GB Emerging Threats

Quarterly Report

Avian Diseases

Safeguarding

public and

animal health

editor:

tel:

email:

David Welchman, APHA Winchester

+ 44 (0) 1962 779966

David.welchman@apha.gsi.gov.uk

Quarterly Report: Vol 20 : Q1 January– March 2016

Contents Page

Introduction & overview of chick and poult placings 2

New & re-emerging diseases and threats 4

Ongoing new and re-emerging disease investigations 8

Unusual diagnoses 10

Horizon scanning 10

Diagnostic submission trends 11

References 13

Highlights Page

Notifiable Avian Disease including Testing To Exclude; Differential diagnosis of negated Noitifiable Avian Disease cases

4

Histomonosis update 8

Gizzard erosion in broilers and layers 9

Horizon scanning – ‘white chicks’ 10

VIDA diagnoses are recorded on the APHA FarmFile database and SAC Consultancy: Veterinary Services LIMS database and comply with agreed diagnostic criteria against which regular validations and audits are undertaken. The investigational expertise and comprehensive diagnostic laboratory facilities of both APHA and SAC C VS are widely acknowledged, and unusual disease problems tend to be referred to either. However recognised conditions where there is either no diagnostic test, or for which a clinical diagnosis offers sufficient specificity to negate the need for laboratory investigation, are unlikely to be represented. The report may therefore be biased in favour of unusual incidents or those diseases that require laboratory investigation for confirmation. APHA VICs have UKAS Accreditation and comply with ISO 17025 standard. SAC C VS have UKAS accreditation at their central diagnostic laboratory and at the Aberdeen, Edinburgh, Perth, Ayr, Dumfries, Inverness, St Boswells and Thurso Disease Surveillance Centres which comply with ISO 17025 standard. From September 2014 APHA contracted the services of partner Post Mortem providers. From April 2015, these services were provided by the Royal Veterinary College, the University of Bristol, University of Surrey, Wales Veterinary Science Centre and SACCVS. These providers contribute to the VIDA diagnoses recorded on the APHA FarmFile database and comply with agreed diagnostic criteria. To achieve a VIDA diagnosis, all testing must be carried out by a laboratory with ISO 17025 accreditation.

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INTRODUCTION

This report contains analysis of animal health and scanning surveillance data and information from APHA, SAC Consulting Veterinary Services (SAC CVS) and non-APHA partner post-mortem providers (SAC CVS, University of Bristol, Royal Veterinary College, University of Surrey (four sites), Wales Veterinary Science Centre, Aberystwyth) from the first quarter of 2016 compared to data in previous quarters and years. The network of partner post mortem providers is developing, and the current providers and sites have commenced activity at various times between September 2014 and July 2015. The report is compiled by the APHA Avian Expert Group, and is based on diagnostic submissions as well as on surveillance data and information from other sources. It is planned for the latter two to be expanded with time as other sources of complementary information are included. These scanning surveillance activities aim to provide timely detection of animal-related new and re-emerging diseases and threats. The information contained in this report, and other linked outputs, is used by government, the livestock industry, farmers and vets to maintain awareness and take action to manage risks that may be associated with the identified threats. Further information can be found at: http://ahvla.defra.gov.uk/vet-gateway/surveillance/index.htm.

OVERVIEW

Industry trends – chick and poult placings Broilers There was a 3.3% increase in placings of broiler chicks from UK hatcheries during March 2016 compared with March 2015, at 76.8 million chicks (Fig. 1), indicating continued growth in the broiler sector.

Figure 1: Average number of broiler chicks placed per week in the UK from UK hatcheries

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Turkeys There was a decline of 3.9% in the number of turkey poults placed during March 2016 compared to March 2015, at 0.9 million. This reflects a continued fluctuation in turkey poult placings.

