when pre-hospital administration of antibiotics was actively promoted, there has been a reduced chance of obtaining culture-positive meningococcal disease cases. This has been compensated for by use of PCR which was introduced in 199623 but the acceptance of the use of this laboratory test has been slow. In 2003, 142 cases (26.2%) of meningococcal disease, not confirmed by isolation of a meningococcus, were confirmed by detection of meningococcal DNA from sterile site specimens. Table 2 presents the basis of confirmation in a hierarchical system where each case is represented in the table only once, starting with the isolation of N. meningitidis from CSF, blood or other sterile site down to a positive result in the latex meningococcal antigen test. Recovery of meningococci from the throat provides presumptive evidence only and the case is therefore categorised as probable. DNA from one PCR positive case was received at ESR after the analysis in this report was undertaken. This case is therefore not represented in the dataset as a confirmed case.


Table 2. Meningococcal disease, basis for diagnosis, 1999-20031 1999 2000 2001 2002 2003 Basis for diagnosis No. % No. % No. % No. % No. % Isolation of N. meningitidis from blood and/or CSF or any other sterile site

243

48.2

256

53.3

319

49.1

229

41.1

242

44.7

PCR test 72 14.3 83 17.3 159 24.5 177 31.8 142 26.2 Gram-negative diplococci in CSF

17 3.4 8 1.7 11 1.7 7 1.3 4 0.7

Meningococcal antigen test

1 0.2 1 0.2 0 0.0 0 0.0 0 0.0

Confirmed –subtotal 333 66.1 348 72.5 489 75.2 413 74.1 388 71.7 Clinical criteria and a positive throat swab

7 1.4 2 0.4 4 0.6 4 0.7 6 1.1

Clinical criteria 164 32.5 130 27.1 157 24.2 140 25.1 147 27.2 Probable –subtotal 171 33.9 132 27.5 161 24.8 144 25.9 153 28.3 Total 504 100 480 100 650 100 557 100 541 100

1 Each case is represented only once in the table.

2.3. Impact of pre-hospital antibiotic treatment on confirmation of disease by culture Data showing the impact of pre-hospital antibiotic treatment on the isolation of viable organisms from blood, CSF and other normally sterile sites on admission to hospital for 2003 is given in Table 3. An organism was isolated from only 24.6% of cases treated with antibiotics prior to sampling, compared with 51.9% of cases who did not have antibiotics given. This difference was statistically significant (chi-square = 29.41, p<0.0001) and follows the trend shown for the years 1999 through 2002 (Table 4). These results illustrate the impact of the use of antibiotics to eliminate meningococci for suspected cases of disease. Table 3. Pre-hospital antibiotic treatment and isolation of viable organisms from cases of meningococcal disease, 2003 IV/IM antibiotics prior to hospital admission

Viable organism isolated

From case

No organism isolated

from case

Isolation rate (%)

Total Yes 32 98 24.6 130 No 210 195 51.9 405 Not recorded 0 6 0.0 6 Total 242 299 44.7 541


Table 4. Pre-hospital antibiotic treatment and isolation of viable organisms from cases of meningococcal disease, 1999-2003

Isolation rate (%) / Number IV/IM antibiotics prior to hospital admission

1999 (n=504)

2000 (n=480)

2001 (n=650)

2002 (n=557)

2003 (n=541)

Yes 22.1/30 37.6/38 30.4/41 31.3/36 24.6/32 No 58.9/179 58.1/176 56.1/258 45.0/187 51.9/210

Not recorded 53.1/34 55.3/42 36.4/20 23.1/6 0.0/0

Total 48.2/243 53.3/256 49.1/319 41.1/229 44.7/242

2.4. Geographical, ethnic and age group disparities in the confirmation of disease Geographical differences in the proportion of total cases laboratory confirmed occur. In 2003, less than 60% of cases from Auckland, Northland and Waitemata DHBs were confirmed. DHBs with 10 or more cases and a confirmation rate above 90% included Waikato, Capital and Coast, Whanganui, Hutt and Southland. [Appendix: Table 25]. The highest percentage of confirmed cases in 2003 occurred among the 15-19 and 20-29 year age groups (87.1% and 84.1% respectively) and the lowest among the 1-4 and 5-9 age groups (58.9% and 65.2% respectively). This is consistent with the observation that since 1996, cases <10 years of age have been confirmed less often [Appendix: Table 14]. In 2003, confirmation of disease was highest for European cases (80.0%) throughout New Zealand, lower for Maori (71.9%) and lowest for Pacific peoples (52.2%). This trend was consistent in the years 1999 through 2002. [Appendix: Table 19]. 2.5. Confirmation of disease by PCR testing following antibiotic usage Table 5 shows that the percentage of confirmed cases given pre-hospital antibiotic treatment was highest for cases confirmed by PCR alone (36.7%). These results demonstrate the value of PCR testing in cases when antibiotics have been given prior to sampling because of the difficulty of obtaining a viable culture after antibiotic treatment.


Table 5. Pre-hospital antibiotic treatment of meningococcal disease cases by basis of laboratory confirmation, 2003 No. Pre-hospital antibiotic treatment Basis of diagnosis1 Of cases Yes No Unknown % treated2

Isolation of N. meningitidis from blood and/or CSF or any other normally sterile site 242 32 210 0 13.2 PCR 142 51 88 3 36.7 Gram-negative diplococci in CSF 4 0 3 1 0.0 Meningococcal antigen test 0 0 0 0 N/A Confirmed –subtotal 388 83 301 4 21.6 Clinical Criteria and a positive throat swab 6 1 5 0 16.7 Clinical criteria only 147 46 99 2 31.7 Probable –subtotal 153 47 104 2 31.1 Total 541 130 405 6 24.3 1 Each case is represented only once in the table 2 Percentage (%) of cases for whom this information was available Figure 18 presents the differences in confirmation methods by District Health Board. Counties Manukau and Bay of Plenty had the greatest number of cases confirmed by PCR alone (22 and 21 respectively). However, while the number of cases confirmed by PCR alone for Bay of Plenty represented 48.8% of all the cases for that DHB, the 21 cases for Counties Manukau represented only 20.6% of its total notified cases (39.3% of cases for this DHB were unconfirmed). Other DHBs with between 40-50% of total cases confirmed by PCR alone included Lakes (50.0%), Tairawhiti (50.0%), Hutt (46.2%) and Whanganui (44.4%). DHBs with less than 20% of all cases confirmed by PCR (where the number of cases exceeded 10) included Northland (10.8%), Otago (13.0%), Auckland (13.2%), Hawkes Bay (16.7%) and Waitemata (18.2%). [Appendix: Table 25] Appendix Tables 26 and 27 present the percentage of cases confirmed by PCR and other means by DHB and age group and DHB and ethnicity. As the PCR test for meningococcal DNA may be positive even when meningococci are not viable, further increase in the use of this test would allow for greater confirmation of meningococcal disease cases.


Figure 18: Meningococcal disease cases by District Health Board for PCR and other means of confirmation, 2003

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Confirmed by PCR

Confirmed by means other than PCR

Probable

2.6. Characteristics of meningococci causing New Zealand’s disease

2.6.1. Cases confirmed by isolation of a meningococcus The increase in disease rates since 1991 has largely been attributable to serogroup B meningococci expressing the PorA P1.7b,4 protein. Serogroup B disease, particularly that caused by the epidemic type, continued to dominate in 2003. Of the isolates obtained from cases 82.2% (199/242) were serogroup B and of these 177 (88.9%) were the epidemic type. This was similar to 2001 (92.9%; 262/282) and 2002 (92.0%; 173/188). Since 1995 greater than 85% of all serogroup B disease has been caused by this type. The continuing dominance of the epidemic type with respect to all disease regardless of serogroup is demonstrated in Figure 19. Since 1991 the proportion of cases caused by serogroup C has varied in relation to serogroup B with W135 and Y serogroups uncommon in New Zealand (Figure 19). During 2000, only 10 (3.9%) cases were caused by serogroup C. From 2001, a small resurgence of cases caused by serogroup C occurred particularly in Otago. In 2002, 35 (15.5%) cases of group C were identified throughout New Zealand with 13 from the Otago District Health Board. In 2003, 31 isolates of serogroup C were obtained of which six were from the Otago District Health Board and eight were from the Canterbury District Health Board. Most noticeable was the increase in cases involving serogroup W135. Seven W135 cases and five Y cases were identified in 2003. The reason for this increase is unknown.


