Microbiological Hazards of Wild Birds and Free-Range Chickens

Abstract

Zoonotic diseases are those that can be transmitted to people from animals. Back yard chickens are a reservoir of multiple zoonotic agents that can be transmitted to people directly through bird handling, eating meat or eggs, or indirectly by infecting pets that can then bring the pathogens into the home and put them in contact with other members of the family. Wild birds do also carry zoonotic pathogens that can infect us directly or indirectly by first infecting our back yard chickens, pets or other livestock such as pigs. With the increase in hobby-back yard chicken farms and wild bird fanciers it is important for the public to understand the risks associated with this practices. In this chapter we review the microbiological hazards of wild birds and back yard chickens to human health. From well known enteric pathogens such as Salmonella to vector borne viruses, this chapter hopes to reflect the microbiological risks of keeping chickens and being in contact with wild birds as a hobby or business. Wild birds and domestic poultry can transmit viral diseases to people. In fact, waterfowl have long been considered the natural reservoirs of Influenza A viruses (IAV). The large population of these natural reservoirs and the ability of IAV to undergo genetic mutations and reassortment make Influenza A a noneradicable zoonosis. Wild birds are also the natural reservoirs of Newcastle disease viruses (NDV) which can transmit to domestic poultry and cause outbreaks of high mortality after infection with virulent strains. Humans can become infected with these viruses after direct contact with infected birds and usually develop a self-limiting conjunctivitis.