High-Flying Trick-Or-Treat Delivers Rabies Vaccines For Raccoons

JOHN DANKOSKY: This is Science Friday. I’m John Dankosky. Rabies is one of the deadliest diseases in the world. It’s fatal in a whopping 99% of cases. And because of that, rabies prevention has been one of the most important public health initiatives in the US.

From August to October each year, the USDA leads a mass vaccination effort to try to keep the disease from being carried by critters, an action-packed adventure involving raccoons, helicopters, and fish-flavored candy. Yes. Here to tell us more is my next guest. Jordona Kirby is the rabies field coordinator for the USDA’s National Rabies Management Program. Jordona, welcome to Science Friday. Thanks so much for joining us.

JORDONA KIRBY: Thank you, John. I really appreciate the opportunity to talk about our program today.

JOHN DANKOSKY: So before we get into the details of the program, give us a sense of just how big a deal rabies in the US is right now.

JORDONA KIRBY: So one thing I think that probably most people are not aware of in the United States is that rabies is still very much an issue when it comes to public health and wildlife management. More than 90% of 5,000 to 7,000 rabies cases that are reported annually in our country occur in wild animals. And specifically, raccoons are one of the most common species confirmed with the disease.

This presents a challenge because raccoons are highly adaptable. They are found just about everywhere in the US. They’re very ubiquitous, and they’re extremely charismatic. So they thrive in most environments throughout our country. In areas where both raccoon and bat rabies circulates, human rabies exposures are actually 600% higher as compared to areas where there’s only bat rabies.

JOHN DANKOSKY: So pretty much anywhere you can find raccoons in the United States, you are likely to find rabies.

JORDONA KIRBY: Not necessarily. So raccoon rabies specifically, where raccoons serve as the primary reservoir for the disease, is only found in the eastern United States. And so throughout the rest of the country, there are other reservoirs or other species that are more likely to carry rabies. And those include bats throughout the entire country, as well as pocket areas where skunks are the primary reservoir and most likely to spread the disease, or in some cases foxes or coyotes.

JOHN DANKOSKY: So you’re in your field season right now. Maybe you can walk us through how exactly the USDA vaccinates for rabies.

JORDONA KIRBY: Our program was started in the 1990s. And the scope of the program targets wildlife rabies prevention specifically. The immediate objective of our program is to prevent raccoon rabies from spreading any further north into Canada or west beyond its current extent in coastal Alabama. And the primary way that we do that is to orally vaccinate raccoons and other target species using an oral vaccine or an ORV bait and distributing those at a landscape scale. And we typically distribute a majority of those baits using low-flying airplanes, along with helicopters and vehicles.

JOHN DANKOSKY: You’re dropping some sort of baited vaccination for raccoons to just pick up from the ground? I mean, how does this work? It sounds like a massive undertaking, first of all.

JORDONA KIRBY: Yes, it is. It’s quite an undertaking. It really does involve a year-long planning process. But we use the latest in science, data, and technology to plan out where we’re actually going to distribute these ORV baits. And so by doing that, it gives us the ability to truly target very specific areas. And using airplanes at a landscape scale really is the most efficient and effective way to get a majority of these baits out on the ground.

We start in Maine beginning in August, and we finish up in the north to north central part of Alabama by the end of October. And during that time, we put out about 75% or more of the total baits that are distributed on an annual basis.

JOHN DANKOSKY: Are these baits then being dropped sort of across a large landscape? Are they being targeted in places where we know there are going to be more raccoons? Give us a sense of exactly where these might be falling from an airplane.

JORDONA KIRBY: Sure. So we very strategically decide where to place the ORV zones. And we do that by looking at the surveillance data for the disease itself. We’re establishing about a 25-mile-wide barrier. And within that barrier, we’ll drop the ORV bait packets, thereby creating kind of this vaccination zone. And then there’s the barrier– excuse me– between vaccinated and unvaccinated individuals.

In these areas, we typically don’t see a lot of cases of rabies because we’ve been able to locally eliminate it and prevent the spread. So we do see a decline in cases through time as we continue to vaccinate in these specific areas. So we are currently preventing the spread and preventing it from traveling any further than where we currently find it. But eventually, we’d like to shift our ORV zone back to the east and eliminate it. It’s something that over a 50- to 80-year horizon, if you can imagine, is our long-term vision.

JOHN DANKOSKY: So getting back to these packets, these vaccination packets that are dropped from airplanes or helicopters, describe what they look like. What do they taste like? Why are they so attractive to raccoons?