Figure 19: Meningococcal disease isolate serogroup and dominant subtype, 1990-2003

0

50

100

150

200

250

300

350

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

Num

ber o

f iso

late

s

OtherSerogroup CSerogroup B, otherSerogroup B with P1.4 subtype

2.6.2. Cases confirmed by PCR alone A total of 143 cases was confirmed only by a positive PCR test performed either at a regional hospital or at ESR. This total includes the PCR positive case for whom DNA was submitted to ESR in 2004. Not all specimens obtained from PCR positive cases in regional laboratories were able to be confirmed at ESR. Genotyping using the siaD PCR showed that 88.3% (106/120) encoded the group B capsular polysaccharide and 11.7% (14/120) encoded the C polysaccharide. A further 14 were unable to be defined by group PCR. Of those genotyping as group B, and for which a PorA positive PCR was obtained 77.4% (82/106) were shown to have DNA encoding the P1.7b,4 PorA type. Therefore 22.6% (24/106) were defined as group B with an alternative PorA type. In 55 instances both an isolate and DNA from a patient specimen were received and characterised. In all cases the PCR result corresponded with that obtained for the culture submitted. This included seven situations where a throat isolate was received in addition to DNA from a sterile site specimen.

2.6.3. Overall Burden of Disease By combining the serotyping results for isolates (n=242) and the genotyping results on DNA from PCR positive specimens (n=120) it was shown that a total of 259 (177 + 82) cases out of 362 (71.5%) were caused by meningococci with the P1.7b,4 PorA protein [Appendix: Table 28]. This is marginally less than the proportion in 2002 when subtype P1.7b,4 was responsible for 77.3% (297/384) of cases. The overall estimate of the number of cases in 2003 attributable to group B meningococci with the P1.7b,4 PorA protein would be 387 (71.5% of 541 cases) which would give a rate of disease of 10.4 per 100 000 population. This estimate is based on the assumption that all confirmed and probable


cases that were reported in 2003 were actual cases of meningococcal disease and that the organism distribution among probable cases was similar to that among confirmed cases. Group C accounted for 31 cases confirmed by positive culture and 14 others confirmed by PCR, giving a total of 45 cases (12.4%). Applying the same assumption for group C disease it is estimated that 67 cases (12.4% of 541 cases) may have been caused by group C meningococci.

2.6.4. Meningococci associated with fatal cases Twelve of the 13 cases of meningococcal disease who died were confirmed, nine by isolation of N. meningitidis from a sterile site prior to, or at death, and three by PCR of a sterile site specimen [Appendix: Table 29]. Seven of the cases had group B disease and of these five had the epidemic type. The other two had distinct PorA types. The remaining five fatal cases were associated with group C. Of these, three were PorA type P1.5,10. 2.7. Antimicrobial susceptibility The antimicrobial susceptibility of 243 viable meningococcal isolates received at ESR from cases of invasive disease in 2003 was tested. This number includes one throat isolate from a case that had the same organism confirmed by PCR. All isolates were susceptible to penicillin, ceftriaxone and ciprofloxacin. One isolate (0.4%) was rifampicin resistant. 7.8% (19/243) of isolates had reduced penicillin susceptibility, with MICs of 0.12-0.5 mg/L (Table 6).

Table 6. MIC range and MIC90 of isolates, 2003

Antimicrobial MIC range (mg/L)

MIC90

(mg/L) Penicillin 0.016-0.5 0.06 Ceftriaxone 0.002-0.004 0.002 Rifampicin 0.002-32 0.03 Ciprofloxacin 0.002-0.008 0.004

The proportion of isolates with reduced penicillin susceptibility has increased over the last 11 years, varying from a low of 0% in 1992 to a high of 18.5% in 1999 (Figure 20). No resistance to ceftriaxone or ciprofloxacin has been confirmed among meningococci isolated from cases of invasive disease in New Zealand. Four rifampicin-resistant isolates have been confirmed: one serogroup B (B:4:P1.4) isolate in 2003, one serogroup C (C:2b:P1.2) isolate in 1997, one serogroup B (B:15:P1.7,16) isolate in 1992, and one serogroup A isolate in 1986.


Figure 20: Reduced susceptibility to penicillin among meningococci from invasive disease, 1992-2003

0.0

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1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

% re

duce

d su

scep

tibili

ty

3. Clinical outcome

3.1. Case-fatality Figure 21 shows the case-fatality rates for meningococcal disease in the years 1991-2003. Meningococcal disease resulted in 13 deaths in 2003, a case-fatality rate of 2.4%, the lowest to date throughout the course of the epidemic. The total number of fatalities since the epidemic began in 1991 is 216, giving an average case-fatality rate for the epidemic of 4.1%. This total is an excess of 189 deaths over the number that would have occurred had the pre-epidemic incidence rate of 1989-90 continued during this 13-year period. The average case fatality rate for the last five years (1999-2003) is 3.6%. [Appendix: Tables 29 & 30.] The case fatality rate for the last five years is greatest for the 40+ age group (10.9%, 22 deaths) and least for the 5-9 year age group (0.3%, 1 death). By ethnicity, the case fatality rate (1999-2003) is greatest for Europeans (4.3%) followed by Maori (3.1%) and Pacific Peoples (2.5%). The five-year case fatality rate for serogroup C is 10.4%, compared to 3.8% for serogroup B.


Figure 21: Meningococcal disease case-fatality rates, 1991-2003

0

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4

5

6

1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Year

Cas

e-fa

talit

y ra

te (%

)

Introduction of campaign to increase the use of pre-hospital

antibiotic treatment

4. Case management

4.1. Hospitalisation Information on hospitalisation was recorded for all 541 meningococcal disease cases reported in 2003. A total of 526 (97.2%) cases were recorded as having been hospitalised. Of the 15 cases which were not hospitalised, four died before being admitted to hospital, two cases were seen in accident and emergency departments but not hospitalised, one had conjunctivitis (plus one had a positive result from an eye swab), three cases saw a doctor but were not hospitalised, one case was seen by a District Nurse and a further three cases neither saw a doctor nor were hospitalised. Thirteen of the 15 non-hospitalised cases were confirmed, eight by isolation and five by PCR. One of the two probable cases had a positive throat isolate.

