Rabies is a deadly viral disease that attacks the central nervous system in mammals, including humans. Once symptoms appear, the illness is almost always fatal, making prompt medical care following exposure necessary for prevention. Rabies exposure from rats, mice, and other small rodents is extremely rare, particularly in the United States. Public health officials generally do not consider rats a significant source of human rabies infection.
Why Rabies Transmission from Rats is Rare
The low risk of rabies transmission from rats and other small rodents is due to biological and epidemiological factors. Rats, mice, squirrels, and rabbits are rarely found infected with the rabies virus in the wild. The Centers for Disease Control and Prevention (CDC) notes that no human rabies deaths have ever been associated with rodents or lagomorphs in the United States.
A factor contributing to this rarity is the survival rate of small animals when attacked by a rabid predator. When a larger, rabid animal like a fox or raccoon bites a rat, the small rodent often sustains immediately fatal injuries or dies shortly after the attack. This lack of survival time means the rat does not live long enough for the rabies virus to incubate, travel to the salivary glands, and reach a concentration high enough for transmission through a subsequent bite.
Small rodents are not considered a natural reservoir for the virus, meaning the disease does not circulate and sustain itself within their population. While any mammal can be infected, the vast majority of documented rabies cases in rodents are found in larger species like woodchucks (groundhogs) and beavers. These larger rodents account for over 97% of reported rabid rodents in the US between 2011 and 2020 and are more likely to survive an encounter with a rabid animal, allowing the infection to progress. For the common rat, the risk is so minimal that health authorities rarely recommend post-exposure prophylaxis (PEP) unless the circumstances are highly unusual.
Primary Carriers of Rabies
The danger of rabies transmission in North America lies almost entirely with specific wildlife species that serve as primary reservoirs for the virus. These animals are capable of carrying and spreading the disease within their populations, often without dying immediately after infection. The majority of animal rabies cases reported annually in the United States occur in wild animals, with four species accounting for the largest percentage of infections.
The most common carriers are bats, raccoons, skunks, and foxes. Bats are a leading cause of human rabies deaths in the US, often because their bites are so small they go unnoticed. Raccoons and skunks are widespread vectors, especially in the eastern and south-central United States. In certain regions, foxes and coyotes also maintain the rabies cycle.
Domestic animals, such as dogs and cats, are far less common sources of rabies in the US due to widespread vaccination programs. Unvaccinated domestic pets that encounter rabid wildlife can contract the virus, making up-to-date vaccinations a necessary public health measure. Globally, unvaccinated dogs remain the source of the vast majority of human rabies deaths.
Immediate Steps Following an Animal Bite
Even though the risk of rabies from a rat is low, a bite or scratch from any wild or unfamiliar animal requires immediate steps to prevent infection. The most important action is immediate wound care. The wound must be thoroughly washed with soap and running water for five to ten minutes, as this physical cleaning dramatically reduces the amount of any potential virus or bacteria.
After cleaning, prompt medical evaluation is necessary to assess the injury and determine the need for further treatment. A health care provider will assess the wound for severity, check if a tetanus booster is required, and determine if antibiotics are necessary to prevent bacterial infection. Rat bites, while low-risk for rabies, carry a risk of bacterial infections like rat-bite fever.
The third step involves consulting with a public health professional, usually done by the medical provider contacting the local health department. This consultation helps determine the need for Post-Exposure Prophylaxis (PEP). PEP involves a series of vaccines and, in some cases, a dose of rabies immune globulin. This time-sensitive procedure is typically only recommended following a rat bite if the animal showed unusual behavior or if the local health situation warrants it.