TRANSACTIONSOFTHEROYALSOCIETYOFTROPICALMEDICINEANDHYGIENE(2000)94,265-270

A severe epidemic of meningococcal meningitis in Nigeria, 1996

Idris Mohammed’*, Abdussalam Nasidi3, A. S. Alkali’, M. A. Garbati’, E. K. Ajayi-Obe’, Kudi A. Audu’, Abdulmumini Usman and Suleiman Abdullahi’ Departments of ‘Medicine and ‘Microbiology, University of Maidugwi, P.M.B. 1069, Bama Road, Maiduguri, Nigeria; Department of &ease Control and Intemanonal Health, Federal Ministy of Health, Abuja, Nigeria; 4Epidemiologikal Unit, Kano State Ministy of Health, Kano, Nigeria; ‘Infectious Diseases Hospital, Sabon Gari, Kano, Nigeria

Abstract A particularly severe epidemic of meningococcal meningitis (cerebrospinal meningitis, CSM) occurred in Nigeria between January and June 1996. There were 109 580 recorded cases and 11717 deaths, giving a case fatalitv rate of 10.7% overall. This is the most serious enidemic of CSM ever recorded in Nigeria, and may be thelargest in Africa this century. It took over 3 months and the combined efforts of a Nat&al Task Force set up by the Federal Ministry of Health, the WHO, UNICEF, UNDP, Medecins Sam Front&es, the International Red Cross and several other non-governmental organizations to bring the epidemic under control. The main control measures centred on active treatment of infected persons, mass vaccination and health education. The exact number of persons treated cannot be ascertained, but there were treatment centres in almost every Local Government Area in the affected States. A study of 1577 patients admitted at the Infectious Diseases Hospital, Kano, showed that 84% ofthose infected were aged s20 years and that, for the first time, infants aged ~2 months were affected. Despite intervention, the case fatality rate of 9.1% among this group of patients was similar to the nationwide figure of 10.7%. Long-acting oily chloramphe- nicol proved highly effective in the treatment of patients, and its routine use in epidemic CSM is recommended. Over 13 million persons were vaccinated in the course of the epidemic. For the first time, cases of CSM were reported from States south of the ‘African meningitis belt’, suggesting an extension of the belt. The severity of this epidemic yet again underscores the need for a clear policy regarding control measures aimed at forestalling future epidemics. The availability of the recently developed polysaccharide- protein conjugate vaccine should facilitate a decision on mass vaccination for the prevention of epidemic CSM in Africa.

Keywords: meningitis, Neisseria ;meningitidis, epidemiology, epidemic, mortality, disease control, chloramphenicol, vaccination, Nigeria

Introduction The first outbreak of meningococcal meningitis (cere-

brospinal meningitis, CSM) in Africa occurred in Algeria in 1840 (CHALMERS & O’FARRELL, 19 16). Epidemics in West Africa were reported later, in the Cape Coast in the late 19th and early 20th centuries (WILLIAMS & WIL- LIAMS, 1900, 1901). These epidemics ofmeningococcal meningitis continue to occur in sub-Saharan Africa despite the knowledge that they can be controlled by a properly designed chemoprophylaxis regimen (VOLLUM & GRIFFITHS, 1962; BIAKEBROUGH & GILLES, 1980), and a well-executed immunization programme (ARTEN- STEIN et al., 1970; WAHDAN et al., 1973; ETTORI et al., 1977; GREENWOOD & WALI, 1980; MOHAMMED & ZARUBA, 198 1). Sulphonamides, penicillin, chloram- phenicol and rifampicin have been used to good effect in reducing meningococcal carriage in the nasopharynx, a factor in preventing outbreaks, although the potential costs would militate against their use in co-ntrolling eoidemics of CSM (GREENWOOD. 1999). Vaccination appears to hold the best promise for ultimate control of epidemic meningococcal disease. Earlier trials of menin- gococcal vaccines produced inconclusive or disappoint- ing results, either because the trials were not properly conducted or because the vaccines used were poorly immunogenic (DAVIS, 1931; RIDING & CORKHILL, 1932). Groups A & C polysaccharide vaccines developed later were more immunogenic in adults (GOLDSCHNEI- ~~~etal., 1969; GREENWOOD etal., 1980), but less soin infants and young children (MONT0 et &., 1973; PEL- TOLA et al, 1977; MOHAMMED & DAMISAH. 1982). In recent years mass vaccination using groups A & C meningococcal polysaccharide vaccines has been carried out in several States in northern Nigeria with fairly good results (MOHAMMED & ZARUBA, 198 1; MOHAMMED et al., 198‘4a, 1984b). Sustained routine mass vaccination with currently available bivalent vaccines, backed up by

*Author for correspondence: e-mail maiduguri-lab@who.nigeria.org

selective vaccination during outbreaks, might have pre- vented this outbreak, or limited its scale.

