Section 15 Poultry
- Laura Garza Cuartero
- Olwen Golden
- Ann Sharpe
- Central Veterinary Research Laboratory, DAFM, Backweston, Co. Kildare, Ireland
15.1 Avian Influenza Surveillance
Avian influenza type A is a contagious disease caused by viruses which are naturally found in, and adapted to, populations of wild birds. Avian influenza viruses can also affect poultry and mammalian species including rodents, pigs, cats, dogs, horses and humans.
Based on the severity of the disease, Avian Influenza is divided into low pathogenic (LPAI) and high pathogenic (HPAI) strains. LPAI may present with mild or no clinical signs in poultry. On the other hand, HPAI strains can cause severe clinical signs such as respiratory signs, reduced food intake, diarrhoea and nervous signs. In some cases, HPAI strains can cause sudden death with no other symptoms; in layers, drop in egg production and poor egg quality has been reported.
Avian Influenza viruses are classified into subtypes based on two surface proteins: haemagglutinin (HA) and neuraminidase (NA). H5 and H7 subtypes have been associated with acute clinical disease in chickens, turkeys and other birds of economic importance.
15.1.1 Active surveillance
DAFM carries out two types of active surveillance for avian influenza.
15.1.1.1 Serology testing in poultry for the national Poultry Health Programme (PHP)
The Poultry Health Programme is a DAFM surveillance programme supporting poultry trade and complying with EU regulations and ‘Council Directive 2009/158/EC of 30 November 2009 on animal health conditions governing intra-Community trade in, and imports from third countries of, poultry and hatching eggs’. PHP also includes testing for Mycoplasma and Salmonella arizonae. Last year, 13301 poultry species were tested through this programme (Table 15.1).
15.1.1.2 H5 and H7 serology testing of poultry under the EU Poultry Surveillance Scheme
Ireland uses the representative sampling method described in the Commission Implementing Decision 2010/367/EU of 25 June 2010 on the implementation by Member States of surveillance programmes for avian influenza in poultry and wild birds. In 2018, 10263 samples were tested for H5 and H7 HAI. Up to 2018, results have been reported to the European Commission; from 2019 onwards, results will be submitted to EFSA. Categories sampled for the EU Poultry Surveillance Scheme include:
- Broilers - Free Range
- Chicken Breeders
- Layers - Free Range
- Layers - Non-Free Range
- Fattening Turkeys
- Turkey Breeders
- Fattening Ducks
- Fattening Geese
Figure 15.1: Group of hens. Photo: Cosme Sánchez-Miguel
15.1.2 Passive surveillance
15.1.2.1 PCR testing of wild birds
Wild bird surveillance for avian influenza in Ireland is risk-based. It is implemented as a passive surveillance scheme; dead, moribund or sick birds are reported to DAFM by members of the public or the National Parks and Wildlife Service (NPWS) by ringing the Avian Influenza Hotline (076 1064403) or the after-hours number (1850 200456). Birds are collected by trained personnel and submitted to Regional Veterinary Laboratories (RVL) for sampling. Samples are then submitted to the Central Veterinary Research Laboratory (CVRL) where Avian Influenza testing is carried out. A list of species of wild birds to be targeted for surveillance for avian influenza is provided by the Commission Implementing Decision 2010/367/EU in accordance with the scientific opinion provided by EFSA. The list of wild birds to be targeted for AI surveillance (H5 HPAI) is amended according to the demographics of each country.
Until 2018, results of wild bird surveillance were submitted to the European Commission; from 2019 onwards, results will be submitted to EFSA. In 2018, 148 wild birds were tested. Of these, two white-tailed sea-eagles and one common buzzard were Avian influenza positive (H5N6), one mute swan was AI positive but not H5, H7, N1 or N8 (Table 15.1).
