A wild mallard duck found near a state wildlife refuge in Fairbanks, Alaska has tested positive for the H5N2 form of avian influenza
. The positive test was confirmed in a recent announcement
by the United States Department of Agriculture’s (USDA) Animal and Plant Health Inspection Service (APHIS), making this the first appearance of the influenza strain in a wild or commercial bird in the country in over a year.
In 2015, the H5N2 virus made its way through Midwestern poultry farms, killing nearly 50 million domestic or captive chickens, turkeys, and other birds in 15 states. That outbreak triggered an 80% spike in egg prices and massive economic losses for US poultry farmers. From July 2015 through June 2016, the USDA has worked with state and local officials to monitor and test wild birds for avian influenza. During that surveillance, researchers collected more than 45,000 test samples from wild birds in an effort to detect the virus and prevent it from spreading to commercial poultry flocks. Since July 2016, the surveillance has included about 4,000 new samples and the USDA plans to collect about 30,000 more by July 2017.
Wild aquatic birds such as ducks, geese, and swans from around the world naturally carry H5 avian influenza viruses in their intestinal and respiratory systems, often without getting sick. Avian influenza viruses are highly contagious between birds, and can spread quickly through commercial flocks that come in contact with the saliva, nasal secretions, and feces of infected wild migratory foul. Low pathogenic avian influenza (LPAI) viruses may cause little to no illness in poultry and can cause reduced egg production in hens. The deadlier high pathogenic avian influenza (HPAI) viruses, such as the one that plagued American egg farmers last year, can decimate previously healthy flocks.
Around the world, human cases of avian influenza are rare, and there have been no bird-to-human H5 infections in the United States to date. According to the World Health Organization
, since 2003 the H5N1 form of avian influenza has infected 850 people primarily in Africa and Asia, resulting in 450 deaths. The zoonotic forms of the virus that can be transmitted from birds to humans can present in both LPAI or HPAI forms. In people, symptoms of avian influenza include conjunctivitis, fever, cough, sore throat, and pneumonia, with more serious illnesses potentially leading to respiratory failure and death. People who come in contact with any wild birds or domestic poultry may be exposed to the virus if any of the bird’s saliva, feces, or mucous gets into their nose, eyes, or mouth.
While the Centers for Disease Control and Prevention assert that avian influenza poses a very low health risk to humans, they urge precaution for anyone who may come in contact with wild or domestic birds. “Since wild birds can be infected with these viruses without appearing sick, people should minimize direct contact with wild birds by using gloves,” the USDA warned in its press release. “If contact occurs, wash your hands with soap and water and change clothing before having any contact with healthy domestic poultry and birds. Hunters should dress game birds in the field whenever possible and practice good biosecurity to prevent any potential disease spread.”
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