Five major epidemics of CSM have occurred in nortb- em Nigeria in the past 30 years, in 1970, 1975, 1977, 1986 and 1996. The 1996 epidemic is the severest of them all and is the subject of this paper. It was preceded by similar epidemics in Chad (1988), and Niger Republic (1991,1994), both countries neighbouring Nigeria. The same strain, Neisseria meningitid&, sero-group-A, clonal LOUD X11.1, was resnonsible for the outbreak in those countries (WHO, 1995), and is the same as that which caused epidemics in Nepal in 1983 (COCHI et al., 1987) and Saudi Arabia in 1987 (MOORE, 1992), and may have been introduced to Africa by pilgrims returning home from that country. There is some evidence that this strain of meningococcus was introduced to Nigeria from Niger Republic through Jibia, the border town in Katsina State which is some 30 kilometers from Maradi.

The factors responsible for the severity of this epi- demic are not clearly known, but the outbreak occurred in the hot, dry and dusty season when the absolute humidity was also low. Herd immunity in the general population was probably low since vaccination coverage in the preceding 2 years had been low (Federal Ep’l- demiological Unit. nersonal communication). Poor en- vironmental condi&ns facilitated the rapid &read of the epidemic, as the majority of those infected were of low socio-economic status living in over-crowded, poorly ventilated and dirtv dwellinas. The strain of meninno- coccus responsible for the-epidemic was new to &e region, and its virulence may have been due in part to an inability to mount an effective immune response.

Features of the epidemic A formal report of the outbreak was made to the

Epidemiological Unit of the Federal Ministry of Health at the end of February 1996. However, the record books of several Local Government health units show that cases of meningitis had been diagnosed with increasing fre- quency as far back as October 1995. In a rural health centre at Jibia, a town in north-western Nigeria bordering Niger Republic, the epidemic threshold (15 cases per

100 000 population for 2 consecutive weeks) had been reached in November 1995.

The organism A total of 467 cerebrospinal fluid specimens from

patients aged 3 months to 30 years (260 males, 207 females) in 6 States (Bauchi, Kaduna, Kano, Katsina, Kebbi and Yobe) were subjected to latex agglutination (test kits kindlv donated bv the International Red Cross). and culture. Of these, 288*were positive on culture for G meningitidis (173 males, 115 females); 432 (245 males, 187 females) were positive for N. meningz’tidis group A on latex agglutination. None of the specimens was positive for group B or C meningococcus, or Streptococcus pneumona’ae. Three samples were positive for Haemophi- lus injruenzae on latex agglutination. Clonal identification of the organism done at the National Institute of Public Health, Oslo, Norway, by courtesy of Dr Francis Varaine (Medecins Sam Front&es, MSF), showed that the organism responsible for the epidemic was N. meningi- tidis. seroaroun A clonal sub-frroun III. 1. The low posctivity & culture (61.7%) is”moit probably due to antibiotic self-medication before arrival in hospital, a well-known phenomenon in Africa.

Climatic conditions The epidemic started in January and reached its peak

in mid-April when it was extremely dry and dusty, and the average ambient temperature (Department of Meteorological Services, Nigeria) was 39.3”C (range 37-42°C). The relative humidity was 30.2% (range lo-65%). The highest ambient temperature and the lowest relative humidity were recorded in March, April and May, at the peak of the epidemic. The situation was compounded by the fact that most of the population of the affected States lived in poorly ventilated, over- crowded rooms where the internal room temperature could rise above 45°C during daylight. The first rains were recorded in mid-May 1996.

Dynamics of the epidemic The epidemic threshold was reached in the 4th week of

February in most States, and once it had taken hold, the outbreak spread across most ofnorthem Nigeria within 2

IDRIS MOHAMMED ETAL.

weeks. The States most affected are those in the heart of the African meningitis belt, namely, Katsina, Sokoto, Kebbi, Kano, Niger, Kaduna, Jigawa, Bauchi, Yobe and Bomo (Fig. 1). Four of these States (Bauchi, Kano, Katsina and Kebbi) between them accounted for 8 1230 (74.1%) of the cases renorted. The attack rate ranged &om 8 ‘to 1000 as sho& in Figure 1. States sucg as Adamawa, Taraba, Plateau and Kwara lie just outside the meningitis belt, and the attack rate of 21 to 200 in these States is consistent with previous findings (MO- HAMMED et al., 1984a). Importantly, cases were reported from States as far south as Ogtm, Delta, Cross River and Enugu, several hundred kilometers from the belt.