4.2. Pre-hospital visit to doctor and antibiotic treatment The Ministry of Health has advocated administration of pre-hospital antibiotics prior to admission to hospital.28 Table 7 shows meningococcal case outcome in relation to pre-hospital visit to a doctor and antibiotic treatment in 2003. Data on pre-hospital management (whether a case visited a doctor prior to hospital admission and whether they received pre-hospital antibiotic treatment) was recorded for 534 (98.7%) of the 541 cases reported in 2003, including all of the 13 fatal cases. Cases recorded as having received antibiotics prior to hospitalisation but not seen by a doctor were assigned to the ‘not recorded’ category as it was indeterminable which of the two criteria was valid. These data showed that 24.2% of cases (129/534) were reported as having received antibiotics prior to admission to hospital in 2003. This is slightly higher than the 21.2% (112/529) of cases who received such treatment in 2002. The case-fatality rate among those seen by a doctor and given The Epidemiology of Meningococcal Disease 27 May 2004 in New Zealand in 2003

antibiotics was 1.6%, compared with 2.6% who were seen by a doctor but not given antibiotics. A case-fatality rate of 2.9% occurred in those cases not seen by a doctor and not given antibiotics (Table 7). This is lower than the case fatality rate of 3.8% among cases in 2002 who were not seen by a doctor and not given antibiotics. Table 7. Meningococcal disease outcome in relationship to being seen by a doctor and receiving pre-hospital antibiotic treatment, 2003

Seen by doctor prior to admission

IV/IM antibiotics prior to hospital

admission

Died

Total

Case-fatality

rate (%) Yes Yes 2 129 1.6 Yes No 6 233 2.6 Yes Not recorded 0 1 0.0 Yes Total 8 363 2.2 No No 5 172 2.9 Not recorded No or not recorded 0 6 0.0

Total 13 541 2.4 Table 8 shows meningococcal disease outcome in relation to pre-hospital antibiotic treatment for the years 1999-2003. Table 8. Meningococcal disease outcome in relationship to being seen by a doctor and receiving pre-hospital antibiotic treatment, 1999-2003

Case-fatality rate (%) Seen by doctor prior to admission

IV/IM antibiotics prior

to hospital admission

1999 (n=504)

2000 (n=480)

2001 (n=650)

2002 (n=557)

2003 (n=541)

Total (1999-2003)

Yes Yes 1.5 2.0 2.2 1.8 1.6 1.8 Yes No 1.9 3.7 2.6 3.5 2.6 2.8 Yes Not recorded 0.0 3.1 5.6 0.0 0.0 2.3 Yes Total 1.6 3.1 2.6 2.9 2.2 2.5 No No or not

recorded 13.2 4.3 7.5 3.8 2.9 5.8

Not recorded

No or not recorded

12.5 4.4 2.7 4.5 0.0 5.6

Total 4.4 3.5 4.0 3.2 2.4 3.5 Note that conclusions based on the data contained within Tables 7 and 8 must be qualified by the potential confounding of other determinants of disease outcome, such as disease severity at the time of presentation.


4.3. Pre-hospital antibiotic treatment by age group Table 9 shows the age group distribution of cases of meningococcal disease given pre-hospital antibiotics in 2003. The proportion of cases reported as receiving pre-hospital antibiotics was highest for the 10-14 and 20-29 year age groups and lowest for the 30-39 and 40+ year age groups. Table 9. Pre-hospital antibiotic treatment of meningococcal disease cases by age group, 2003 Age group No. Pre-hospital antibiotic treatment (years) of cases Yes No Unknown % treated1 <1 68 12 55 1 17.9 1-4 129 36 90 3 28.6 5-9 69 18 51 0 26.1 10-14 46 18 28 0 39.1 15-19 85 17 68 0 20.0 20-29 63 20 42 1 32.3 30-39 25 1 23 1 4.2 40+ 56 8 48 0 14.3 Total 541 130 405 6 24.3 1 Percentage (%) of cases for whom this information was available

5. Risk factors

5.1. Contact with case In 2003, ‘contact with a case’ was unknown for only five cases. Of the 536 cases for whom these details were known through case reports or laboratory testing, 15 (2.8%) were recorded as contacts, i.e. as possible associated cases. Of the 15 cases that were considered contacts of cases, four were recorded as having been offered chemoprophylaxis, with three recorded as having received chemoprophylaxis. Information was available on 14 suspected index cases (Table 10). In one instance an index and associated case were recorded twice where each was defined as the index and the associated case of the other. Details on these cases have only been included once in the table (with the earliest case as the index case). Furthermore one associated case had two index cases recorded. Details on both are summarised in the table. Cases occurring on the same day, or within one day, of the index case are classified as co-primary associated cases while cases occurring greater than one day apart are classified as potentially associated cases. In 2003, four cases were classified as co-primary associated cases, and eight as potentially associated cases. A further case had two index cases, for one there was a delay of one day between onset in the index case and onset in the associated case, for the other index the case the delay was two days. [Appendix: Tables 31 & 32.]


Table 10. Relationship between associated cases of meningococcal disease and suspected index case, 2003

Associated case

Index case

Delay between

onset

No.

Sex/ Age

Basis/

Organism

Prophyla

xis Taken

Sex/ Age

Basis/

Organism

Nature of

contact

in index case to onset in

associated case

(days) 1 M/3 Probable Unknown M/1 Probable Brother 0 2 F/3 Probable Unknown F/2 Probable Unknown 1 3 M/3 Probable Unknown M/9 Probable Sibling 1 4

M/15 Isolate

B:4:P1.4 Yes M/15 PCR

B:P1.7,4 Household 1 5

F/14 Probable Unknown F/8mths & M/4mths

Probable & Probable Cousin 2 & 1

6 M/18

Isolate C:2a:P1.5 Unknown M/18

PCR C Institutional 2

7 M14 Probable Unknown M/3 Probable Nephew 3 8

M/12 PCR Unknown M/1 PCR

B Unknown 3 9

M/3 Isolate

B:4:P1.4 Unknown M/3 Probable Household 5 10

F/18 Isolate

C:2a:P1.5 Yes M/2 Isolate

C:2a:P1.5 Preschool Teacher 16

11 F/2 Probable No F/1

Isolate B:4:P1.4 Sibling 19

12 F/32 Throat Yes F/8mths

Isolate B:4:P1.4 Unknown 20

13 F/3

Isolate B:4:P1.4 Unknown F/50

Isolate B:4:P1.4 Unknown 20


Discussion Meningococcal disease remains the most important notifiable disease in New Zealand. Since 1990 the number of notified cases of disease increased from 53 (a rate of 1.5 per 100 000) to a peak of 613 in 1997 (16.9 per 100 000) and a second peak of 650 in 2001 (17.4 per 100 000). In 2002 and 2003 case numbers were 557 and 541 with rates of 14.9 and 14.5 per 100 000 respectively. A suggestion that New Zealand’s epidemic had finally peaked in 2001 is not borne out by the 2002 and 2003 data. The experience in Norway suggests that without an effective intervention, any natural decline in disease numbers is likely to be slow27. The delivery of an outer membrane vaccine targeting the epidemic strain B:4:P1.19,15 in Cuba in the late 1980s was associated with a steep decline in case numbers. Rates of disease in under six year olds fell from the peak of 42.5/100 000 in Havana City in 1988 to 15/100 000 in 198929. The trialling of a vaccine, MeNZB, targeting New Zealand’s epidemic strain is based on an expectation that if the vaccine is licensed to be used in the wider community, case numbers should decline at a faster rate than without intervention and that disease rates should decrease correspondingly28. Summated notification data for meningococcal disease is based on both confirmed and probable cases according to a standard definition used for disease surveillance in New Zealand23. Confirmation of disease requires evidence of meningococci in patient specimens. Early in the 1990s meningococcal disease confirmation was achieved primarily by isolation of a meningococcus from a normally sterile site, usually CSF or blood. The advent of DNA technology allowed identification of meningococcal DNA in patient specimens. Not only does PCR provide confirmation of disease but also allows genotyping of meningococci causing disease. DNA testing for meningococcal disease was introduced at ESR in 1997 and has been increasingly used since then. In 2003, 36.6% of the 388 confirmed cases were confirmed only by PCR testing. The value of PCR testing to enable confirmation of disease has been demonstrated in relation to the use of antibiotics given to cases prior to admission to hospital. For example, in 2003 only 24.6% (32/130) of those given IV/IM antibiotics prior to admission to hospital grew a meningococcus from blood and/or CSF whereas 51.9% (210/405) who had not received antibiotics prior to admission to hospital had a meningococcus recovered. The use of PCR will continue to be important during the mass vaccination campaign by enabling identification and typing of meningococci in cases from whom a culture is not available. Vaccine effectiveness evaluation will be impaired without the assistance of PCR genotyping to define the organism type. Once again the disparity in laboratory testing undertaken on suspected cases of meningococcal disease was highlighted in 2003. Northland, Waitemata, Auckland and Counties-Manukau DHBs consistently have had a lower proportion of confirmed cases of disease. In 2003, less than 60% of cases from Auckland, Northland, and Waitemata DHBs were confirmed. A correlation between unconfirmed cases and age group has been identified since 1995, with cases <10 years of age regardless of ethnicity being confirmed less often. Overall, confirmation of disease in 2003 was highest for European (80.0%) and lowest for Pacific Peoples (52.2%). Analysis of data by utilisation of laboratory tests has highlighted that for many of the culture-negative cases PCR tests are not undertaken. It will be very important during the vaccine programme that greater use is made of PCR as a test both for confirming disease and for defining the strain type. Four of the major hospitals (Auckland, Waikato, Wellington and Christchurch) offer PCR testing using real-time PCR, a very sensitive testing process. In its capacity as a national public health laboratory, ESR provides DNA testing to enable organism identification.