JORDONA KIRBY: We have two different attractants, if you will, and two different bait types that we’re currently using. So the first bait type– it’s called Raboral V-RG, and it is the only licensed product that we currently can use specifically targeting wildlife today in the US. That bait looks almost like a small ketchup packet, if you will. It’s a small, rectangular sachet containing the liquid vaccine. And it’s coated in wax along with a very pungent, fish-based oil. And then that oil is coated with fish crumbles.

And then the other bait type that we’re using is called ONRAB. That bait is still considered an experimental vaccine in the United States, although it has been licensed for use in Canada. And that bait’s a little different in that it is actually a sweet, vanilla-based coating. It works equally as well in terms of attractiveness to raccoons and other animals. It just is a little bit different in terms of the appearance of the bait and the attractant on the bait itself.

JOHN DANKOSKY: I can only imagine that a lot of our listeners probably either have a dog or a cat or know a dog or a cat who, if they came across something that was vanilla flavored or probably even better yet fish flavored, they’d probably gobble it up right away. I mean, is this stuff safe for household pets or other animals?

JORDONA KIRBY: It is safe. Yes, absolutely, although it is not licensed for use in domestic animals. That is actually a question we get all the time– hey, can I get one of these baits to vaccinate my dog instead of taking them in for their annual shots? And unfortunately, the answer to that is no.

The baits are safe. And although it’s not common, it is possible that dogs, in particular, are potentially likely to encounter any of our baits on the landscape. We do our best to try to prevent that from happening. When our employees are flying in the planes as well as in the helicopters, they have the ability to turn the baiting equipment on and off. And they do that very specifically in areas where we’re trying to avoid pets and people from finding the baits themselves.

JOHN DANKOSKY: Have you gone up in an airplane or a helicopter to drop baits before yourself?

JORDONA KIRBY: Yes, I have. Absolutely.

JOHN DANKOSKY: So tell us what that’s like. Is it fun?

JORDONA KIRBY: Yes. It’s a really great experience. For me, personally– we’re in rural areas. We’re flying along the Appalachian Mountains in the eastern United States. Whether it’s in August or in October, it’s the best seat in the house. I mean, you see the mountains and the beautiful terrain. And you’re flying at a pretty low altitude.

So for nature lovers in particular, it really doesn’t get much better because you have this beautiful landscape out in front of you. You’re dropping the baits, so you know you’re doing something that is for the greater good in protecting wildlife and ultimately protecting people, pets, and livestock. And it’s a really great time. I do. I thoroughly enjoy it.

JOHN DANKOSKY: And I think it’s also really an interesting program because so many of the things that are targeted at stopping the spread of disease means the eradication of an animal, but what you’re essentially doing is saying, here, raccoon, have this tasty treat. It’s a little bit like getting some Halloween candy. And then all of a sudden, you’re vaccinated against rabies. You’re not going to pass it on to a dog or a human. It sounds like a very humane and lovely way to address this really serious problem.

JORDONA KIRBY: Yes. I mean, it is absolutely the most effective way to address a wildlife disease such as rabies, which, of course, has such significant potential public health impacts. And a lot of disease management involves culling populations, whether it’s highly pathogenic avian influenza or other similar diseases. But in our case, that’s absolutely not the goal. The intent is to vaccinate the animals and keep them healthy, which ultimately helps to keep pets and humans healthy as well.

JOHN DANKOSKY: You touched on this a little bit earlier, but it sounds as though this is part of a larger project to just get rid of rabies in the United States, not just amongst the raccoon population of the eastern half of the US, but just getting rid of the disease altogether. Where do we stand in terms of doing that?

JORDONA KIRBY: I think, honestly and realistically, that the ability to eliminate rabies altogether, as a whole, from the United States is very challenging. I still think we have a ways to go on that. One of our biggest challenges, though, with the ability to completely eliminate rabies, I would say, still exists with bats.

You know, bats are found throughout the country, similarly to some of these other species. But they have very different ecology. Obviously, they fly. They’re not a land-dwelling animal. There are no effective vaccines that we can use orally for bats at this time. And that’s why we specifically have chosen to focus on very specific variants, and in our case, raccoon rabies in the East.

Also, there’s a huge economic impact. In areas where raccoon rabies exists, more people are likely to be exposed. More pets are likely to be exposed. And then, if you look at the potential economic impacts in the absence of management, that gets pretty astronomical pretty quickly. So there are some huge economic advantages of continuing to conduct our program versus trying to look at overall rabies elimination across the country, because we just quite aren’t there yet when it comes to all species that potentially transmit the disease.

JOHN DANKOSKY: Jordona Kirby is the rabies field coordinator for the USDA’s National Rabies Management Program. Jordona, thank you so much for joining us. I really appreciate it.

JORDONA KIRBY: Thank you. Thank you very much.

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