Why Rodents (Rats) Do Not Transmit Rabies to Humans
Small rodents, including rats of all sizes, are almost never infected with rabies and have not been documented to transmit rabies to humans anywhere in the world. 1, 2
Epidemiological Evidence
The absence of rat-transmitted rabies is supported by decades of surveillance data:
From 1990-1996, in areas of the United States where raccoon rabies was endemic, rats were not significantly represented in rabies statistics among rodents, with woodchucks (a different rodent species) accounting for 93% of the 371 rodent rabies cases reported to the CDC. 1
From 2011-2020, a comprehensive analysis of 401 rabies cases in rodents and lagomorphs showed that groundhogs represented >90% of cases, while small rodents like rats, mice, squirrels, hamsters, guinea pigs, and gerbils remained essentially absent from rabies transmission data. 3
The percent positivity for rabies in rodents and lagomorphs was consistently <2.5% in any given year from 2011-2020, and this trend remained stable, with rats specifically showing negligible infection rates. 3
Why Rats Don't Transmit Rabies
The biological explanation involves several factors:
Small rodents likely do not survive the initial attack from a rabid carnivore (such as a raccoon, skunk, or fox) long enough to develop rabies infection themselves and subsequently transmit it. 1
Even when experimental infection has been attempted, rats show extremely low susceptibility to rabies virus, and natural transmission from rats to humans has never been documented in medical literature. 1, 2
Clinical Management of Rat Bites
When a patient presents with a rat bite, rabies postexposure prophylaxis is not indicated. 1, 2
The appropriate management algorithm is:
Immediately wash the wound thoroughly with soap and water for 15 minutes. 4, 5, 2
Apply a virucidal agent such as povidone-iodine solution to the wound after washing. 4, 5, 2
Assess for tetanus prophylaxis based on the patient's vaccination history. 5, 2
Consider antibiotic prophylaxis for bacterial infection, particularly rat bite fever (caused by Streptobacillus moniliformis or Spirillum minus), which is the primary infectious concern with rat bites—not rabies. 5
Consult local or state health department only if the rat's behavior was highly unusual or if there are other extenuating circumstances, though rabies remains extremely unlikely. 1, 5, 2
Critical Distinction from High-Risk Species
Do not confuse rat bite management with bites from high-risk rabies reservoir species:
Bats are documented rabies reservoirs in all 49 continental United States and require immediate postexposure prophylaxis, even for minor or unrecognized bites. 1, 4, 2
Wild terrestrial carnivores (raccoons, skunks, foxes, coyotes) are the animals most often infected with rabies and typically require immediate prophylaxis after any bite. 1, 4, 2
Woodchucks and beavers are the only rodent species with rabies percent positivity similar to high-risk species like bats and raccoons, but rats remain distinct from these larger rodents. 3
Common Pitfall to Avoid
The most important pitfall is unnecessarily administering rabies postexposure prophylaxis for rat bites, which exposes patients to the risks and costs of prophylaxis (including potential allergic reactions occurring in up to 11 per 10,000 vaccinees) without any documented benefit, as rats have never been known to transmit rabies to humans. 1, 2