The highest age-specific rates of disease occur in infants. For 2003, the age-specific rate in infants <1 year was 124.4 per 100 000 population and in those aged 1-4 years 59.7 per 100 000 population. The association between rates of disease and deprivation index were most marked for under 5 year olds across the country. A noticeable decline in percentages of cases aged less than five years has occurred since 1999; from 56.7% in 1999 to 36.4% in 2003. This implies a shift upwards in the age distribution of cases as shown in the teenage population. Examining those <10 years of age, rates for both Pacific peoples and for Maori are significantly higher (Pacific peoples chi-square=271.58, p<0.0001 and Maori chi-square = 114.54, p<0.0001) when compared with Europeans <10 years of age. In 2001 and 2002 the median age for Maori cases was 2.6 and 2.9 respectively but in 2003 this increased to 5.2. As in other industrialised countries groups B and C have caused most meningococcal disease in New Zealand. Groups A, W135 and Y have been rarely involved. An increase in group B causing disease in 1991 heralded the beginning of the epidemic.9 Since 1995, the proportion of group B isolates expressing the PorA protein type P1.7b,4 has been around 90% annually. The proportion was lower for those identified by PCR sequencing in 2003 at 77.4% but this result is possibly skewed because a number of PCR positive specimens were unable to be PorA genotyped. The proportion of those confirmed by culture was consistent with previous years at 88.9%. Not all group B with the PorA type P1.7b,4 have the PorB type (serotype) 4. Alternatives include types 14, 1, 15 and a type for which monoclonal antibodies are not available, defined as 19,D,7,14a30. These strains have the same clonal derivation as those typing as B:4:P1.7b,4 and are included as an epidemic type30. The proportion of group C meningococci causing disease has varied from year to year. In 1991, 27.3% (15/55) of culture-confirmed cases were caused by group C, but by 2000 this proportion had dropped to only 3.9% (10/256). A resurgence of group C disease over the last three years has largely been confined to the South Island. Group C was responsible for a cluster of cases reported in Otago during 2002. This cluster was caused by a new group C strain with the PorA type P1.10,8. Previously most C disease in New Zealand was caused by isolates with the PorA type P1.5,2. Over the last 10 years strategies to assist control of New Zealand’s epidemic have been put in place. In 1995, the Ministry of Health held a workshop to assist the development of a national prevention and control plan for meningococcal disease31. Following on from that General Practitioners were advised to administer antibiotics to suspected cases of meningococcal disease prior to admission to hospital. This policy has undoubtedly saved lives but has little impact on the continuing high rates of disease. Following a meeting held by the World Health Organisation in 1998 a strategy to control New Zealand’s epidemic by use of a vaccine specifically targeting the epidemic strain was formulated. The Ministry of Health contracted Chiron Corporation in collaboration with the Norwegian Institute of Public Health to manufacture such a vaccine for use in New Zealand. Successful clinical trials so far undertaken to demonstrate an immune response to the vaccine and no serious adverse events has led to an application to Medsafe under Section 23 of the Medicines Act 1981 to immunise children and young people under the age of 20 years in a staged programme prioritised by disease risk32.


If provisional licensure is granted, the rollout of MeNZB is planned to commence from June 2004, subject to licensure conditions. The programme will commence in Counties Manukau DHB and a geographically defined “eastern corridor” of Auckland DHB and then be progressively rolled out nationwide. The Meningococcal Vaccine Strategy (MVS) also incorporates extensive post-licensure safety monitoring of the vaccine. This will rely heavily on being able to track

immunisations through the National Immunisation Register which is nearing completion. Rollout of the programme will occur knowing that MeNZB is immunogenic but without efficacy data. A number of observational studies are planned post-licensure to assess effectiveness of the vaccine. Throughout the rollout, evaluation of the programme will also occur. Vaccine coverage assessment alongside qualitative methodologies will be a key element of this evaluation, examining in particular, delivery of vaccine to those at highest risk, namely Maori and Pacific children aged less than five years. Effective surveillance of the organism and health outcomes will be a key element of these evaluations.


Appendix Table 11. Numbers and rates for cases of meningococcal disease by District Health Board, 1999-2003

1999 2000 2001 2002 2003 District Health Board

No. Rate1 No. Rate1 No. Rate1 No.2 Rate1 No. Rate1

Northland 38 27.1 25 17.8 37 26.4 29 20.7 37 26.4 Waitemata 48 11.2 39 9.1 37 8.6 35 8.1 55 12.8 Auckland 69 18.8 77 20.9 79 21.5 45 12.2 68 18.5 Counties Manukau 110 29.3 119 31.7 126 33.6 87 23.2 107 28.5 Waikato 34 10.7 46 14.5 72 22.7 38 12.0 42 13.2 Lakes 24 25.0 12 12.5 39 40.6 53 55.2 26 27.1 Bay of Plenty 29 16.3 25 14.0 32 18.0 51 28.6 43 24.1 Tairawhiti 6 13.7 12 27.3 11 25.0 6 13.7 4 9.1 Taranaki 7 6.8 5 4.9 10 9.7 10 9.7 6 5.8 Hawke's Bay 20 13.9 18 12.5 29 20.2 31 21.6 18 12.5 Whanganui 5 7.9 10 15.7 7 11.0 6 9.4 18 28.3 MidCentral 1 0.6 9 5.8 20 12.9 10 6.5 9 5.8 Hutt 16 12.1 9 6.8 16 12.1 12 9.1 13 9.9 Capital and Coast 14 5.7 18 7.3 24 9.8 28 11.4 21 8.5 Wairarapa 5 13.1 6 15.7 11 28.8 3 7.9 2 5.2 Nelson Marlborough 1 0.8 5 4.1 12 9.8 3 2.4 1 0.8 West Coast 0 0.0 0 0.0 3 9.9 8 26.4 1 3.3 Canterbury 33 7.7 20 4.7 18 4.2 33 7.7 33 7.7 South Canterbury 2 3.8 3 5.7 3 5.7 6 11.4 3 5.7 Otago 23 13.5 17 10.0 54 31.6 49 28.7 23 13.5 Southland 19 18.4 5 4.8 10 9.7 14 13.5 11 10.6 New Zealand total

504 13.5 480 12.8 650 17.4 557 14.9 541 14.5

1 Rate per 100 000 population based on 2001 census data. Hence NZ total rate for 1999 and 2000 differ from those previously published where 1996 census data was used.

2 Number of cases for Waikato, West Coast, Taranaki and MidCentral differ by 1 from those published in 2002 Annual Meningococcal Report.