Figure 2: Average number of turkey poults placed per week in the UK by UK hatcheries

Layers The number of layer chicks placed during March 2016 was 11% lower than the corresponding figure for March 2015, at 2.9 million chicks (Fig 3), but the projected size of the UK laying flock remains at a high level compared to recent years. UK packing station egg throughput in Q1-2016, at 7.2 million cases, was 5.1% higher than in Q1-2015, and 0.4 % higher than in the preceding quarter. Free range eggs accounted for 45.4% of eggs packed in Q1-2016, and 44.2% for 2015 as a whole. Average UK farm gate prices for eggs declined in Q1-2016 compared to both Q1-2015 and the preceding quarter; there is concern that the increase in egg supply may result in continued downward pressure on egg prices, despite an increase in per capita consumption especially of free range eggs.

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Figure 3: Average number of layer chicks placed per week in the UK by UK hatcheries

The poultry industry statistics are available online at: ● Poultry and poultry meat statistics:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/518879/poultry-statsnotice-21apr16.pdf [accessed 11 May 2016]

Egg statistics: https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/520971/eggs-statsnotice-05may2016.pdf [accessed 11 May 2016]

The comments are supplemented by reports from industry and Poultry World.

NEW AND RE-EMERGING DISEASES AND THREATS

Monitoring the trends in diagnoses of known diseases cannot, by definition, detect either new diseases or changes in endemic diseases that would prevent a diagnosis from being reached (for example a change in the pathogen that compromised the usual diagnostic test). Such new or emerging diseases would probably first be detected by observation of increased numbers of submissions for clinical and/or pathological syndromes for which a diagnosis could not be reached in the normal way.

Data recording by APHA and SAC was harmonised from 2007.

Notifiable avian disease

HPAI and LPAI outbreaks in Europe

During Q1-2016, GB experienced an outbreak of H5N1 Low Pathogenicity Avian Influenza (LPAI) in a farm of 40,000, 57-week-old broiler breeders in Scotland. The LPAI was detected through the Notifiable Avian Disease Exclusion Testing Scheme (see below). The most likely source of LPAI was considered to

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be wild birds, as confirmed by genetic sequence analysis and epidemiological investigations. Phylogenetic analysis indicated that the influenza strain involved was not the same as those reported in France (H5N1 Highly Pathogenic Avian Influenza, HPAI) but was related to previous H5N1 LPAI outbreaks in Italy and Germany in 2014. A preliminary outbreak assessment dated 14 January (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/492900/poa-lpai-UK-20160114.pdf accessed 13 May) noted that ‘We consider that there is a constant low risk of incursion of any notifiable avian disease into the poultry in the UK from direct or indirect contact with wild birds. Prompt reporting of disease by farmers and vets in the UK, rapid diagnosis and swift disease control measures, often in advance of final strain identification, as in this case, enables rapid eradication from the UK poultry flock. The risk to public health and food safety is negligible.’

Outbreaks of H5 HPAI in south-west France, first confirmed in a hobby flock on 24th November 2015 (APHA 2015), have been confirmed on 74 premises by 29th February 2016, involving three H5 subtypes (H5N1, H5N2 and H5N9) in some cases in combination. Outbreaks of H5 LPAI have also been reported involving two H5 subtypes (H5N2 and H5N3). The location of the H5 HPAI outbreaks is shown below, with the blue coloured area indicating the restriction zone (Fig.4)

Figure 4: Location of 74 outbreaks of Highly Pathogenic Avian Influenza in France to 29 February 2016

In 27 clinical outbreaks the mortality seen in galliformes reached a higher level than in anseriformes, but mortality in the latter was sometimes as high as the mid-twenties %. There was no difference reported in mortality rates caused by the different N-subtypes of H5 HPAI (Fig. 5)

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Figure 5: Observed mortality in H5 HPAI outbreaks in anseriformes and galliformes in France to 29 February 2016

A Defra updated outbreak assessment on HPAI in France dated 18th February (https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/501957/poa-hpai-france-update-20160218.pdf accessed 13 May) concluded that ‘The outbreaks have, for the large part, been restricted to the fattening duck production system with occasional spill-over into other farms in close proximity and likely fomite transfer. The eradication programme is a positive move by the French Authorities to give confidence to the consumer and trade partners.

‘There remain some uncertainties around the evolution of low pathogenic European strain viruses into these highly pathogenic strains, including the viral sequences and tissue tropism which will inform the transmission dynamics and potential to spill over into wild birds. Furthermore, the evolution of the HPAI virus as it spread remains to be defined including the precise pathways that resulted in the emergence of three HPAI virus subtypes in an apparently similar timeframe.