The epidemic curve Figure 2 shows the epidemic curve from week 4 (end of

January) to week 22 (beginning of June). A dramatic rise in the number of reported cases began in weeks 9/10, the epidemic reaching a peak in week 14 when 16 026 cases were reported. This was followed by a rapid decline in the number of cases in weeks 15 to 19, and only 25 cases were reported in week 2 1, and none in week 22. It is of note in

T V Onset of Rains

my\ 20 1 1 1 5 X

4 5 6 7 8 9 10111213141516171819202122 Time (weeks)

Fig. 2. The meningococcal meningitis epidemic curve for Ni- geria, 1996. Arrows indicate timing of intervention components in relation to the epidemic curve. T, treatment; V, vaccination.

Attack rate/l 00 000 j$j@ g-20

m 21-200

m 201-500

Fig. 1. Map ofNigeria showing attackrate from meningococcal meningitis in affected States (numbered l-21) in the 1996 epidemic. 1, Kebbi; 2, Sokoto; 3, Katsina; 4, Kano; 5, Jigawa; 6, Bauchi; 7, Yobe; 8, Borno; 9, Niger; 10, Kaduna; 11, Adamawa; 12, Kwara; 13, Kogi; 14, Plateau; 15, Taraba; 16, Osun; 17, Edo; 18, Enugu; 19, Cross River; 20, Ogun; 2 1, Delta.

MFJNINGOCOCCAL MENINGITIS IN NIGERIA 267

relation to the epidemic curve that therapeutic interven- tion and mass vaccination began in weeks 9 (early March) and 10 (mid-March) respectively, whilst the rains began to fall in week 17 (early May).

Age and sex

na, Niger and Sokoto States had vaccinated about 20% of the susceptible population in 1994 and 1995, but the other States of Nigeria in the meningitis belt had hardly vaccinated anybody. The complacency might have been engendered by the fact that the number of cases and deaths from CSM had remained low since 1990.

Accurate information on age and sex was available for 64 130 patients. Of these, 35 356 were male, making the male:female (M:F) ratio 1.2: 1 (Table 1). There were 750 patients aged less than 12 months (M:F ratio 1.2:1). Seventy-two percent of the patients were aged O-15 years (26 532 males, 19 622 females; M:F ratio 1.4: 1). A total of 7074 patients were aged 2 30 years, and as the age-group affected approached 30 years the M:F ratio became unity.

Intervention to control the epidemic

Case-fatality rate There were 109 580 reported cases and 117 17 deaths,

giving a case-fatality rate (CFR) of 1097%. A more detailed analysis of the data from the 4 most affected States (Table 2) shows that as the epidemic progressed the CFR fell progressively in each of the States. The average CFR for the 4 States fell from 22.1% in the first 10 weeks to 14.8% in the second 10 weeks and 4.8% in the last 10 weeks of the epidemic. The overall CFR for the 4 States (10.5%) was similar to the overall CFR of 10.7% nationwide.

The Federal Ministry of Health set up a special Task Force (headed by one of us, I. M.) to coordinate control activities in all the States affected. Volunteers joined the Task Force and, together with State and Local Govem- ments, a massive treatment and vaccination campaign was mounted. International organizations such as the WHO, UNICEF, and UNDP provided materials and logistic support. Training workshops were organized with strong support from the WHO whose country representative took active part in the control effort. Medecins Sans Front&es (MSF) and the International Red Cross also provided material and logistic support, and both aid organizations participated actively in the vaccination exercise and therapeutic activities in the treatment centres.