15.1.2.2 PCR testing of poultry
Avian influenza is a notifiable disease in Ireland, meaning that anyone who suspects that an animal may have the disease is legally obliged to notify DAFM. Poultry samples and carcasses are submitted routinely to RVLs and CVRL by private veterinary practitioners (PVPs) and backyard flocks owners for PCR testing for the purposes of diagnosis, screening and exports/imports. Farmers are encouraged to report suspect avian influenza cases to their local Regional Veterinary Office and to make use of their local Regional Veterinary Laboratory to aid with diagnosis of disease conditions. All data on Avian Influenza surveillance must be provided to the European Reference Laboratory (EURL) annually. Last year, 696 poultry birds were submitted and tested for AI PCR.
| Type | No. Animals | No. Positive |
|---|---|---|
| Poultry Health Programme (AGID test) | 13301 | 0 |
| H5 and H7-EU Surveillance (HI test) | 10263 | 0 |
| Poultry - PCR | 696 | 0 |
| Wild birds - PCR | 148 | 4* |
| * Three H5N6 and one non-HPAI |
15.2 Avian Mycoplasma Surveillance
15.2.1 Active surveillance
The Poultry Health Programme operated by DAFM includes surveillance for poultry mycoplasmosis. Mycoplasma spp. in poultry, whilst of no public health concern, can present significant problems, both commercially and, potentially, for bird welfare. Therefore, poultry are screened for Mycoplasma gallisepticum and/or Mycoplasma meleagridis.
-Mycoplasma gallisepticum (MG)This mycoplasma is associated with chronic respiratory disease. Typically, it is slow in onset and can result in significant commercial losses. This mycoplasma can infect chickens, turkeys and game birds. Ducks and geese can also become infected, particularly when associated with infected chickens. -Mycoplasma meleagridis (MM) With this mycoplasma vertical transmission through eggs can be a significant factor. It is a disease of breeding turkeys with clinical signs possible in progeny chicks. Respiratory symptoms are the main cause of economic loss.
DAFM Poultry Health Programme seeks to provide a surveillance platform for MG and MM. As part of this programme, breeding flocks are routinely tested for serological evidence of MG (turkeys and chickens) or MM (turkeys only). The plan for each poultry subgroup varies but, typically, flocks are subject to serological testing at pre-movement (from rearing), point of lay and during production (typically every 12 weeks).
Frequency of sampling is set out in the Council Directive 2009/158/EC of 30 November 2009 on animal health conditions governing intra-Community trade in, and imports from third countries of, poultry and hatching eggs, and the EU commission Decision 2011/214/EU. Sample size is based on a representative sampling strategy: 60 birds per house in houses of 1000 birds or more, with design prevalence of 5 per cent.
In 2018, 30620 and 1730 serum samples were screened for M. gallisepticum and M. meleagridis, respectively, at CVRL as part of DAFM official sampling (Table 15.2).
15.2.2 Passive surveillance
In addition to M. meleagridids and M. gallisepticum, M. synoviae is also tested as passive surveillance. In Ireland, these three serotypes are notifiable diseases, meaning that anyone who suspects an animal may have this disease is legally obliged to notify DAFM.
Beyond disease reporting, DAFM operates a network of RVLs, strategically located around the country. Farmers and PVPs are encouraged to report suspects to their local Regional Veterinary Office and to make use of their local RVL to aid with diagnosis of disease conditions.
| Submission type | Test | No. Tests | No. Positive |
|---|---|---|---|
| Poultry Health Program | M. gallisepticum SPAT | 30620 | 0 |
| Avian Influenza AGID | 13301 | 0 | |
| M. meleagridis SPAT | 1730 | 0 | |
| Salmonella arizonae H SAT | 1400 | 0 | |
| EU-H5 H7 HI-Surveillance | Avian Influenza H5 | 10263 | 0 |
| Avian Influenza H7 | 10263 | 0 |
15.3 Avian Salmonella surveillance
As part of the national Poultry Health Programme, serological testing for screening of Salmonella enterica subsp. arizonae is carried out in turkey flocks (Table 15.3). Last year, 1400 serum samples were screened for S. arizonae.