‘The risk to the UK has not increased as a result of the new outbreaks reported. However the situation in France simply reinforces what we already knew, that these LPAI viruses circulate in wild birds and cause occasional spill-over outbreaks in poultry which may be difficult to detect in domestic waterfowl species and which may then mutate into HPAI viruses following infection of galliforme hosts.

‘We will continue to monitor the situation closely. We would like to remind all poultry keepers to maintain high standards of biosecurity, remain vigilant and report any suspect clinical signs promptly and in addition using the testing to exclude scheme for avian notifiable disease where appropriate for early safeguard. For more information, please see www.defra.gov.uk/ahvla-en/disease-control/nad’

There were no reports of HPAI in wild birds in The European Union in the first quarter of 2016.

Information on the AI outbreaks and situation described was taken from: http://ec.europa.eu/food/animals/health/regulatory_committee/presentations_en.htm#03022009 (accessed 13 May 2016).

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Newcastle disease in Europe

Newcastle disease was confirmed in several backyard flocks in two villages in southern Bulgaria on 5th and 23rd February.

GB avian notifiable disease exclusion testing scheme

The scheme started in May 2014 (Gibbens and others 2014) and is continuing (http://ahvla.defra.gov.uk/vet-gateway/nad/index.htm; accessed 16 May 2016). There were two exclusion testing investigations during Q1-2016, with results as shown below (Table 1). The scheme is invaluable in enabling LPAI to be investigated where it is considered to be a differential diagnosis in the clinical signs seen in birds on a site. Table 1: Summary of findings from the Notifiable avian Disease Exclusion Testing Scheme, Q1-2016

Species and

purpose (where

information

available)

Clinical details Cloacal and

oropharynge

al swabs

taken

Results Outcome

Chickens – broiler

breeders

(8 January)

A drop in egg production started

in one house on January 3rd,

associated with increased water

intake and less interest in feed

(slower 'clean up'). There was

also loss of shell colour.

Otherwise, no increases in shell

defects. Production was 57% on

January 2nd and 33% on

January 4th. The other house

was the adjoining air-space,

across the service area,

showing signs similar to the start

of the issue in the first house.

Mortality was almost normal.

Yes Positive

M-gene

(AI virus)

PCR

results.

Avian Notifiable

Disease not

excluded. Led to

detection of

H5N1 LPAI

(DPR2016/01)

Turkeys (10

March)

Owner reported that

one of the turkeys

had died the previous week &

had a cyanotic wattle & some

respiratory signs

Yes Negative

M-gene

PCR

results

Avian Notifiable

Disease

excluded.

Differential diagnosis of negated Notifiable Avian Disease cases An opportunity for differential diagnostic testing of a negated NAD case was taken during the quarter. Suspicion of notifiable disease was reported in a commercial broiler flock aged 17 days, in which there had been an increase in mortality (from 6 to 8%) over 24 hours accompanied by sinusitis, conjunctivitis and swollen heads. Samples were collected for statutory testing, resulting in negation of notifiable disease. Histopathological and other examinations of non-statutory samples collected under licence during the investigation demonstrated subcutaneous oedema which accounted for the swollen heads,

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but the underlying cause was not determined and may have related to a hypersensitivity or irritant reaction of unknown origin. There was also evidence of Escherichia coli bacteraemia/septicaemia. Although no underlying aetiology was demonstrated in this investigation, the opportunity for further investigation of negated report cases would be invaluable in understanding possible underlying disease processes which may trigger suspicion of notifiable disease. Formalising the procedure for this, and determining a process to select cases for which further investigation is appropriate, will be explored further.

Pigeon paramyxovirus investigations There were two submissions of material from pigeons to APHA Weybridge during the quarter for pigeon paramyxovirus testing as part of notifiable disease examinations. PPMV-1 was confirmed in both cases, both of which were in January. A submission of samples was also received for export testing, but PPMV-1 was not demonstrated.