Table 12. Geographic distribution by District Health Board of confirmed cases of meningococcal disease and proportion of confirmed to total cases, 1999-2003

1999 2000 2001 2002 2003 District Health Board

No. Rate1 %2 No. Rate1 %2 No. Rate1 %2 No.3 Rate1 %2 No. Rate1 %2

Northland 28 20.0 73.7 22 15.7 88.0 27 19.3 73.0 22 15.7 75.9 20 14.3 54.1 Waitemata 26 6.0 54.2 22 5.1 56.4 18 4.2 48.6 19 4.4 54.3 31 7.2 56.4 Auckland 39 10.6 56.5 56 15.2 72.7 45 12.2 57.0 20 5.4 44.4 34 9.2 50.0 Counties Manukau 69 18.4 62.7 62 16.5 52.1 77 20.5 61.1 42 11.2 48.3 65 17.3 60.7 Waikato 23 7.2 67.6 35 11.0 76.1 62 19.5 86.1 34 10.7 89.5 41 12.9 97.6 Lakes 18 18.8 75.0 10 10.4 83.3 39 40.6 100 51 53.1 96.2 22 22.9 84.6 Bay of Plenty 20 11.2 69.0 20 11.2 80.0 27 15.2 84.4 48 26.9 94.1 36 20.2 83.7 Tairawhiti 5 11.4 83.3 12 27.3 100 8 18.2 72.7 5 11.4 83.3 4 9.1 100 Taranaki 7 6.8 100 5 4.9 100 9 8.7 90.0 9 8.7 90.0 4 3.9 66.7 Hawke's Bay 11 7.7 55.0 14 9.8 77.8 19 13.2 65.5 18 12.5 58.1 12 8.4 66.7 Whanganui 5 7.9 100 8 12.6 80.0 7 11.0 100 4 6.3 66.7 17 26.7 94.4 MidCentral 1 0.6 100 9 5.8 100 16 10.3 80.0 7 4.5 70.0 7 4.5 77.8 Hutt 14 10.6 87.5 9 6.8 100 12 9.1 75.0 10 7.6 83.3 12 9.1 92.3 Capital and Coast 11 4.5 78.6 14 5.7 77.8 21 8.5 87.5 26 10.6 92.9 20 8.1 95.2 Wairarapa 4 10.5 80.0 5 13.1 83.3 11 28.8 100 3 7.9 100 2 5.2 100 Nelson Marlborough 1 0.8 100 5 4.1 100 10 8.2 83.3 3 2.4 100 0 0.0 0.0 West Coast 0 0.0 N/A 0 0.0 N/A 2 6.6 66.7 6 19.8 75.0 0 0.0 0.0 Canterbury 24 5.6 72.7 18 4.2 90.0 16 3.7 88.9 26 6.1 78.8 29 6.8 87.9 South Canterbury 2 3.8 100 2 3.8 66.7 3 5.7 100 5 9.5 83.3 3 5.7 100 Otago 14 8.2 60.9 16 9.4 94.1 50 29.3 92.6 45 26.4 91.8 19 11.1 82.6 Southland 11 10.6 57.9 4 3.9 80.0 10 9.7 100 10 9.7 71.4 10 9.7 90.9 New Zealand total

333 8.9 66.1 348 9.3 72.5 489 13.1 75.2 413 11.1 74.1 388 10.4 71.7

1 Rate per 100 000 population based on 2001 census data. Hence NZ total rate for 1999 and 2000 differ from those previously published where 1996 census data was used.

2 Proportion (%) of total cases who were confirmed. 3 Number of cases for Waikato, West Coast, Taranaki and MidCentral differ by 1 from those published in 2002 Annual Meningococcal Report.


Table 13. Age distribution of meningococcal disease cases, 1999-2003

Age group

1999 2000 2001 2002 2003

(years) No. Rate No. Rate 1 No. Rate 2 No. Rate 2 No. Rate 2

99 181.0 91 166.3 112 205.0 84 153.7 68 124.4

1-4 187 148 65.8 176 81.4 155 71.7 129 59.7

5-9 49 17.0 59 75 26.2 59 20.6 69 24.1

10-14 33 12.5 48 18.2 70

1

<1 83.2

20.5 24.1 54 18.6 46 15.8

15-19 55 20.9 49 35.8 82 30.9 85 32.0

20-29 43 7.9 37 6.8 57 11.7 53 10.9 12.9

30-39 15 2.6 15 2.6 25 4.3 21 3.6 25 4.3

40+ 23 33 2.4 40 2.6 49 3.1 56 3.6

Total 504 13.9 480 13.3 650 17.4 14.9 541 14.5

286 102.3 239 85.5 288 106.3 239 88.3 197 72.7

≥5 218 6.5 241 7.2 10.4 318 9.2 344 9.9 1 Rate per 100 000 population based on 1996 census data.2 Rate per 100 000 population based on 2001 census data.

Table 14. Age group distribution for confirmed cases of meningococcal disease and proportion of confirmed to total cases, 1999-2003

1999 2001 2002 2003 Age group (years)

No. Rate 1 % 3 No. Rate 1 % 3 No. 2 % 3 No. Rate2 % 3 No. Rate2 % 3

<1 61 61.6 60 109.7 65.9 75 137.2 67.0 63 115.3 75.0 45 82.3 66.2 1-4 115 61.5 110 48.9 74.3 127 58.7 72.2 99 45.8 63.9 76 35.2 58.9 5-9 33 67.3 33 11.5 55.9 48 16.8 64.0 37 12.9

18.6 95 63

1.6 557

<5 362

2000 Rate

111.5 51.1 11.5 62.7 45 15.7 65.2

10-14 24 9.1 72.7 33 12.5 68.8 54 18.6 77.1 36 12.4 66.7 32 11.0 69.6 15-19 39 14.8 70.9 40 15.2 81.6 78 29.4 82.1 71 26.8 86.6 74 27.9 87.1 20-29 32 5.9 74.4 30 5.5 81.1 47 9.7 82.5 44 9.0 83.0 53 10.9 84.1 30-39 11 1.9 73.3 14 2.4 93.3 23 4.0 92.0 19 3.3 90.5 17 2.9 68.0 40+ 18 1.3 78.3 28 2.0 84.8 37 2.4 92.5 44 2.8 89.8 46 2.9 82.1 Total 333 9.2 66.1 348 9.6 72.5 489 13.1 75.2 413 11.1 74.1 388 10.4 71.7 <5 176 63.0 61.5 170 60.8 71.1 202 74.6 70.1 162 59.8 67.8 121 44.7 61.4 ≥5 157 4.7 72.0 178 5.3 73.9 287 8.3 79.3 251 7.2 78.9 267 7.7 77.6

1 Rate per 100 000 population based on 1996 census data. 2 Rate per 100 000 population based on 2001 census data. 3 Proportion (%) of cases who were confirmed.


Table 15. Meningococcal disease cases, less than five year olds versus those age five years and over, 1990-2003

Age group Year <5 years >5 years Total % <5 years1990 27 26 53 50.9 1991 34 44 78 43.6 1992 62 93 155 40.0 1993 98 104 202 48.5 1994 96 112 208 46.2 1995 180 214 394 45.7 1996 242 231 473 51.2 1997 334 279 613 54.5 1998 217 223 440 49.3 1999 286 218 504 56.7 2000 239 241 480 49.8 2001 288 362 650 44.3 2002 239 318 557 42.9 2003 197 344 541 36.4 Table 16. Age distribution by months for total and confirmed cases of meningococcal disease aged 0-24 months, 2003 and 1999-2003

2003 1999-2003 Total cases Confirmed cases Total cases Confirmed cases Age (months)

No. Cum %1 (n=541)

No.

Cum %1 (n=388)

No.

Cum %1 (n=2732)

No.

