Backyard poultry flocks in Finland: an infection risk to commercial poultry or humans?

Leena Katariina Pohjola

Tutkimustuotos: OpinnäyteVäitöskirjaArtikkelikokoelma


There is an increasing interest in keeping backyard poultry in many countries, including Finland. However, several studies in Western Europe and North America have identified the involvement of backyard poultry flocks in avian influenza virus outbreaks occurring in commercial poultry. In addition, commonly without any signs of illness, poultry can be carriers of enteric bacterial agents that are human pathogens. Farm management and biosecurity practices among 178 backyard poultry flocks were investigated using a questionnaire. Furthermore, the main causes of mortality of backyard chickens were studied through a retrospective study of necropsy data from the Finnish Food Safety Authority Evira from 2000 to 2011. In addition, voluntary backyard poultry farms were visited during October 2012 and January 2013, and blood samples, individual cloacal samples as well as environmental boot sock samples were collected from 51 farms and 457 chickens. The results of the questionnaire study revealed that the backyard poultry farms in Finland were mainly small (91 % ≤ 50 birds) and most flocks (98 %) had access to outdoors. Biosecurity practices, such as hand washing and changing shoes after bird contact were rare, 35 % and 13 % respectively. The farms were mainly located distantly (94 % > 3 km) from commercial poultry farms. The subjectively reported flock health was good (96 %). The most common postmortem diagnosis were Marek s disease (27 %) and colibacillosis (17 %). Of the zoonotic bacterial pathogens, Campylobacter jejuni and Listeria monocytogenes were frequently detected on the farms, 45 % and 33 %, respectively. Yersinia enterocolitica was also often isolated on the farms (31 %); however, all isolates were yadA negative, i.e. non-pathogenic. C. coli, Y. pseudotuberculosis and Salmonella enterica were rarely detected (2 %). All enteric bacteria were highly susceptible to most of the antimicrobials studied and only few AmpC- and no ESBL-producing E. coli were found. Avian encephalomyelitis virus, chicken infectious anemia virus and infectious bronchitis virus (IBV) antibodies were commonly found from the studied flocks, 86 %, 86 % and 47 %, respectively. The IBV detected from backyard poultry flocks were QX-type IBV strains differing from the strains found from commercial farms, suggesting different routes of infection for commercial and backyard poultry. The results indicated that among backyard poultry flocks pathogens circulate posing a risk to transmit infection to commercial poultry in Finland, but because of the distant locations and small flock sizes, the risk is relatively small. Notifiable avian diseases that also are of zoonotic potential (AIV and NDV) are very rare. Backyard chickens are a reservoir of C. jejuni strains and thus a potential source of C. jejuni infection for humans. Because of the lack of good hygiene after bird contact, the risk of transmission of the pathogen from birds to humans exists
Myöntävä instituutio
  • Helsingin yliopisto
  • Fredriksson-Ahomaa, Maria, Valvoja
  • Hänninen, Marja-Liisa, Valvoja
  • Huovilainen, Anita, Valvoja, Ulkoinen henkilö
Myöntöpäivämäärä7 huhtikuuta 2017
Painoksen ISBN978-951-51-3054-9
Sähköinen ISBN978-951-51-3055-6
TilaJulkaistu - 7 huhtikuuta 2017
OKM-julkaisutyyppiG5 Tohtorinväitöskirja (artikkeli)


  • 413 Eläinlääketiede

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