A disease of wildlife called tularemia, a.k.a. “rabbit fever,” has been reported in every state except Hawaii, according to Kelly Rockwell, a third-year student at the University of Illinois College of Veterinary Medicine who co-manages the student-run Wildlife Medical Clinic.
“Tularemia has been around a long time. It is getting a lot of press lately because of recent cases in the area,” says Rockwell.
The Centers for Disease Control and Prevention recorded 203 human cases of tularemia in the United States in 2013. Four of these occurred in Illinois.
The disease is caused by the bacterium Francisella tularensis. Symptoms typically develop three to five days after exposure and can be flu like, including fever, sore and enlarged lymph nodes, headache, diarrhea, joint pain, and general weakness. In more serious cases, skin and oral ulcers can develop, and the infection can be fatal.
Although the disease is called “rabbit fever,” Rockwell explains that rabbits are not the only animals that carry it.
“Rodents can also carry it, including mice and bigger rodents such as groundhogs. They may or may not be symptomatic when they are infected, and the disease can be transmitted to humans and pets.”
The most common source of infection in people is via insect bites, such as those from ticks, fleas, and deerflies (in the Western United States), that bite infected animals and transmit the bacterium to humans and other animals.
“We see more cases from May to September because insects are more active during that time,” Rockwell notes.
The bacterium may be present in contaminated water, in the body and on the fur of infected animals, and in their fecal material. Handling infected animals without protective gloves or clothing and eating undercooked meat of infected animals are routes of infection. Dogs and cats become exposed when eating infected carcasses and, although rarely, people have been infected through contact with their sick cat. Less commonly, the bacterium can become aerosolized during mowing of fields in endemic areas and spread through the air.
“Anything that can be contaminated, including water, meat, and fecal material, can contain the pathogen,” says Rockwell.
For this reason, it is not recommended to allow dogs or cats outside unsupervised where they may try to hunt or come in contact with infected wildlife. Cats are at increased risk due to their inherent hunting behavior and are highly susceptible to tularemia, whereas dogs seem to be resistant to infection. Clinical signs of tularemia in animals may be mild to severe and are similar to those seen in people, including listlessness, fever, swollen glands, and loss of appetite. Less commonly animals may develop a cough, vomiting, diarrhea, stiffness, or skin ulcers.
Contact with a person that has tularemia will not give you the disease. “People get tularemia only from an infected animal or the bite of an infected insect, not person to person,” explains Rockwell. Larger outbreaks among humans have not occurred because of this fact.
If a person or pet does contract the disease, medical help should be sought immediately. “Your physician and your pet’s veterinarian will be able to confirm the infection through diagnostic testing, and antibiotics are the most effective treatment if started at the first signs of the illness,” says Rockwell.
So how do we protect ourselves from this disease? Rockwell advises, “If you find a sick or dead wild animal, do not touch it with your bare hands and keep your pets away. The most important thing is to not touch wildlife,” Rockwell stresses. “It may seem like a good idea to take a sick animal into your home and care for it, but it can really get you or the animal sick.”
When handling an animal carcass, use rubber gloves and a secure receptacle to dispose of it. The Illinois Department of Natural Resources investigates wildlife disease outbreaks and may be contacted to determine if testing of the animal is recommended. Additional protective measures include using insect repellents for both people and pets, and diligence in removing ticks as soon as detected. Avoid eating undercooked meat or consuming contaminated water.
For more information about tularemia, visit the Centers for Disease Control and Prevention website. If you find a sick or injured animal, call the University of Illinois Wildlife Medical Clinic at (217) 244-1195 or your local wildlife clinic for further instruction. More information about wildlife and the Wildlife Medical Clinic may be found at vetmed.illinois.edu/wmc/.
By Melissa Giese