Cum %1 (n=1971)

<1 1 0.2 1 0.3 15 0.5 12 0.6 1 2 0.6 1 0.5 20 1.3 15 1.4 2 7 1.8 6 2.1 39 2.7 27 2.7 3 5 2.8 5 3.4 41 4.2 28 4.2 4 10 4.6 6 4.9 64 6.6 42 6.3 5 6 5.7 5 6.2 43 8.1 36 8.1 6 5 6.7 4 7.2 38 9.5 29 9.6 7 7 7.9 4 8.2 39 10.9 23 10.8 8 2 8.3 1 8.5 35 12.2 21 11.8 9 9 10.0 2 9.0 40 13.7 15 12.6

10 6 11.1 4 10.1 36 15.0 27 14.0 11 8 12.6 6 11.6 44 16.6 29 15.4 12 6 13.7 4 12.6 36 17.9 24 16.6 13 3 14.2 3 13.4 35 19.2 25 17.9 14 6 15.3 4 14.4 24 20.1 19 18.9 15 3 15.9 0 14.4 20 20.8 10 19.4 16 5 16.8 4 15.5 27 21.8 20 20.4 17 8 18.3 4 16.5 32 23.0 17 21.3 18 2 18.7 1 16.8 24 23.9 20 22.3 19 6 19.8 4 17.8 19 24.6 11 22.8 20 2 20.1 2 18.3 24 25.4 17 23.7 21 2 20.5 2 18.8 22 26.2 15 24.5 22 3 21.1 2 19.3 28 27.3 17 25.3 23 0 21.1 0 19.3 10 27.6 5 25.6 24 0 21.1 0 19.3 13 28.1 13 26.2

Total 114 - 75 - 768 - 517 - 1 Cumulative percentage of cases in all age groups. The Epidemiology of Meningococcal Disease 37 May 2004 in New Zealand in 2003

Table 17. Numbers and rates for cases of meningococcal disease by age group and District Health Board, 2003

0-4 years 5-19 years 20+ years District Health Board

No. Rate1 No. Rate1 No. Rate1

Northland 17 162.7 17 50.1 3 3.1 Waitemata 17 54.5 16 16.5 22 7.3 Auckland 27 107.1 25 34.6 16 5.9 Counties Manukau

59 177.8 35 36.6 13 5.3

Waikato 15 61.6 19 24.8 8 3.7 Lakes 7 88.8 13 56.1 6 9.2 Bay of Plenty 8 60.7 17 41.4 18 14.5 Tairawhiti 0 0.0 1 8.7 3 10.5 Taranaki 3 41.4 2 8.2 1 1.4 Hawke's Bay 12 110.8 4 11.8 2 2.0 Whanganui 7 148.2 7 46.5 4 9.1 MidCentral 7 63.8 2 5.6 0 0.0 Hutt 4 39.2 4 13.2 5 5.5 Capital and Coast 3 17.4 5 10.0 13 7.3 Wairarapa 1 37.3 1 11.6 0 0.0 Nelson Marlborough

0 0.0 0 0.0 1 1.1

West Coast 1 51.5 0 0.0 0 0.0 Canterbury 4 14.6 12 13.5 17 5.5 South Canterbury 2 61.3 1 9.0 0 0.0 Otago 2 20.1 14 37.5 7 5.7 Southland 1 14.1 5 21.9 5 6.8 New Zealand total

197 72.7 200 23.7 144 5.5

1 Rate per 100 000 population based on 2001 census data. Table 18. Numbers and age-standardised incidence rates by ethnicity for cases of meningococcal disease, 1999-2003 1999 2000 2001 2002 2003 Ethnicity No. Rate1 No. Rate1 No. Rate2 No. Rate2 No. Rate2

European 207 9.1 177 7.7 264 11.5 280 12.1 245 10.4

Maori3 183 22.1 172 21.2 211 25.7 160 20.5 171 22.7

Pacific4 100 36.8 111 44.4 155 53.1 90 28.9 113 39.2

Other 13 6.8 16 7.9 13 4.9 19 6.8 12 4.3

Unknown 1 - 4 - 7 - 8 - 0 -

Total 504 13.9 480 13.3 650 17.4 557 14.9 541 14.5 1 Rate per 100 000 direct standardised to age distribution of the total NZ population (based on 1996 census data). 2 Rate per 100 000 direct standardised to age distribution of the total NZ population (based on 2001 census data). 3 Rate is calculated using mixed Maori ethnicity. 4 Rate is calculated using mixed Pacific people ethnicity (excluding Maori).


Table 19. Ethnicity distribution of confirmed cases of meningococcal disease and proportion of confirmed to total cases, 1999-2003

1999 2000 2001 2002 2003 Ethnicity No. Rate1 %3 No. Rate1 %3 No. Rate2 %3 No. Rate2 %3 No. Rate2 %3

European 133 5.8 64.3 138 5.9 78.0 221 9.5 83.7 227 9.7 81.1 196 8.3 80.0

Maori4 126 15.3 68.9 126 15.3 73.3 160 19.5 75.8 125 16.5 78.1 123 16.6 71.9

Pacific5 63 23.0 63.0 70 29.5 63.1 93 33.4 60.0 41 13.3 45.6 59 21.3 52.2

Other 11 5.7 84.6 10 4.6 62.5 8 3.1 61.5 13 4.4 68.4 10 3.8 83.3

Unknown6 0 - 0.0 4 - 100 7 - 100 7 - 87.5 0 - N/A

Total 333 9.2 66.1 348 9.6 72.5 489 13.1 75.2 413 11.1 74.1 388 10.4 71.7 1 Rate per 100 000 standardised to age distribution of the total NZ population (based on 1996 census data). 2 Rate per 100 000 standardised to age distribution of the total NZ population (based on 2001 census data). 3 Proportion (%) of total cases who were confirmed. 4 Rate is calculated using mixed Maori ethnicity. 5 Rate is calculated using mixed Pacific ethnicity (excluding Maori). 6 No rate can be calculated. Table 20. Numbers and crude incidence rates for cases of meningococcal disease by age group and ethnicity, 2003

Age group European Maori Pacific Other Unknown Total (years) No. Rate1 No. Rate1 No. Rate1 No. Rate1 No. No. Rate1

<1 13 43.7 28 200.1 26 504.2 1 26.9 0 68 124.4 1-4 29 23.8 54 100.9 45 234.7 1 7.1 0 129 59.7 5-9 18 10.7 35 52.9 15 63.5 1 5.4 0 69 24.1 10-14 16 9.0 21 33.4 9 41.5 0 0.0 0 46 15.8 15-19 67 41.7 9 18.2 5 27.6 4 14.3 0 85 32.0 20-29 46 15.1 9 10.9 5 14.8 3 6.9 0 63 12.9 30-39 19 4.8 4 5.2 2 6.3 0 0.0 0 25 4.3 40+ 37 3.0 11 9.1 6 12.8 2 2.7 0 56 3.6 Total 245 9.4 171 32.5 113 56.4 12 4.8 0 541 14.5 1 Crude rate per 100 000 population based on 2001 census data.


Table 21. Age group and ethnicity distribution for confirmed cases of meningococcal disease by age group and ethnicity, 2003

Age group European Maori Pacific Other Unknown Total (years) No. Rate1 No. Rate1 No. Rate1 No. Rate1 No. No. Rate1

<1 8 26.9 22 157.2 14 271.5 1 26.9 0 45 82.3 1-4 19 15.6 36 67.2 20 104.3 1 7.1 0 76 35.2 5-9 13 7.7 24 36.3 7 29.6 1 5.4 0 45 15.7 10-14 12 6.8 16 25.4 4 18.5 0 0.0 0 32 11.0 15-19 60 37.4 8 16.1 4 22.1 2 7.1 0 74 27.9 20-29 40 13.1 6 7.3 4 11.8 3 6.9 0 53 10.9 30-39 13 3.3 2 2.6 2 6.3 0 0.0 0 17 2.9 40+ 31 2.5 9 7.5 4 8.5 2 2.7 0 46 2.9 Total2 196 7.5 123 23.4 59 29.5 10 4.0 0 388 10.4 1 Crude rate per 100 000 population based on 2001 census data. Table 22. Numbers and rates for cases of meningococcal disease by ethnicity for District Health Board, 2003

European Maori Pacific people Other Unk District Health Board

No. Rate1 No. Rate1 No. Rate1 No. No.