Therapeutic intervention

Pre-epidemic vaccination status Information from the Federal Epidemiological Unit

shows that most of the States did not undertake any significant vaccination of the population in the 2 years preceding the outbreak. Borno, Yobe, Adamawa, Kadu-

Table 1. Age and sex distribution of cases of me- ningococcal meningitis in Nigeria in the 1996 epi- demic

Age-group (years) <l l-5 6-15 16-29 30+ Total

Male Female M:F ratio

402 348 1.2 8610 6012 1.4

17 520 13 262 1.3 5503 5399 1.0 3321 3753 0.9

35 356 28 774 1.2

Treatment centres were established in every Local Government Area (LGA) in the affected States early in March. These consisted in the main of improvized facilities in the outskirts of towns and villages, with patients lying on unpaved bare floor. Most of these treatment centres were manned by little-trained para- medical staff such as community health workers. Several of the facilities located in bigger towns and cities had nursing staff, but few were directly managed or super- vised by doctors. Government hospitals (including some teaching hospitals) provided space for management of some ofthe patients, but their contribution was marginal. It is difficult to determine how many of the 109 580 reported cases received treatment, but most of them did. The use of oily chloramphenicol was widely advocated during emergency training workshops for LGA and State health workers, but the drug (largely donated by the WHO, MSF and the International Red Cross) was not available in sufficient quantity. However, most patients in Kano, Bauchi, Katsina, and Jigawa States were treated with oily chloramphenicol with good results. The use of this drug was limited in the other States, where more

Table 2. Number of cases, deaths and case-fatality rates (CFR) for the 4 States most affected by the 1996 Nigerian meningococcal meningitis epi- demic

Weeks

State

Bauchi Cases (n) Deaths (n) CFR (%)

Kano Cases (n) Deaths (n) CFR (%)

Katsina Cases (n) Deaths (n) CFR (%)

Kebbi Cases (n) Deaths (n) CFR (%)

45 (1995)- 2 (1996)- 12 (1996)- Average 1 (1996) 11 (1996) 21 (1996) CFR (%)

162 13079 5400 46 2165 452 28.4 16.6 8.4 14.3

687 13 703 10 172 160 867 345 23.3 6.3 3.4 5.6

931 9138 10858 219 1448 837 23.5 15.8 7.7 12.0

684 8550 7866 151 1265 375 22.1 14.8 4.8 10.5

IDRIS MOHAMMED ETAL.

conventional antibiotics (benzylpenicillin and ampicil- lin) were mainly used.

Vaccination activities A massive vaccination campaign was mounted under

the guidance of the Federal Task Force in the 10th week of the epidemic. This campaign had been carefully designed in close consultation with all those actively involved: the WHO, MSF, the Red Cross and officials of State and Local Governments. Immediate attention was given to the States most affected, i.e., Kano, Katsina and Bauchi. The Federal authorities had earlier procured 12 million doses of bivalent (groups A & C) vaccines from Pasteur-Merieux, France, and 10 million doses were distributed to the States. The States provided other supplies, logistic support and vaccinators, who went village by village on bicycles, motor cycles and horse back conducting the exercise. Members of the Task Force went round State by State supervising the conduct of the exercise, and providing on-the-spot training. There was a dearth of supplies, particularly of syringes and needles, which made it necessary to use ‘red-o-Jet injectors (Vemitron, Carlstatdt, NY, USA) for vaccinat- ing most of the people. These are manually operated jet injectors which deliver 05 mL of the vaccine into the deltoid muscle of the arm. The nozzle is placed about 1 cm from the skin surface (no contact is allowed), but inaccurate application often results in physical contact and bleeding, raising concerns about transmission of infectious agents such as hepatitis viruses and HIV. However. in Bauchi. Kano. Katsina. Tiaawa. Sokoto and Kebbi States where MSF and &eYInternational Red Cross conducted part of the vaccination, disposable syringes and needles -supplied by these orgamzations were mostlv used. Overall. 13.4 million neoule were vaccinated *before the epidemic was brought under control. Of these, 6.3 million were in the 4 States with the highest number of cases (Kano, Katsina, Bauchi, Kebbi). A total of 95 million neonle were vaccinated bv the States, 3 million by the MSk (i.4 million in Kano, 0.8 million each in Bauchi and Katsina), and 0.93 million by the International Red Cross ( 059 million in Jigawa, 0.17 million each in Kebbi and Sokoto). There were no reports of any untoward reactions to the vaccine used throughout the country. As vaccination and antibiotic treatment progressed, the number of reported cases fell, and the illness became milder, so that by the 16th week the total number of reported cases nationwide had dropped to 8750 per week, and the case-fatality rate from 24.3% to 6.0%.

