Opossums are common marsupials found across North America, known for their adaptability to diverse environments, including urban areas. These nocturnal animals often forage for food at night, sometimes leading them into human-populated spaces. As with any wildlife, concerns about disease transmission, particularly rabies, can arise when encountering opossums.
Opossums and Rabies Risk
While any mammal can contract the rabies virus, it is rare for opossums to be found with the disease. Data indicates that less than one percent of all reported wildlife rabies cases in the United States involve opossums. This incidence rate is significantly lower compared to other wildlife species commonly associated with rabies, such as bats, raccoons, skunks, and foxes.
Specific studies reveal that less than 1 in 1,000 tested opossum specimens are infected with rabies. This low prevalence means that encountering a rabid opossum is an uncommon event. Despite their presence in various habitats, their role in the transmission of rabies to humans or domestic animals is considered exceedingly minimal.
Why Rabies is Rare in Opossums
The primary reason for the opossum’s resistance to rabies is its distinctive body temperature. Opossums maintain an average body temperature of 94 to 97 degrees Fahrenheit (34.4 to 36.1 degrees Celsius). This cooler internal environment creates an unfavorable condition for the rabies virus. The virus struggles to replicate and spread effectively within a host whose body temperature is below the optimal range for its survival.
While low body temperature is the leading factor, their robust immune system also contributes to their resistance. These physiological traits make it challenging for the rabies virus to thrive, contributing to the very low incidence of the disease in opossum populations.
Encountering an Opossum: What to Know
When you encounter an opossum, it is important to understand their typical behaviors. Opossums are generally non-aggressive animals that prefer to avoid confrontation. If threatened, they often display defensive behaviors such as hissing, drooling, baring their teeth, and swaying. These actions are usually bluffs intended to deter potential predators and should not be mistaken for signs of rabies.
Another defense mechanism is “playing dead” or thanatosis, where the opossum enters a catatonic state, appearing stiff and unresponsive. An opossum exhibiting unusual behavior like disorientation, aggression, or excessive drooling is likely suffering from another illness, injury, or displaying these defensive tactics, rather than rabies. It is always important to avoid approaching or attempting to handle any wild animal. If you encounter an opossum that appears sick or injured, the appropriate action is to contact local animal control or a licensed wildlife rehabilitation service for assistance.