|Carrie Robbins, DVM Candidate|
"I worked with Dr. Pat Redig (TRC) and Dr. Carol Cardona (Ben Pomeroy Chair in Avian Medicine, VBS) to study Newcastle virus exposure in raptors and waterfowl. This study is very relevant because as of late July this year there was an outbreak among cormorants, pelicans and gulls in several Minnesota lakes that has killed thousands of birds. Newcastle virus has been studied extensively in poultry, where it can cause quite devastating outbreaks, but little is known about how it is transmitted among wild birds. There have been large Newcastle related die-offs among waterfowl in Minnesota since the 1990’s, most recently in 2008, 2010 and 2012. We know that Newcastle virus can cause severe neurological disease in juvenile cormorants and pelicans, whereas raptors generally have subclinical infections. Fortunately, Newcastle virus is only known to cause mild conjunctivitis is humans, but it is in the same family (Paramyxoviridae) as some very scary viruses, including Measles virus, Mumps virus, Canine distemper virus and Nipah virus.
Dr. Redig and I wanted to investigate why these deadly outbreaks are occurring every two years in waterfowl and test whether the occurrence of Newcastle virus antibodies in raptors corresponded with known outbreaks. I worked with Dr. Cardona’s lab to test 422 plasma samples from bald eagles, great horned owls, peregrine falcons and red-tailed hawks that were archived at TRC from 2008 through present. I hypothesized that raptors who feed on waterfowl (eagles, horned owls and peregrine falcons) would be at higher risk for Newcastle virus exposure than rodent-eating birds (red-tails). Indeed, 5% of horned owls and eagles had antibodies to Newcastle virus, indicating that they were exposed to the virus and mounted an immune response. These birds were brought to TRC for other injuries and illnesses, so we do not know whether they had clinical symptoms caused by Newcastle virus. When we looked at the seropositive birds (e.g. tested positive for antibodies) over time, we did not find a correlation with known outbreaks among waterfowl. Thus, Newcastle virus appears to persist in the environment outside of reported outbreaks and certain species (eagles and horned owls) may be more susceptible to exposure based on their diet or habitat preferences."