Avian Influenza Virus (AIV) infections occur naturally in wild bird population and can cross the wildlife-domestic line. Since the 2015 Highly Pathogenic Avian Influenza (HPAI) outbreak occurred despite the use of strict biosecurity controls, it is suggested that an alternative route of the virus may have existed or currently exists.
The objective of this research is to determine whether small terrestrial wild birds (e.g., sparrows, starlings, and finches), rodents, and/or insects can transmit avian influenza viruses, including H5N2, between traditional wildlife reservoirs (i.e., waterfowls/shorebirds) and commercial layer operations, or among such farms.
The information will help in developing targeted mitigation strategies for the poultry industry based upon which species (and which locations) are most likely to contribute to AIV transmission. Such actions may include recommending avicides to be used near off-site feed mills or non-poultry CAFO’s, augmenting rodent and insect control, and replacing biobarriers (trees, shrubs) with inorganic materials (walls, fencing) to protect poultry operations against AIV transmission from wild birds.
Iowa State University scientists who worked on this project included: Dr. Kyoung-Jin Yoon, professor in the Department of Veterinary Diagnostic and Production Animal Medicine, Dr. James S. Adelman, assistant professor in the Department of Natural Resource Ecology and Management, Dr. Yuko Sato, assistant professor and extension poultry veterinarian for the state of Iowa and Julie Blanchong, associate professor with the Department of Natural Resource Ecology and Management.
This project included sampling 554 small birds (i.e., songbirds, woodpeckers, etc.) and rodents found at four Iowa wetlands. Three wetlands were located within six miles of farms that where positive for HPAI. Swabs, both internal and external, were collected during spring migration and tested by Polymerase Chain Reaction (PCR) and virus isolation tests.
None of the internal (oropharyngeal and cloacal/rectal) and external (feather/fur and feet) swab samples tested positive for AIV. Blood samples also did not show any antibodies against influenza A virus. It can then be concluded that it is unlikely that small wild birds and rodents are major factors in the transmission and spread of AIV.
Future research should be focused on other alternative routes of AIV transmission. Examples of such routes could be human-mediated transfer, aerosolized particulates, and/or contaminated food/water.