In an alarming discovery, the Michigan Department of Natural Resources (DNR) has confirmed that three red fox cubs from three separate dens in Lapeer, Macomb and St. Clair counties – from April 1-14 – died of complications associated with the Avian Flu. This is Michigan’s first confirmation of highly pathogenic avian influenza (HPAI) in wild mammals.
According to the agency, DNR officials had been contacted by a professional wildlife rehabilitation specialist located in southeast Michigan about the pups, which had neurological symptoms associated with HPAI prior to their deaths, including tremors, convulsions, and a process known as spinning in circles. Two of the three puppies died shortly after being seen by the specialist, and the third died after showing signs of recovery. Agency officials later explained that a fourth animal, a sibling of the Macomb County pup, survived the virus. However, the condition caused the pup to lose his sight and rendered him unfit for release into the wild. The female pup will be cared for by staff at a local nature center.
Sampling of the three deceased pups was done in-state by the DNR Wildlife Disease Lab and then forwarded to the Michigan State University Veterinary Diagnostic Laboratory for testing and evaluation. All three returned “non-negative” results, as of May 6; however, all three tested “positive” when examined at the National Veterinary Services Laboratory in Ames, Iowa on May 11. Swabs taken during the examination revealed the presence of the virus. After the tests, the researchers performed necropsies on each of the three puppies in an effort to better understand how HPAI progresses in mammals.
Michigan is not the first state to confirm the presence of the HPAI virus in red foxes. According to literature from a rehabilitation center in the Netherlands and reported in the scientific journal, Emerging infectious diseases, the H5N1 virus, a form of HPAI, was detected in red fox cubs during a viral outbreak among wild bird populations in May 2021. A year later, on May 2, 2022, a pair of red fox cubs was found to carry the virus; one was found deceased and the other died shortly thereafter and after exhibiting neurological symptoms consistent with HPAI. Also on May 11, at the same time Michigan puppies were confirmed, a red fox pup from Anoka County, Minnesota was confirmed to have HPAI, making it the state’s first positive test. in a population of wild mammals.
Read more: Bird flu detected in Florida — Fourth US state in current outbreak
“HPAI/H5N1 viruses can sometimes transfer from birds to mammals, as has happened in these cases,” says Megan Moriarty, wildlife veterinarian at Michigan DNR. “And there may be additional detections in other mammals during this outbreak, but these will likely be isolated cases. At this stage, it is not known how the fox (cubs) became infected, but it it is possible that he was exposed by consuming infected birds, such as waterfowl.
Scientists believe HPAI originated in wild bird populations, particularly waterfowl such as ducks and geese. The disease has been confirmed in domestic poultry facilities in 34 states to date, with 35 states also having confirmed the virus in wild bird populations. Highly contagious, particularly to domestic poultry, HPAI also affects raptors such as eagles, hawks and vultures.
Anyone observing birds or animals with what appear to be neurological problems – encirclement; tremors; seizures; drooping head/neck or wings; or general uncoordinated or seemingly unnatural movements or movements – should contact their local DNR office or state Department of Health.