| Avian Production Type | No. Animals | No. Positive |
|---|---|---|
| Broiler Breeder | 826 | 0 |
| Layer | 413 | 0 |
| Broiler | 127 | 2* |
| Turkey Fattener | 58 | 13** |
| Broiler Grandparent | 42 | 0 |
| Turkey Breeder | 12 | 0 |
| Layer Breeder | 4 | 0 |
| * S. Braenderup and S. Kentuky; | ||
| † 11 cases of S. Derby in two sites and 2 of S. Senftenberg |
In parallel, every year, DAFM carries out the EU-Salmonella Surveillance by collecting samples on-farm and confirming detected serotypes by culture. Programme is as follows:
- In at least one flock of broilers on 10 per cent of commercial broiler premises with at least 5000 birds.
- Three times a year for all broiler breeder premises with at least 250 birds
- In at least one flock per year per layer holding comprising at least 1000 birds
- Once a year in one flock on 10 per cent of holdings with at least 500 fattening turkeys
- Once a year in all flocks on 10 per cent of holdings with at least 250 adult breeding turkeys between 30 and 45 weeks of age and all holdings with elite, great grandparents and grand-parent breeding turkeys.
In 2018, 1482 samples from farms were analysed; of these, 2 cases were detected in broiler breeder farms and 13 in turkey fattener flocks by culture (Table 15.2).
15.4 Newcastle Disease
Newcastle Disease is a notifiable disease that affects poultry, it is caused by virulent strains of Avian Avulavirus 1 -AAvV-1- (prior called Avian Paramixovirus type 1 -APMV1-). A similar variant, Pigeon AvV-1 (PPMV1) infects pigeons and other wild birds. AAvV-1 infections present a wide range of clinical signs depending of strain virulence; from lethargy and mild respiratory signs, to egg drop production, neurological signs and sudden death. Every year, samples from suspected cases and carcasses from poultry are submitted to CVRL and RVLs for ND testing. In addition, wild bird carcasses are screened by PMV1 as a means of passive surveillance. In 2018, a total of 74 wild birds and 209 poultry were tested; of these, 7 pigeons were positive (high virulent strain) as well as 2 sparrow hawks and 1 Black-Headed Gull; they were confirmed by PPMV1 PCR.
15.5 DISEASE DIAGNOSTICS
Beyond the active and passive surveillance of important notifiable diseases, DAFM carries out testing of other notifiable and non-notifiable diseases that have significant economic impact. Samples from suspect and healthy animals, the latter for monitoring purposes, are submitted directly to CVRL (Table 15.4) and carcasses of animals are submitted to RVLs (Tables 15.5 and 15.6, and Figure 15.2).
| Pathogen | No. Tests | No. Positive |
|---|---|---|
| Avian pneumovirus | 12 | 0 |
| Chlamidia psittaci* | 41 | 3 |
| Infectious Bronchitis* | 599 | 16 |
| Infectious largyngotracheitis* | 21 | 0 |
| Mycoplasma synoviae* | 621 | 128 |
| Mycoplasma gallisepticum* | 661 | 4 |
| * Notifiable diseases |
Last year, 3 birds were confirmed positive for C. psittaci, 16 for Infectious Bronchitis, 126 for M. synoviae and 4 for M. gallisepticum by PCR (Table 4). These diseases are notifiable and, when suspected, tissue samples or carcasses should be submitted to RVLs or CVRL. In addition, some agents such as C. psittaci have zoonotic potential (see textbox).
C. psittaci
Psittacosis in humans is caused by Chlamydia psittaci, an obligate intracellular Gram-negative bacterium whose natural reservoirs are bird pets, wild birds and poultry species (pigeons, turkeys, ducks). Psittacosis has worldwide distribution and infection in humans occurs by inhalation of aerosols or direct contact with respiratory secretions or faeces of infected birds.
In humans, symptoms include flu-like symptoms such as fever, headache, and cough. Complications have been described such as pneumonia, endocarditis, hepatitis, arthritis, keratoconjunctivits and encephalitis. In humans disease can be controlled by using of antibiotics. Incubation period varies from 1–30 days; however, spread among humans is rare. In suspect human cases, local GPs and HSE should be contacted for advice.