Clinical features The main clinical features of the epidemic were stud-

ied in 1577 patients admitted at the Infectious Diseases Hospital, Kano. The M:F ratio was 15:l. Eighty-four percent of the patients (1325) were aged G20 years, 473 (30%) were aged 6-10 years, and, significantly, 300 (19%) were aged O-5 years, among whom were infants aged ~2 months. Treatment with antibiotics was given to 1544 patients, of whom 1404 recovered and 140 died (CFR 9.1%). A total of 1243 natients were treated with a single injec’tion of oily chloramphenicol-10 10 with Tifomycine (Roussel), 233 with Astrapin (Pharmazeu- tische Praparate Dr Klaus Hoffman GmBH & Co. KG)-of whom 1118 recovered and 125 died (CFR 10.1%). Of the remainder, 146 patients received oily chloramphenicol plus benzylpenicillin (CFR 6.5%), 124 received benzylpenicillin alone (CFR 98%), and only 3 1 were treated with ampicillin alone (CFR 17.9%). An analysis of the age-specific CFRs among those treated with oily chloramphenicol (Fig. 3) shows that the highest CFR was in those aged > 3 1 years (CFR 19.6%), and the lowest (CFR 5.4%) was in those aged 11-15 years and 26-30 years. The CFR among patients aged O-5 years was 12.4%. Mortality was highest among patients who presented with meningococcaemia and circulatory fail- ure.

Discussion This epidemic of meningococcal meningitis is by far

the severest in recorded history in Nigeria, and may well be the largest in Africa this century. It was caused by A? meningitidis, serogroup A, clonal sub-group III. 1. Several factors may have contributed to the scale and severity of the epidemic, among them low herd immunity as a result of non-vaccination. The socio-economic circumstances of Nigerians had deteriorated so much in the preceding 10 years that the living conditions at the time of the outbreak were highly conducive to the rapid spread of epidemics such as the one that occurred. The climatic conditions must also have contributed to the spread since temperatures were as high as 45°C the atmosphere dry and dusty, and the absolute humidity very low. Whether these effects are attributable to the El Nirio phenomenon remains open to speculation. The particular strain of N. meningitidis responsible for the epidemic (serogroup A, clonal sub-group 111.1) was new to Nigeria, and its virulence must have had an important bearing on the severity of the outbreak.

The exact scale of this epidemic is unknown, since only a proportion of families take their ill relatives to hospital during outbreaks, either because of ignorance or for fear of being stigmatized. The reported figure of 109 580

0 o-5 6-10 11-15 16-20 21-25 26-30 31+

Age-group (years)

Fig. 3. Outcome of treatment of meningococcal meningitis with oily chloramphenicol by age-group (Nigeria, 1996).

MENINGOCOCCAL MENINGITIS IN NIGERIA 269

cases is thus only the tip of the iceberg, as under- reporting is common (GREENWOOD, 1999). Several observers believe that to get nearer the true figure the number of reported cases should be multiplied by a factor of 10 at least. The same applies to the number who died. During visits to States and local governments we saw several mass graves containing hundreds of bodies of victims who were buried secretly.

Several features of this epidemic point to a change in the clinical and epidemiological pattern of CSM in Africa. The age-group affected most in previous African epidemics was 5-15 years (BELCHER et al., 1977; GREENWOOD et al.. 1979). In this enidemic a substantial number of childrenaged i5 years were affected, and 750 were aged C 1 year, some of them infants of C2 months. A similarnumber of patients aged 5 16 years was recorded, with 7074 axed 230 vears. The reasons for this widening of the age-groups affected are not clear, but the reported virulence of the clonal sub-group III.1 strain of the meningococcus may have contributed to some extent. The overall male to female ratio is consistent with previous findings, but it is interesting that the ratio among patients aged a-16 years was unity. This may indicate that men and women of this age-group lead similar lifestyles which exposes them to infection equally. It is not certain why the epidemic extended southwards outside the traditional meningitis belt, but the fact that cases of CSM were reported from States as far south as Delta, Ogun and Cross River suggests that a redefinition of the African meningitis belt at this time might be in order.

The epidemic curve followed a similar pattern to previous ones, but intervention by way of treatment of cases and mass vaccination (see timing in Fig. 2) helped in dramatically reducing the number of cases and deaths between weeks 16 and 19. The onset of the first rains led to termination of the epidemic, as usual (GREENWOOD, 1999). Although the epidemic was not reported to the Federal health authorities until February, cases sugges- tive of an impending outbreak were recorded as early as November 1995 in a town bordering Niger Republic. This suggests that in all probability the organism was imported from that neighbouring country since the same strain of the meningococcus was responsible for an earlier epidemic there (RLTMEIJER, 1996), which was itself preceded by others in Nepal, India and Saudi Arabia (MOORE et al., 1989). The epidemic curve also illustrates the degree of failure of the surveillance system in Nigeria, where an epidemic preparedness and re- sponse mechanism has failed to take off properly.

