Rabies vaccine bait is being spread throughout Allegheny County over the next five weeks as part of an annual effort to prevent the raccoon strain of the infectious disease from spreading further west.
To entice raccoons, vaccine doses are encased in either fishmeal or a waxy vanilla substance. The veterinary drug is then tossed from helicopters over less populated areas or scattered by hand down storm drains, in abandoned yards and under dumpsters.
Finding spots where raccoons will find the treats, but humans and pets won’t, can be challenging, said the Allegheny County Health Department’s Jamie Sokol, who coordinates the baiting program.
“It takes a good deal of thought and effort. But we get it done, and we hit pretty much the entire county, top to bottom,” Sokol said.
The county undertakes this arduous work in collaboration with the U.S. Dept. of Agriculture’s Wildlife Services, which is in its 22nd year. Recently the program had some success.
A new vaccine from a Canadian manufacturer was used last year; since then, there’s been a significant drop in the number of raccoons testing positive for the virus. Just two raccoons in Allegheny County have turned up positive in 2023, said USDA wildlife biologist Amy Hess; there were 16 in 2021 and eight in 2022. Hess noted that all of the positives from last year were identified before the new bait was distributed last summer.
“We do know that rabies is cyclical, and we might see a little bit of a wave. But we’ve never seen it be this low,” said Hess, who has been working for the USDA to combat rabies in Pennsylvania since 2003. “That’s pretty exciting.”
The annual U.S. economic burden for rabies exceeds $500 million, said Centers for Disease Control and Prevention microbiologist Rene Edgar Condori during an appearance on a podcast produced by the federal agency. The figure includes the costs of testing animals for the virus as well as post-exposure prophylaxis treatment for up to 60,000 Americans every year.
The rabies virus can infect any mammal, though one of the main strains exists in raccoons. These omnivores are opportunistic feeders that make meals from trash or food left for feral cat colonies. In urban and suburban settings, raccoon populations are dense enough that the virus can spread to new hosts before the infected animal dies from the disease that attacks the central nervous system.
Stopping the spread westward
Pittsburgh is the westernmost city where the raccoon rabies strain is found. Vaccination efforts here are financial and public health investments as it creates a boundary of immune animals, explained Penn State’s Justin Brown, an assistant teaching professor in the Department of Veterinary and Biomedical Sciences.
“Raccoons are the reservoir, what keeps the virus in nature,” said Brown, who explains that because of rabies circulating among raccoons, it can spill over to other wildlife such as skunks, bear, even deer, as well as livestock, domestic animals and sometimes humans.
Hess and Sokol hope that rabies will eventually be eradicated from the Allegheny County raccoons; they want to push the boundary of infected animals eastward. That may not be possible, said Brown, but that doesn’t make efforts here unsuccessful.
“If we can keep it less prevalent in the raccoon wildlife population then that will have success and positive benefits,” said Brown.