Written by Stacey Elmore is a 2016-2017 Sustainability Leadership Fellow and Post Doctoral Researcher in the Department of Fish, Wildlife, and Conservation Biology.
About a month ago, I was walking my dogs around the apartment complex for their evening excursion. I bent over to untangle their leashes, and when I straightened up, I heard what can best be described as a “snorty growl” that sounded familiar, but I couldn’t quite place it. And it was very close to my face. I slowly turned my head to the left and locked eyes with a raccoon. The masked critter was also out for an evening jaunt, and had been sitting quietly in the tree – within spitting distance from my head!
As my brain connected the snorty growl with the presence of a raccoon, recognition took hold, and the familiarity became clear. As a post-doctoral researcher for Colorado State University and the U.S. Department of Agriculture’s (USDA) National Wildlife Research Center (NWRC), I encounter this sound frequently during my job duties. Luckily, healthy raccoons usually want nothing more than to be left alone by people, so my raccoon friend and I parted ways with no damage done.
I work with the rabies research group at the NWRC. A large portion of our group’s activities focus on studying the ecology of the raccoon (Procyon lotor) rabies virus, and the wildlife that transmit the virus to people and other animals. My job includes studying how raccoon movement influences the spread of disease, and which rabies management techniques might help to eliminate the virus from certain animal populations. This kind of investigation can not be done without collaboration, however, and I am fortunate to work with scientists from not only the NWRC, but also the National Rabies Management Program, Land and Sea Systems Analysis, Inc. (Quebec, Canada), and Colorado State University.
The Raccoon Rabies Virus
Rabies is an ancient disease that might bring to mind the dogs from the tear-jerking “Old Yeller”, or perhaps the horror movie “Cujo”. The rabies virus causes the disease “rabies”, which leads to inflammation of the Central Nervous System, including the brain. The virus travels mainly through nerves, but in the last stages of disease, it is also found in the salivary glands. When an infected animal bites a person or a pet, the rabies virus can enter the bite wound through the animal’s saliva. Although an encounter with an infected animal might not result in disease, rabies is 100% fatal in those unfortunate individuals that do show symptoms. This fact is scary - and is the reason that rabies is such a concern worldwide. The good news, however, is that rabies is also very preventable in people, pets, and many wildlife species through pre- and post-exposure vaccination, and a little common sense.
There are multiple genetic variants of the rabies virus, and each variant prefers to infect a different animal species. For example, the canine variant, which is what Old Yeller and Cujo likely suffered, no longer circulates in the United States, thanks to responsible pet ownership and dog vaccinations. Other variants, however, such as the ones that circulate in wildlife (bats, skunks, foxes, or raccoons), are not as easy to control. It seems that these species have a very difficult time keeping veterinary appointments!
Luckily for the wildlife, and for the general public, there is a federal program that organizes vaccine appointments on behalf of the animals – the National Rabies Management Program (NRMP). Along with the NWRC, the NRMP is part of the Wildlife Services program of the USDA Animal and Plant Health Inspection Service. The NRMP implements an oral rabies vaccination (ORV) program and other management techniques to control the spread of rabies virus in wild carnivore populations. Of all the rabies virus variants, however, the raccoon rabies virus variant receives the most intensive management. This variant is only found in the eastern U.S. and a vaccination zone stretches south from Maine to northern Alabama.
Every year, the NRMP drops around 8 to 10 million oral rabies vaccine baits from aircraft within targeted zones. To minimize the chance of a bait being picked up by people and pets, the program distributes baits by hand, helicopter, and bait stations in urban and suburban areas. The number of baits distributed in a particular area is determined by how many raccoons are likely to be living there and how many other animals might compete with the raccoons to eat the baits. The goal is to reach as many raccoons as possible to prevent the spread of rabies within and beyond the vaccination zones.
Raccoons populations aren’t declining… So why is this a sustainability problem?
Raccoons are a common, versatile and resourceful wildlife species. Unlike endangered species, whose limited or declining populations are easily linked to sustainability issues, abundant raccoons may seem out of place in this discussion. But, I’d argue that they do relate to sustainability because they are so abundant. Raccoon populations are the most dense in areas with lots of food, especially leftovers from people, and good places to hide during the day. Urban and suburban neighborhoods and parks fit this description, which brings a lot of raccoons into potential contact with a lot of people. When raccoon density is high, a rabies outbreak can move quickly through the population and chances of an encounter between a rabid animal and a person or a pet increase.
If a person is bitten or otherwise contacts the saliva of a potentially rabid animal, post-exposure prophylaxis (PEP) is administered and will prevent disease progression. In this event your local public health department is the first call that a person should make if he or she might have been exposed to a rabid animal. The public health workers will determine if PEP is warranted. Rabies PEP consists of a series of injections and it is very costly - roughly $3000 or more for one exposure event, and it is usually the patient who must pick up the bill. This is the crux of the sustainability issue with North American rabies. If we didn’t have to deal with raccoon rabies, how much of this money could be reassigned for other important and pressing ecological problems? There would still be a need for PEP in the U.S., but perhaps with a much lower frequency.
Recently, the NRMP met with rabies experts and stakeholders, to formulate a plan to eliminate the raccoon variant of the rabies virus from the eastern U.S. over a 30-year period. The plan entails moving the barrier eastward, as ORV efforts clear raccoon rabies from previously infected areas, according to carefully selected criteria. It is an ambitious goal, and also an achievable one. Through ORV activities, raccoon rabies has been largely eliminated from Canada, although the virus constantly challenges the southern regions of border provinces (i.e., Ontario, Quebec, and New Brunswick). Once the U.S. is declared free of raccoon rabies, the extreme need for PEP is expected to decrease over time and funds can be redirected to other sustainability needs. Also, by improving the health of raccoon populations, perhaps some of the fear of wildlife-associated diseases will abate.
But keep an ear out for that familiar snorty growl…the raccoons are not going to leave the neighborhood trash cans alone anytime soon…
Staying informed about rabies is a key prevention method for both people and pets. For more information, please visit the following websites: