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Why nearly 40,000 caramel-scented rabies vaccines landed around Burlington last week

Peter Hirschfeld
Colchester Point photographed from above in 2016.

Last Friday, Owen Montgomery spent the day in a helicopter, flying over Burlington and surrounding towns and dropping more than 30,000 packets of frozen rabies vaccines.

The U.S. Department of Agriculture Wildlife Services program that Montgomery works with does this every summer to try to manage rabies in raccoons, skunks and foxes across the state. But this is the first year in over two decades there’s been an extra vaccine drop in Vermont. That’s because of a localized rabies outbreak in Chittenden County wildlife.

“It all started in March of 2021 in Williston, there was a skunk at a housing development,” Montgomery said. Since then, about two dozen raccoons, skunks, and foxes have tested positive for rabies in the greater Burlington area. Before that, there hadn’t been a rabies case outside a bat in the region in years.

“There were several weeks last year where we would just always get a positive,” said Dr. Natalie Kwit, a veterinarian at the Vermont Department of Health. “It was kind of like, ‘Oh no, here’s another.’”

It’s not clear why the rabies virus has taken off in wildlife around Burlington — the population of raccoons and skunks around the city has grown in recent years, and the mandatory composting law could be providing the animals with a steady food source.

So far, Kwit said there hasn’t been evidence that people or pets in the region are getting exposed to rabies more often. But that’s the concern, and why the federal agency green-lit a plan to spread nearly 40,000 packets of rabies vaccines from Milton to South Burlington by helicopter, vehicle, and hand last week for wildlife to find.

The bait is small and pungent. They’re covered with a sticky brown coating to attract animals. “This one actually smells pretty lovely,” Kwit said. “It smells like a Nilla wafer.”

Inside is a pressurized packet filled with liquid vaccine. When an animal bites into it, it squirts in their mouth.

"It's a live adenovirus vaccine that triggers the antibody response in the animal," Montgomery explained. The vaccine becomes inactive very quickly in the environment.

He emphasized there are not environmental or public health hazards to the vaccines. "This has been tested and tested and tested a long time," he said. "If it wasn't safe for the environment, then trust me, they wouldn't let us do it."

Not all of the vaccines get to their intended targets. Squirrels take them, and so do possums and feral cats. “There are trees that have got to be full of these baits in the city,” Montgomery said.

He estimates about 20% of the packets he drops will reach the raccoons, skunks and foxes he wants to inoculate.

“The reason for putting that amount of density of baits on the landscape is to afford an opportunity to all of our target animals to possibly find one and uptake the bait.”

He's getting ready to do the whole thing again in August.

For the Vermont USDA Rabies Hotline, call 1-800-4-RABIES (1-800-472-2437) or 1-802-223-8690.

Have questions, comments or tips? Send us a message or reach out to reporter Lexi Krupp:


Lexi covers science and health stories for Vermont Public.
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