ONGOING NEW AND RE-EMERGING DISEASE INVESTIGATIONS

Histomonosis - update The number of VIDA diagnoses of blackhead (histomonosis) by APHA and its partner post mortem providers in chickens in Q1-2016 was higher than Q1-2015 (Fig 6). Previous reports (APHA 2014, 2015) have highlighted the apparent increase of this disease in chickens, both in the UK and Europe, where it is regarded as a re-emerging disease (Hess and others 2015). In chickens the disease occurs in various production systems including free range layers, housed broiler breeders and back yard chickens. In the absence of licensed products to control the disease, the quest for new intervention strategies is continuing, including the possible use of vaccination to control the disease (see under horizon scanning below). Histomonosis will continue to be monitored by means of scanning surveillance. Figure 6: Incidents of blackhead in chickens as a percentage of diagnosable submissions in Q1-2016

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Histomonosis and colisepticaemia in organic layer chickens

Blackhead with concurrent E. coli septicaemia and acute peritonitis was diagnosed in two flocks together comprising 12,000, 22-week-old free range organic layers. After initially doing well, there had been a recent mortality of 12 birds, a drop in egg production of 10 per cent and slight weight loss. Post-mortem examination of birds which died naturally revealed casts of necrotic and caseous material in the caecum and splenomegaly variably associated with fibrinous peritonitis, perihepatitis and pericarditis. Target-like liver lesions were detected in a small number of birds. Bacterial cultures of livers and spleens yielded heavy pure growths of E coli. Histopathological examination of caecum and liver tissues revealed fibrinonecrotising lesions associated with histomonad-like organisms consistent with histomonosis (blackhead). Histomonosis had been recognised on the farm two years previously, and it is likely that the causative Histomonas meleagridis organism had persisted on the farm either in Heterakis species nematode eggs or earthworms. These birds also demonstrated coinfection with E. coli, which has previously been recognised as a cause of mortality in Histomonas-infected organic layer flocks. Histomonosis may in fact predispose birds to secondary colisepticaemia (Stokholm and others 2010). Following the diagnosis, the flock was given supportive treatment. There remain no licensed products available for the treatment of histomonosis and the condition is increasingly being recognised in chickens, as described, as well as in turkeys.

Avian Salpingitis-Peritonitis Disease

This disease complex (also referred to by terms such as salpingitis/peritonitis/salpingoperitonitis; egg peritonitis) is commonly diagnosed in layer and breeder chickens, and is a cause of significant economic loss worldwide. Six VIDA diagnoses were recorded during Q1; for example it was diagnosed in submissions of free range layers between 42 and 53 weeks of age with a history of a slight increase in mortality, and in 31-week-old broiler breeders with a similar history. E. coli is typically isolated in pure growth from the reproductive tract in these cases and disease is generally considered to be a result of ascending infection via the cloaca. Other factors such as intercurrent disease (as in the example of concurrent histomonosis above) as well as non-infectious factors can be involved, suggesting that salpingitis-peritonitis is often a result of opportunist infection. A recent paper (Olsen and others 2016) subdivided the gross pathological presentation into three types, namely type I comprising septicaemia-like lesions, type II comprising salpingitis, oophoritis, peritonitis and nephropathy, and type III in which there is salpingitis, oophoritis, peritonitis, nephropathy and septicaemia-like lesions, but there was no underlying bacteriological basis to this differentiation, and they may have represented different stages of infection associated with the same population of E. coli. Molecular studies showed that some outbreaks described in the study were caused by a clonal population structure of E. coli indicating a primary role of Avian pathogenic E. coli (APEC) rather than a secondary or opportunistic role. Molecular typing of the E. coli strains involved in outbreaks was considered important in order to distinguish primary APEC strains, which could be a potential target for vaccination, from opportunist strains which may be more amenable to other control measures. However a definitive ‘salpingitis’ strain type has not been established, and routine diagnostic molecular testing of E.coli is not yet available in GB.