In birds, symptoms can vary from unapparent to sudden death. It typically causes respiratory and/or liver problems or gastrointestinal symptoms, depending on species, age of birds and virulence of bacterial strain. In some cases, disease is carried by birds in a latent state, while still shedding bacteria, and then re-activated under immunosuppression or stressful conditions. When handling infected birds, high biosafety measures should be used such as gloves, protective eyewear and fitted respiratory mask.
In 2018, the most common diagnosis in poultry carcasses was enteritis (23 cases) followed by bacteraemia-septicemia, arthritis and blackhead (Table 5). In wild birds, however, poisoning and PPMV1 infection were the most common diagnosis (Table 6). In a number of carcasses the cause of death was not determined.
| Diagnosis | Count |
|---|---|
| Enteritis | 23 |
| No Diagnosis | 19 |
| Bacteraemia-septicaemia | 18 |
| Arthritis | 15 |
| Blackhead | 7 |
| Egg peritonitis | 7 |
| Pneumonia | 6 |
| Pericarditis | 6 |
| Marek’s Disease | 6 |
| Parasitic Gastro-enteritis | 5 |
| Sinusitis | 5 |
| Myopathy | 4 |
| Trauma | 3 |
| Air sacculitis | 3 |
| Fatty liver | 3 |
| Fatty liver haemorrhagic syndrome of layers | 3 |
| TB (M. Avium) | 2 |
| Cellulitis | 2 |
| Intestinal obstruction | 2 |
| Parasitic Bronchitis | 2 |
| Tumour | 2 |
| Impactations of crop, gizzard or duodenum | 2 |
| Poisoning | 1 |
| Cardiac tamponade | 1 |
| Abscessation | 1 |
| Anaemia | 1 |
| Bronchitis | 1 |
| Dermatitis | 1 |
| Encephalitis | 1 |
| Heart failure | 1 |
| Impaction-prolapse of the oviduct | 1 |
| Intussusception | 1 |
| Nephritis | 1 |
Figure 15.2: Diagnoses recorded in poultry post-mortem examinations
| Diagnosis | Count |
|---|---|
| No Diagnosis | 39 |
| Poisoning | 18 |
| PPMV-1 | 10 |
| Trauma | 6 |
| Parasitic gastro-enteritis | 3 |
| Avian Influenza | 3 |
| Amyloidosis | 2 |
| Malnutrition | 2 |
| Peritonitis | 2 |
| Bacteraemia-septicaemia | 2 |
| TB (M. Avium) | 2 |
| Cardiac tamponade | 1 |
| Enteritis | 1 |
| Oesophagitis | 1 |
| Arthritis | 1 |
| Pneumonia | 1 |
| Psittacosis | 1 |
| Fungal infection | 1 |
| Megabacteriosis | 1 |
15.6 Case reports in poultry
15.6.1 Tetratrichomonas gallinarum
Tetratrichomonas gallinarum infection was suspected in liver samples submitted from a 10 week old red legged partridge reared for game. Losses were low at about 10 birds/10000 birds. Caecal casts were noted on post-mortem examination. Multifocal lymphohistiocytic hepatitis was observed. Presence of trichomonads, which include T gallinarum, was confirmed using in situ hybridization. Liebhart et al. (2014) reported T. gallinarum infection in a flock of 2500 red-legged partridges in United Kingdom and characterised by sudden death of 15 birds within 2 days; circulation of a virulent strain of T. gallinarum in reared red-legged partridges was demonstrated. It is thought that infection is by contaminated food and could be associated with unsanitary feeding places (Amin et al. 2014).
