Can wild birds carry avian influenza?
Avian influenza circulates naturally in populations of waterbirds. A range of evidence suggests that wild birds can introduce low pathogenic H5 and H7 viruses to poultry flocks, which can then mutate to the highly pathogenic form. Under some circumstances HPAIs can then infect wild bird populations – contact between poultry and wild birds facilitates this exchange. Asian lineage HPAI H5N1 seems typically to cause high rates of mortality when it occurs in wild birds, but a study in SE Asia has shown that apparently healthy wild birds can carry the disease and shed viral particles – this is termed asymptomatic infection.