Northland 11 13.0 26 63.8 0 0.0 0 0 Waitemata 34 11.3 11 27.7 9 33.8 1 0 Auckland 22 10.7 11 37.8 31 71.0 4 0 Counties Manukau 16 8.9 35 57.0 55 79.6 1 0

Waikato 17 7.6 23 35.8 1 15.0 1 0 Lakes 16 28.6 10 32.9 0 0.0 0 0 Bay of Plenty 28 22.7 14 32.8 0 0.0 1 0 Tairawhiti 2 9.3 1 5.2 1 153.6 0 0 Taranaki 3 3.6 3 20.6 0 0.0 0 0 Hawke's Bay 6 6.0 9 27.7 3 83.0 0 0 Whanganui 5 11.1 12 85.1 1 119.0 0 0 MidCentral 4 3.4 4 16.9 1 32.9 0 0 Hutt 6 6.5 3 15.3 3 34.3 1 0 Capital and Coast 13 7.5 2 8.2 5 26.8 1 0 Wairarapa 1 3.3 1 18.5 0 0.0 0 0 Nelson Marlborough 1 0.9 0 0.0 0 0.0 0 0

West Coast 1 3.8 0 0.0 0 0.0 0 0 Canterbury 26 7.2 4 13.9 3 41.4 0 0 South Canterbury 3 6.3 0 0.0 0 0.0 0 0 Otago 20 13.4 1 10.1 0 0.0 2 0 Southland 10 11.4 1 9.3 0 0.0 0 0 New Zealand total 245 9.4 171 32.5 113 56.4 12 0

1 Rate per 100 000 population based on 2001 census data.


Table 23. Gender distribution of meningococcal disease cases, 1999-2003 1999 2000 2001 2002 2003

Gender No. Rate1 No. Rate1 No. Rate2 No. Rate2 No. Rate2 Male 285 16.0 262 14.7 370 20.3 305 16.7 293 16.1 Female 219 11.9 218 11.8 277 14.5 247 12.9 244 12.7 Unknown - - - - 3 - 5 - 4 - Total 504 13.9 480 13.3 650 17.4 557 14.9 541 14.5 1 Rate per 100 000 population based on 1996 census data. 2 Rate per 100 000 population based on 2001 census data.

Table 24. Gender distribution of confirmed cases of meningococcal disease and proportion of confirmed to total cases, 1999-2003

1999 2000 2001 2002 2003 Gender No. Rate1 %3 No. Rate1 %3 No. Rate2 %3 No. Rate2 %3 No. Rate2 %3

Male 195 11.0 68.4 181 10.2 69.1 267 14.6 72.2 230 12.6 75.4 209 11.5 71.3 Female 138 7.5 63.0 167 9.1 76.6 221 11.5 79.8 180 9.4 72.9 176 9.2 72.1 Unknown - - - - - - 1 - 33.3 3 - 60.0 3 - 75.0 Total 333 9.2 66.1 348 9.6 72.5 489 13.1 75.2 413 11.1 74.1 388 10.4 71.7

1 Rate per 100 000 population based on 1996 census data. 2 Rate per 100 000 population based on 2001 census data. 3 Proportion (%) of cases who were confirmed. Table 25. Cases of meningococcal disease by District Health Board for PCR and other means of confirmation, 2003

2003 District Health Board

No. total cases

No. confirmed

cases

% total cases

confirmed

No. cases confirmed

by PCR

% of total cases

confirmed by PCR

No. cases confirmed by means other than

PCR

% of total cases

confirmed by means other than

PCR

No. probable

cases

Northland 37 20 54.1 4 10.8 16 43.2 17 Waitemata 55 31 56.4 10 18.2 21 38.2 24 Auckland 68 34 50.0 9 13.2 25 36.8 34 Counties Manukau 107 65 60.7 22 20.6 43 40.2 42 Waikato 42 41 97.6 15 35.7 26 61.9 1 Lakes 26 22 84.6 13 50.0 9 34.6 4 Bay of Plenty 43 36 83.7 21 48.8 15 34.9 7 Tairawhiti 4 4 100 2 50.0 2 50.0 0 Taranaki 6 4 66.7 1 16.7 3 50.0 2 Hawke's Bay 18 12 66.7 3 16.7 9 50.0 6 Whanganui 18 17 94.4 8 44.4 9 50.0 1 MidCentral 9 7 77.8 3 33.3 4 44.4 2 Hutt 13 12 92.3 6 46.2 6 46.2 1 Capital and Coast 21 20 95.2 5 23.8 15 71.4 1 Wairarapa 2 2 100 0 0.0 2 100 0 Nelson Marlborough 1 0 0.0 0 0.0 0 0.0 1 West Coast 1 0 0.0 0 0.0 0 0.0 1 Canterbury 33 29 87.9 12 36.4 17 51.5 4 South Canterbury 3 3 100 1 33.3 2 66.7 0 Otago 23 19 82.6 3 13.0 16 69.6 4 Southland 11 10 90.9 4 36.4 6 54.5 1 New Zealand total 541 388 71.7 142 26.2 246 45.5 153


Table 26. Cases of meningococcal disease by age group and District Health Board for PCR and other means of confirmation, 2003

<1 Year 1-4 Years 5-19 Years 20+ Years District Health Board

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

Northland 75.0 25.0 50.0 53.8 7.7 46.2 58.8 11.8 47.1 0.0 0.0 0.0 Waitemata 16.7 0.0 16.7 27.3 0.0 27.3 75.0 18.8 56.3 68.2 31.8 36.4 Auckland 33.3 0.0 33.3 33.3 5.6 27.8 56.0 16.0 40.0 68.8 25.0 43.8 Counties Manukau 54.5 9.1 45.5 56.8 21.6 35.1 60.0 20.0 40.0 84.6 38.5 46.2 Waikato 100 20.0 80.0 90.0 60.0 30.0 100 26.3 73.7 100 37.5 62.5 Lakes 100 40.0 60.0 100 0.0 100 76.9 46.2 30.8 83.3 83.3 0.0 Bay of Plenty 100 0.0 100 100 50.0 50.0 82.4 47.1 35.3 77.8 55.6 22.2 Tairawhiti - - - - - - 100 100 0.0 100 33.3 66.7 Taranaki - - - 33.3 0.0 33.3 100 50.0 50.0 100 0.0 100 Hawke's Bay 100 0.0 100 60.0 30.0 30.0 75.0 0.0 75.0 50.0 0.0 50.0 Whanganui 100 100 0.0 100 50.0 50.0 100 42.9 57.1 75.0 25.0 50.0 MidCentral 100 60.0 40.0 50.0 0.0 50.0 50.0 0.0 50.0 - - - Hutt 100 100 0.0 66.7 0.0 66.7 100 100 0.0 100 20.0 80.0 Capital and Coast 100 0.0 100 100 0.0 100 80.0 40.0 40.0 100 23.1 76.9 Wairarapa - - - 100 0.0 100 100 0.0 100 - - - Nelson Marlborough - - - - - - - - - 0.0 0.0 0.0 West Coast - - - 0.0 0.0 0.0 - - - - - - Canterbury 100 0.0 100 100 33.3 66.7 83.3 50.0 33.3 88.2 29.4 58.8 South Canterbury 100 0.0 100 - - - 100 100 0.0 - - - Otago 0.0 0.0 0.0 0.0 0.0 0.0 85.7 14.3 71.4 100 14.3 85.7 Southland 100 0.0 100 - - - 100 20.0 80.0 80.0 60.0 20.0 New Zealand total 66.2 16.2 50.0 58.9 20.2 38.8 75.5 28.0 47.5 80.6 34.0 46.5