15.6.2 Gallibacterium anatis
G anatis is a normal inhabitant of the upper respiratory tract and lower reproductive tract of chickens but is also considered to be a cause of salpingitis and peritonitis in laying hens (Deplazes et al. 2016). Salpingitis due to Gallibacterium anatis was diagnosed in an eight month old backyard hen, from a flock of 50 where fifteen hens had died over a 2 month period. This hen also had hepatic amyloidosis (most likely secondary to chronic systemic inflammation), colisepticaemia and granulomatous typhlitis due to presence of invasive trichomonad protozoa. Ascending infection from cloaca is suspected.
15.6.3 Enterococcus caecorum
Over the past 15 years, pathogenic strains of E. caecorum have become a significant cause of morbidity and mortality in broiler breeders. Repeated outbreaks occur. An environmental reservoir for pathogenic E. caecorum has yet to be identified (Jung et al. 2018). An outbreak of Enterococcus caecorum infection in 21 day old broilers was diagnosed. Birds presented with splayed legs and lameness, resulting in excess culling. They responded to antibiotics but when antibiotic administration ceased the problem returned. In some birds, the neck of the femur fractured easily on disarticulation. E. caecorum was cultured from pericardium, bone and joint. Affected birds had pyogranulomatous epicarditis, arthritis, tenosynovitis, osteomyelitis and chondritis.
15.6.4 Chronic cholera
Fowl cholera is more likely to occur in birds that are stressed by e.g. parasitism, poor hygiene, malnutrition and other diseases. Chronic cholera was diagnosed in 62 week old free range layers which were wasting and experiencing ongoing mortality. One bird, which presented with opisthotonus and twitching, had pyogranulomatous and fibrinous osteomyelitis at the base of the skull with adjacent cellulitis. Another bird had severe peritonitis and oophoritis with inspissated pus in ovaries. Pasteurella multocida was cultured from ovary, oviduct, liver and abdomen. A predisposing cause was not found in this outbreak.
15.6.5 Ornithobacterium rhinotracheale
Ornithobacterium rhinotracheale (ORT) is of worldwide distribution in commercial poultry, in which it is associated with respiratory diseases, and is also found in wild birds. Airsacculitis and pneumonia are the most common features of infection with ORT. Infection can be transmitted horizontally by aerosol and vertically through eggs, which probably accounts for its rapid and worldwide spread (Empel and Hafez 1999). ORT was isolated from a 36 day old organic broiler from a group which had Marek’s disease. This bird had cheese like material in its air sac. Other infections in the birds examined, which were likely due to virus induced immunosuppression, included coccidiosis, cryptosporidiosis and Gallibacterium anatis associated pneumonia.
References
Liebhart, D., S. Neale, C. Garcia-Rueda, A. M. Wood, I. Bilic, P. Wernsdorf, B. Jaskulska, and M. Hess. 2014. “A Single Strain of Tetratrichomonas Gallinarum Causes Fatal Typhlohepatitis in Red-Legged Partridges (Alectoris Rufa) to Be Distinguished from Histomonosis.” Avian Pathology 43 (5). Taylor & Francis: 473–80. doi:10.1080/03079457.2014.959435.
Amin, Aziza, Ivana Bilic, Dieter Liebhart, and Michael Hess. 2014. “Trichomonads in Birds – a Review.” Parasitology 141 (6). Cambridge University Press: 733–47. doi:10.1017/S0031182013002096.
Deplazes, Peter, Johannes Eckert, Alexander Mathis, G von Samson-Himmelstjern, and Horst Zahner. 2016. Parasitology in Veterinary Medicine. Wageningen Academic Publishers.
Jung, Arne, Laura R. Chen, M. Mitsu Suyemoto, H. John Barnes, and Luke B. Borst. 2018. “A Review of Enterococcus Cecorum Infection in Poultry.” Avian Diseases 62 (3): 261–71. doi:10.1637/11825-030618-Review.1.
Empel, P. C. M. van, and H. M. Hafez. 1999. “Ornithobacterium Rhinotracheale: A Review.” Avian Pathology 28 (3). Taylor & Francis: 217–27. doi:10.1080/03079459994704.
A cooperative effort between the VLS and the SAT Section of the DAFM