Illinois Natural History Survey - University of Illinois

Raccoon Health Watch

Late at night you may hear rustling in your garbage or see a fat, sleek animal bandit dash across the street. Raccoons are becoming more and more common in suburbs and towns as well as in rural areas. The increase in Illinois wildlife enhances our environs, but human-wildlife interactions can also have some negative consequences.

The Illinois Natural History Survey Center for Wildlife Ecology and the University of Illinois College of Veterinary Medicine have been collaborating on a study to evaluate the health of wild raccoons. Raccoons were given physical examinations and blood and fecal samples were collected to test for diseases that can be harmful to humans, pets, or livestock.

One of the most common infections found in raccoons was leptospirosis. Almost 50% of the healthy raccoons showed current or previous infections with Leptospira bacteria. This organism can also spread to humans and their pets causing ailments ranging from mild, flu-like symptoms to severe disease. Leptospirosis is transmitted when the bacteria, which are usually excreted in urine, come in contact with mucous membranes or broken skin. The organisms can survive for long periods of time in warm, stagnant water. People handling raccoons should wear gloves and those engaging in recreational activities in areas of high raccoon density should be made aware of the risks. In Hawaii, signs are posted along many streams and wetlands warning of the hazards of leptospirosis; however, the risk there is higher because of the warmer climate.

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An urban raccoon.

Infection with canine distemper virus ranged from 20% to 30% across the three years of the study. Deaths due to distemper occurred every year and an outbreak, with considerable mortality, occurred in one area. The virus also seemed to cause a generalized suppression of the raccoons' immune systems, resulting in susceptibility to other parasites and diseases. Distemper is not a zoonosis, so humans cannot get the disease. However, distemper from raccoons does pose a hazard for pet dogs that are not properly vaccinated. Distemper is also a major source of mortality for raccoons, especially in areas of high density. Recent studies suggest that this raccoon/canine virus may cause severe disease in exotic cats, such as lions and panthers. Raccoons should not be transported from one area to another because they may start epidemics among other raccoons or dogs. All dogs that have contact with wildlife should be regularly vaccinated for distemper.

Almost half of the raccoons had antibodies to toxoplasma and the infection rate increased with age. Although cats (both domestic and wild) are the only species that can shed toxoplasma eggs, many other species, including humans and raccoons, can become infected. In humans, infection is inconsequential unless it occurs for the first time in a woman, while she is pregnant. If the organism is passed to the fetus, severe birth defects can result. Toxoplasmosis can also be life threatening for AIDS patients and patients on chemotherapy for cancer or organ transplants. Illinois raccoons thus serve as a sentinel of toxoplasma in the environment as well as a source of infection for humans who consume raccoon meat. Pregnant women and people experiencing immunosuppression should be careful to avoid contact with soil when in natural areas. The microscopic toxoplasma eggs must be ingested to be infective; however, eating without washing hands could allow infection.

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Raccoon with dental problems caused by ingesting human food.

Several of the agents identified in fecal samples (Bayli-sascaris procyonisCapillaria sp., and hookworms) pose health hazards for humans and domestic species, especially birds, dogs, and exotic animals. Contaminated soil serves as the main source of exposure. Raccoon feces should not be allowed to accumulate in areas used recreationally by humans or around homes. Facilities for hand washing should be readily accessible in picnic areas. Although humans are not likely to be exposed by close contact with raccoons, raccoons often defecate near where they feed; therefore, feeding raccoons should be discouraged.

Raccoons also showed some negative effects following association with humans. Raccoons that lived in a state park and were fed by visitors had higher rates of dental caries and gum disease as well as higher cholesterol levels than those living in a farming area.

Further studies are continuing to examine the health of raccoons in urban areas and to evaluate how diseases affect animal behavior and movements. By better understanding the potential for disease occurrence at the interface between humans and wildlife, we can take measures for humans to enjoy wild species while minimizing health hazards to humans, pets, and wildlife.

Laura Hungerford, Center for Wildlife Ecology



Illinois Natural History Survey

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