Gizzard erosion in broiler and layer chickens

Erosion of the gizzard lining (ventriculitis) associated with fowl adenovirus (FAV) is well recognised in broiler chickens and may result in reduced weight gain accompanied by increased mortality. The lesions can be detected during post-mortem examination, with lesions in the koilin layer of the gizzard often accompanied by dark haemorrhagic gizzard contents. In recent cases investigated by APHA in 26-day-old broiler chickens, the demonstration of typical intranuclear inclusion bodies visible on histopathology of the gizzard lining has been consistent with adenovirus infection. The virus can be transmitted both horizontally from infected birds, and also vertically via the egg from infected parent flocks (Grafl and

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others 2012). However APHA has recently also investigated gizzard erosions in layer chickens, both adults and pullets in rear, with similar findings to those in broiler chickens including the presence of intranuclear inclusion bodies typical of adenovirus infection. Further investigation is being undertaken on the layer cases to confirm the involvement of adenovirus, as a potential new and emerging disease in the layer industry, and the potential effects of the disease on production. Control will rely ultimately on breaking the cycle of horizontal and vertical transmission.

UNUSUAL DIAGNOSES Poxvirus infection in backyard chickens SAC C VS confirmed the ‘wet’ (diphtheritic) form of poxvirus infection in a one-year-old female Sebright bantam which died after showing signs of poor appetite and respiratory distress. On gross post-mortem examination there was copious mucopurulent exudate in the sinuses, larynx and trachea which occluded the airway. On histological examination, there was marked subacute to chronic proliferative laryngitis and tracheitis with intracytoplasmic inclusion bodies consistent with those of poxvirus infection. This form of the disease is occasionally seen in backyard flocks and has the potential to cause asphyxiation. Infection occurs as a result of mechanical transmission of the virus to injured or damaged epithelium. The virus survives for long periods in dried scab material in the poultry environment and can also be transmitted by biting insects. The red mite (Dermanyssus gallinae) has also been implicated in transmission (Tripathy & Reed 2013).

HORIZON SCANNING

Histomonas meleagridis vaccination Turkey poults were vaccinated at one and 14 days of age with an attenuated strain of H. meleagridis. The birds were challenged with four field strains of H. meleagridis and the vaccinated birds were found to be protected against all four strains, indicating cross-protective capability of the tentative vaccine strain against heterologous virulent isolates (Sulejmanovic and others 2016). The results of this study were encouraging in attempts to seek potential control methods for histomonosis.

Astrovirus infection/white chicks

A ‘White chicks’ syndrome has been described in chicks in Europe and North America associated with Chicken astrovirus (CAstV) infection (Smyth and others 2013). In addition to white feathering in some affected chicks, the condition is also characterised by reduced hatchability, and weak chicks. A recent paper (Sajewicz-Krukowska and others 2016) has reported the condition in Poland. Affected chicks seen in a hatchery were the offspring of a parent flock aged 30 to 34 weeks, and up to 1% of chicks were affected. There was a 4-5% decrease in the ratio of hatched chicks to fertilised eggs. A CAstV was isolated from affected chicks, and the condition was reproduced experimentally when the virus was inoculated into embryonated eggs resulting in the hatching of white feathered chicks. The virus was transmitted horizontally to in-contact birds from the surviving inoculated chicks. The possibility of vertical transmission from the parent flock was suspected, although not proven. The potential impact of this disease will continue to be assessed.

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DIAGNOSTIC SUBMISSION TRENDS

The diagnostic submission trends for poultry in Q1-2016 for GB are shown in Figs. 7 and 8. These data include carcase and non-carcase (‘other’) submissions to both APHA (and its partners, indicated as 3PPP) and SAC V CS. There was an overall decrease in submissions compared with the same period in the prior two and five years. Figure 9 shows the trend for game bird submissions during the first quarter, which similarly shows a decline compared with recent years. In total there were 131 avian carcase submissions (excluding wild) received in Q1-2016 (compared with 155 in Q1-2015, a decline of 15%), and 230 avian non-carcase submissions (compared with 365 in Q1-2015, a decline of 37%). Comparison of the different chicken sectors shows differences between them (Fig 10); the number of layer and broiler (meat) submissions showing the least reduction for both carcase and non-carcase submissions compared with the previous two and five years, and there has been an increase in broiler breeder non-carcase submissions. Submissions of ‘pet’ (ie back yard and hobby) birds remain relatively low. The relative proportions of avian submissions in Q1-2016, both carcase and non-carcase, to APHA and its partners and to SAC C VS are shown in Fig. 11. The avian submissions for Q1-2016 include eight submissions from APHA’s partners, all of which were of poultry.

