Dr. Thompson: My sister-in-law contends that only animals with canine teeth can spread rabies. Is there any truth to her statement?
While I am not sure I want to interject myself into a family argument, she is not technically correct as it relates to the form that is present in North America. Rabies is a viral infection that affects the central nervous system that most often has skunks, foxes, bats, and raccoons as a reservoir for the virus. This means it primarily affects these animals but can infect any mammal. The Centers for Disease Control reported 6,154 animal and two human cases in the United States in 2011. On average more than 55,000 people die worldwide every year from rabies infections, mostly in Africa and Asia.
Spread of the virus is typically through a bite wound from an infected animal. However, the recent infection of transplant patients from infected organs highlights the fact that it can be spread through other avenues including contact with infected tissue or even inhaling virus particles. Cases have been documented in people breathing the aerosolized virus while exploring caves with high numbers of infected bats.
In North America the virus can infect mammals to varying degrees, including domestic pets, livestock, and horses. Some susceptible animals like cattle do not even have canine teeth. Small rodents such as squirrels, rabbits, and chipmunks are rarely known to be infected and have not transmitted the virus to people. Among pets, cats are three times more likely to become infected than dogs. This is most likely because cats are active at night, tend to fight when outdoors, and are vaccinated much less often against rabies than dogs. Even cats that do not go outdoors are at higher risk for exposure to rabies when bats get inside homes, which is a very common occurrence in our part of the world. For this reason cats should be vaccinated against rabies, regardless of whether they go outside.
Symptoms of animals infected with rabies can vary widely. The stereotypical rabid animal foaming at the mouth is something of an exaggeration and affected animals can have a wide range of symptoms. More accurately, any animal that is commonly infected with rabies such as raccoons, skunks, foxes, or bats demonstrating erratic or unusual behavior should be avoided. Any pet that is suspected of being exposed to any of these animals should be examined by a veterinarian and have its rabies vaccine booster and quarantined.
As it relates to your sister-in-law’s statement, she may have gotten some information about a family of viruses closely related to the rabies virus in Europe that infect only bats and carnivores who all have canine teeth. So if it helps keep the peace at the next family gathering, you could let her know she was partly correct.
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