The response to antibiotic therapy was quite good. The results of this studv show that treatment with a single injection of oily chloramphenicol (Tifomycine or A&a- pin) was highly effective in this epidemic. This observa- tion confirms earlier findings (REY et al., 1975; WAU et al., 1979; PECOUL et al., 199 l), and represents a major advance in the management of epidemic meningococcal meningitis in Africa, since little-trained personnel can be engaged to render treatment during epidemics. There were 146 patients who failed to show adequate response to oily chloramphenicol, but there was no evidence from this study to suggest the development of resistance to the drug. Rather, we feel that the inadequate response was due to the fact that the patients were unsuitable for treatment with this agent, as shown by the prompt and satisfactory response to benzylpenicillin given as substi- tute. Oily chloramphenicol has now fully established itself as the cornerstone of therapeutic intervention in epidemic meningococcal disease, and its routine use is highly recommended.

The morbidity and mortality in this epidemic were broadly similar to those in previous epidemics in Africa (BWALA et al., 1989; GREENWOOD, 1999), but are almost certainly underestimated because many septicae- mic patients die before reaching hospital (GREENWOOD et al., 1987). There were several reports, confirmed by

members of the task force, of people burying their dead secretly within compounds or in make-shift burial grounds. Despite these observations, the intervention measures during the epidemic must have contributed to the low morbidity and mortality. Vaccination with groups A and C vaccines has been effective in controlling epidemics of CSM when undertaken very early (GREEN- WOOD & WALI, 1980; MOHAMMED & ZARUBA, 1981; BINKIN 8z BAND, 1982), despite the fact that the currently available bivalent (groups A & C) vaccines are poorly immunogenic, particularly in younger chil- dren (MONTO et al., 1973; PELTOLA et al., 1977), because polysaccharide antigens are T-cell independent. The recent development of polysaccharide-protein con- jugate vaccines which are already undergoing trial is believed to be a major advance in the control of epidemic meningococcal disease because they induce strong im- munity in young infants, as well as long-lasting T-cell- dependent immunological memory (GREENWOOD, 1999).

An important problem of mass vaccination in Africa is the inadequate supply of syringes and needles, necessi- tating the use of ‘red-o-Jet injectors for vaccination, as happened during this epidemic. We may never know how many infectious agents (including hepatitis B and C viruses and HIV) were transmitted as a result of using: these injectors, but clearly their use must be stopped ai soon as practicable. It has also been observed that mass vaccination after an outbreak is unlikely to reduce the number of epidemic cases by more than half (HAELTER- MAN et al., 1996; VARAINE et al., 1997). This observation underscores once again the need for a definite policy on mass vaccination to prevent epidemics of CSM in Africa. Proper coordination among all the countries within the meningitis belt is necessary, to ensure successful control of epidemics in the region. The financial burden on countries in the region is likely to be high, but mass vaccination need not be undertaken yearly, since several trials have shown that adequate antibody responses are induced by these vaccines (GOLDSCHNEIDER et al., 1969; GREENWOOD et al., 1980) which may remain high for up to 4 years in persons aged 35 years (MOHAMMED et al., 1984b). Thus mass vaccination may need to be carried out only every 3 years.

Acknowledgements We gratefully acknowledge the valuable contributions of all

those who volunteered to work with the Task Force in control- ling this epidemic. We are particularly grateful to the WHO (Nigeria) and Dr E. K. Njelesani who provided vaccines, antibiotics, syringes and needles, as well as ‘Ped-o-Jet’ injectors. The WHO also organized workshops for State and local Government health personnel during the epidemic. The UNDP and UNICEF provided material and logistic support. The MSF and International Red Cross supplied vaccines, oily chloram- phenicol, syringes and needles, and also actively participated in the vaccination campaign and treatment of patients. The Federal Ministry of Health urovided most of the vaccines. some antibiotics, sv&aes and needles. ‘Ped-o-let’ iniectok. and logistic suppdrt. We are grateful to’the Kano”State ijovemment for accommodating members of the Task Force, and to the other State Governments we visited for their hospitality.

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Received 9 August 1999; revised 27 October 1999; accepted for publication 17 November 1999