Diagnostic submission trends: comments

The trend over the last four years of declining carcase submissions to APHA and SAC C VS has continued this quarter. There are likely to be several reasons for this, including changed post-mortem provision arrangements by private veterinary practices and the changed footprint of APHA Surveillance Centres and other providers submitting diagnostic data for analysis by APHA which would have been a contributory factor since 2014 compared with previous years. The continued predominance of non-carcase submissions is likely to reflect both practitioners undertaking their own post-mortem examinations and also diagnostic field sampling, and the resulting use of relevant diagnostic tests available at APHA and SAC C VS. Avian diagnostic submissions data, trends and other information will continue to be monitored to assess their potential impact on scanning surveillance in GB and the detection of new and re-emerging threats. Figure 7: Poultry submissions (excluding game birds) in Q1-2016 in GB (Carcase and non-carcase) compared with the previous 2 years and previous 5 years to APHA and its partner providers (3PPP) and SAC C VS

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Figure 8: Poultry submissions (excluding game birds) in Q1-2016 in GB (Carcase and non-carcase) compared with the previous 2 years and previous 5 years; geographical basis

Figure 9: Game bird submissions in Q1-2016 in GB (carcase and non-carcase) compared with the previous 2 years and previous 5 years Figure 10: Submissions of chickens by sector in Q1-2016 compared with the previous 2 years and previous 5 years

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Figure 11: Avian diagnostic submissions to APHA and partners, and SAC C VS in Q1, 2012-2016

REFERENCES APHA (2014) GB Emerging Threats Report – Avian diseases, vol 18 no 4 (October-December 2014) https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/413630/pub-survrep-a0414.pdf [accessed 16 November 2015] APHA (2015) GB Emerging Threats Report – Avian diseases, vol 19 no 4 (October-December 2015) https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/507456/pub-survrep-a0415.pdf [accessed 16 May 2016] Gibbens, N., Brown, I.H, & Irvine, R.M., (2014).Testing for exclusion of notifiable avian disease. Veterinary Record, 174, 534-535

Grafl, B., Aigner, F., Liebhart, D., Marek, A., Prokofieva, I., Bachmeier, J. & Hess, M. (2012) Vertical

transmission and clinical signs in broiler breeders and broilers experiencing adenoviral gizzard erosion.

Avian Pathology 41, 599-604

Hess, M., Liebhart, D., Bilic, I. & Ganas, Petra (2015) Histomonas meleagridis – New insights into an old pathogen. Veterinary Parasitology 208, 67-76 Olsen, R.H., Bisgaard, M., Christensen, J.P., Kabell, S. & Christensen, H. (2016) Pathology and Molecular Characterisation of Escherichia Coli Associated with the Avian Salpingitis-Peritonitis Syndrome. Avian Diseases 60, 1-7 Sajewicz-Krukowska, J., Pać, K., Lisowska, A., Pikuła, A., Minta, Z. Króliczewska, B & Domańska-Blicharz, K. (2016) Astrovirus-induced “white chicks” condition – field observation, virus detection and preliminary characterization. Avian Pathology 45, 2-12

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Smyth, V., Trudgett, J., Wylie, M., Jewhurst, H., Conway, B., Welsh, M., Todd, D., Kaukonen, E. & Perko-Mäkelä, P. (2013) Chicken astrovirus detected in hatchability problems associated with ‘white chicks’. Veterinary Record 173, 403-404

Stokholm, N.M., Permin, A., Bisgaard, M. & Christensen, J.P. (2010). Causes of Mortality in Commercial

Organic Layers in Denmark. Avian Diseases 54, 1241-1250

Sulejmanovic, T., Bilic, I., Hess, M. & Liebhart, D. (2016) An in vitro attenuated strain of Histomonas

meleagridis provides cross-protective immunity in turkeys against heterologous virulent isolates. Avian

Pathology 45, 46-53

Tripathy, D.N. & Reed, W.M. (2013) Pox. In Diseases of Poultry, 13th Edition Ed. Swayne, D.E., Ames,

Iowa, USA; John Wiley & Sons, Inc, page 340.