Mammals are the only natural vectors for the deadly virus rabies. The disease is spread among mammals through the saliva and typically associated with a bite. The virus travels the body to the brain via the nervous system, and therefore its incubation period is proportional to the distance from the bitten area to the head. The symptoms of rabies generally don't appear until the disease reaches the brain and often just a few days before imminent death. Therefore, any person that has been in contact with a rabid animal should be examined by a physician in a timely manner. Tests are not available to diagnose the disease prior to the onset of symptoms; however the available treatments are successful when rabies is caught early.
The most well-known and feared disease spread from animals to humans is rabies. Bats are the most common vector of rabies to human hosts, according to the U.S. Centers for Disease Control and Prevention, or CDC 2. Bats can be found on every continent except Antarctica and become increasingly abundant towards the tropics. Additionally, many species of bats that inhabit temperate regions are migratory, making annual flights to areas where rabies is much more prevalent. The transmission of rabies from a bat to a human is made through a bite as it is with other animals; however, most bats are small and their bites are liable to be painless. A household that awakens to find a bat in their home should seek medical advice.
Raccoons and Skunks
Owing to aspects of their biology, raccoons and skunks are among the most commonly listed vectors for human rabies transmission, according to the Mayo Clinic 3. Both mammals are found throughout the United States, much of Canada, and each range well into Central and South America. Raccoons and skunks are successful cohabitants with humans, increasing the potential interactions of all three. And finally, unlike most small rodents, raccoons and skunks are capable of inflicting a serious bite, increasing the chance of the virus being transmitted.
In India, where rabies is much more prevalent that it is in the United States, the principle animal vectors are wild dogs, according to the World Health Organization 1. Fortunately, that is not the case in the US; however, other wild canids including the coyote and several species of fox are all known potential carriers of the rabies virus. Each of these canid species is widespread and while they are not quite as habituated to humans as are raccoons and skunks, they are still common residential visitors, albeit more secretive. Rabies infected animals, including humans, become disoriented and unpredictable toward the later stages of the disease. These relatively large canids may lose their shyness and are certainly capable of delivering a significant bite.
Other Mammal Vectors
The Mayo Clinic lists several other domestic and wild animals that often come in close contact with people and for which rabies cases have been recorded 3. These mammals include cats, dogs, cows, ferrets, goats, horses, rabbits, beavers, monkeys and woodchucks. It is important to remember however, that any mammal is capable of hosting and spreading the rabies virus. People who suspect they have been bitten by a potentially rabid animal should seek medical attention immediately. Preventative vaccinations are available, and generally recommended for individuals that spend much of their time around potentially rabid animals.
- raccoon image by antoine perroud from Fotolia.com