Table 27. Cases of meningococcal disease by ethnicity and District Health Board for PCR and other means of confirmation, 2003

European Maori Pacific people Other Unknown District Health Board

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

% o

f tot

al c

ases

co

nfir

med

% o

f tot

al c

ases

co

nfir

med

by

PCR

%

of t

otal

cas

es

conf

irm

ed b

y m

eans

ot

her

than

PC

R

Northland 45.5 9.1 36.4 57.7 11.5 46.2 - - - - - - - - - Waitemata 58.8 20.6 38.2 45.5 0.0 45.5 55.6 33.3 22.2 100 0.0 100 - - - Auckland 72.7 22.7 50.0 45.5 9.1 36.4 32.3 9.7 22.6 75.0 0.0 75.0 - - - Counties Manukau 87.5 31.3 56.3 65.7 31.4 34.3 49.1 10.9 38.2 100 0.0 100 - - - Waikato 100 35.3 64.7 95.7 39.1 56.5 100 0.0 100 100 0.0 100 - - - Lakes 87.5 56.3 31.3 80.0 40.0 40.0 - - - - - - - - - Bay of Plenty 82.1 53.6 28.6 85.7 35.7 50.0 - - - 100 100 0.0 - - - Tairawhiti 100 50.0 50.0 100 100 0.0 100 0.0 100 - - - - - - Taranaki 100 33.3 66.7 33.3 0.0 33.3 - - - - - - - - - Hawke's Bay 50.0 0.0 50.0 66.7 33.3 33.3 100 0.0 100 - - - - - - Whanganui 100 20.0 80.0 91.7 58.3 33.3 100 0.0 100 - - - - - - MidCentral 50.0 0.0 50.0 100 75.0 25.0 100 0.0 100 - - - - - - Hutt 100 33.3 66.7 100 66.7 33.3 66.7 66.7 0.0 100 0.0 100 - - - Capital and Coast 100 30.8 69.2 50.0 50.0 0.0 100 0.0 100 100 0.0 100 - - - Wairarapa 100 0.0 100 100 0.0 100 - - - - - - - - - Nelson Marlborough 0.0 0.0 0.0 - - - - - - - - - - - - West Coast 0.0 0.0 0.0 - - - - - - - - - - - - Canterbury 84.6 34.6 50.0 100 25.0 75.0 100 66.7 33.3 - - - - - - South Canterbury 100 33.3 66.7 - - - - - - - - - - - - Otago 90.0 15.0 75.0 0.0 0.0 0.0 - - - 50.0 0.0 50.0 - - - Southland 90.0 40.0 50.0 100 0.0 100 - - - - - - - - - New Zealand total 80.0 30.2 49.8 71.9 29.8 42.1 52.2 14.2 38.1 83.3 8.3 75.0 - - -

Table 28. Distribution of meningococcal isolate and PCR results defined by serotyping or DNA sequence analysis, 2003

Group

PorA type

Number Percentage of

Group B Percentage of

total B P1.4 259 84.9 71.5 B Other PorA 46 15.1 12.7

Total B 305 100 84.3 C 45 12.4

W135 7 1.9 Y 5 1.4

TOTAL 362 100


Table 29. Case-fatality rates for meningococcal disease cases by age, gender, ethnicity, serogroup, clinical description and basis, 1999-2003

Features of Number of fatalities Case- case and infecting organism

1999

2000

2001

2002 2003

Total fatalities

99-03

Total cases 99-03

fatality rate (%)

<1 year 5 2 3 3 2 15 454 3.3 1-4 years 6 6 7 3 2 24 795 3.0 5-9 years 0 0 0 1 0 1 311 0.3 10-14 years 2 0 2 0 1 5 251 2.0 15-19 years 2 2 5 5 3 17 366 4.6 20-29 years 2 1 4 0 2 9 253 3.6 30-39 years 1 2 1 0 0 4 101 4.0 40+ years 5 4 4 6 3 22 201 10.9 Male 9 9 16 8 5 47 1515 3.1 Female 14 8 10 10 8 50 1205 4.1 European 12 11 12 10 5 50 1173 4.3 Maori 8 4 9 5 2 28 897 3.1 Pacific 3 2 4 2 3 14 569 2.5 Other 0 0 1 1 3 5 73 6.8 Unknown 0 0 0 0 0 0 20 0.0 Group B* 11 12 18 5 7 53 1387 3.8 Group C* 1 1 3 5 5 15 144 10.4 Group Y* 1 0 1 0 0 2 16 12.5 Serogroup not determined*

10 4 4 8 1 27 1171 2.3

Meningitis only 4 3 4 2 1 14 830 1.7 Septicaemia only 7 3 16 6 7 39 840 4.6 Meningitis and septicaemia

6 6 3 7 5 27 469 5.8

Isolation 13 14 22 10 9 68 1289 5.3 PCR 3 1 2 6 3 15 633 2.4 Gramneg 0 0 0 0 0 0 47 0.0 Latex 0 0 0 0 0 0 2 0.0 Throat 0 0 0 0 0 0 23 0.0 Probable 7 2 2 2 1 14 738 1.9 Total 23 17 26 18 13 97 2732 3.6

* 2003 and 2002 figures include serogroups determined by both isolation and PCR. Previous serogroup figures have only included isolation results.


Table 30. Case-fatality rates for confirmed cases meningococcal disease by age, gender, ethnicity and clinical description, 1999-2003

Features of Number of fatalities Case- case and infecting organism

1999

2000

2001

2002 2003

Total fatalities

99-03

Total cases 99-03

fatality rate (%)

<1 year 2 2 3 3 1 11 304 3.6 1-4 years 4 5 6 2 2 19 527 3.6 5-9 years 0 0 0 1 0 1 196 0.5 10-14 years 2 0 2 0 1 5 179 2.8 15-19 years 1 2 5 5 3 16 302 5.3 20-29 years 2 1 3 0 2 8 206 3.9 30-39 years 1 1 1 0 0 3 84 3.6 40+ years 4 4 4 5 3 20 173 11.6 Male 4 7 15 6 5 37 1082 3.4 Female 12 8 9 10 7 46 882 5.2 European 10 9 11 9 4 43 915 4.7 Maori 4 4 8 4 2 22 660 3.3 Pacific 2 2 4 2 3 13 326 4.0 Other 0 0 1 1 3 5 52 9.6 Unknown 0 0 0 0 0 0 18 0.0 Meningitis only 2 3 4 2 1 12 611 2.0

5 3 14 4 7 33 573 5.8 Meningitis and septicaemia

5 5 3 7 4 24 374 6.4

Total 16 15 24 13 12 69 1558 4.4

Septicaemia only


Table 31. Follow-up of contacts of meningococcal disease cases, 2003

Type of contact

Number of

cases for whom contacts were

identified

Number of

cases for whom contacts were

counselled

Number of cases for whom contacts were

offered vaccination

Household contacts 447 391 434 8 Day-care contacts 27 24 15 1 Room-mates in institutions

25 17 17 1

Contact with oral secretions

158 124 150 5

Other 96 80 48 3

Number of cases for whom contacts were

offered antibiotics

Table 32. Total number of contacts identified and offered counselling, antibiotics and vaccination, 2003 Type of contact

Total number

identified (range per case)

Total number

counselled (range per case)

Total number offered

antibiotics (range per case)

Total number offered

vaccination (range per case)

Household 3081 2644 2928 30 contacts (1-39) (1-33) (1-33) (1-16) Day-care 912 727 372 92 contacts (1-130) (1-86) (1-86) (92) Room-mates in 390 317 291 5 institutions (1-180) (1-180) (1-180) (5) Contact with 1114 868 1043 26 oral secretions (1-61) (1-61) (1-61) (1-11) Other 665 538 345 13 (1-94) (1-94) (1-94) (1-10) Total 6162 5094 4979 166



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