Rabies is transmitted through the saliva of an infected animal, most commonly via a bite that breaks the skin. Dogs cause up to 99% of human rabies cases worldwide. The virus can also enter through scratches, open wounds, or mucous membranes (eyes, nose, mouth) that come into contact with infected saliva, though these routes are far less common.
What Happens After the Virus Enters Your Body
Once rabies virus gets past the skin, it doesn’t immediately race to the brain. It may first replicate quietly in muscle tissue near the wound, staying close to the entry site for weeks or even months. This silent phase is the incubation period, and it’s the window where post-exposure treatment can stop the infection.
Eventually, the virus reaches a nerve ending, often at a neuromuscular junction where nerves connect to muscle. From there, it travels along peripheral nerves toward the spinal cord and brain. This journey is one-directional and relatively fast once it begins. After the virus reaches the central nervous system and starts replicating there, the infection is almost always fatal. The median incubation period in humans is about 52 days, but it can range from as short as 6 days to, in rare documented cases, nearly 3 years. Bites closer to the brain, like on the face or neck, tend to produce shorter incubation periods because the virus has less distance to travel.
Dogs, Bats, and Other Animal Sources
Globally, domestic dogs are overwhelmingly the primary source. In countries with effective dog vaccination programs, like the United States, Canada, and most of Western Europe, wildlife becomes the main concern instead. Raccoons, skunks, foxes, and bats are the most common wild carriers in North America.
Bats deserve special attention because their bites can be so small you may not realize you were bitten. A bat bite can look like a tiny scratch or leave no visible mark at all. This is why public health authorities treat any direct contact with a bat as a potential exposure, especially if you wake up to find a bat in your room, or if a bat was near an unattended child or someone who couldn’t report a bite.
Small rodents like mice, rats, squirrels, and rabbits are almost never found to carry rabies. A bite from one of these animals rarely warrants rabies treatment.
Non-Bite Routes of Transmission
Bites account for the vast majority of cases, but they aren’t the only route. Rabies virus can be transmitted through direct contact of saliva, tears, or nerve-rich tissues from an infected animal or human with broken skin or mucous membranes. If an infected animal licks an open wound or your eyes, that counts as a potential exposure.
Scratches from rabid animals also pose a risk, particularly if the animal’s claws have been contaminated with saliva. The WHO includes scratches alongside bites as a cause of human rabies cases.
Human-to-human transmission is exceptionally rare but has occurred through organ and tissue transplantation. A 2025 CDC report confirmed a fatal rabies case in a patient who received a kidney from a donor with undiagnosed rabies. Between 1978 and 2013, three separate transplant-transmitted rabies events in the United States affected nine recipients total. Corneal transplants carry particular concern because the cornea and optic nerves sit so close to the brain, potentially shortening the incubation period.
When Infected Animals Become Contagious
An animal doesn’t need to look sick to be shedding the virus. Dogs, cats, and ferrets can have rabies virus in their saliva three to six days before any visible symptoms appear. Once clinical signs do show up, these animals typically survive only a few days. This is the basis for the standard 10-day observation period: if a dog or cat that bit you is still alive and healthy after 10 days, it was not shedding rabies virus at the time of the bite.
Wildlife cannot be reliably observed this way, which is why a bite from a wild mammal, especially a raccoon, skunk, fox, or bat, is generally treated as a rabies exposure unless the animal can be captured and tested.
How Long the Virus Survives Outside the Body
Rabies virus is fragile outside a living host, but it doesn’t die instantly. Research using virus from the salivary glands of infected foxes found that on surfaces like glass, metal, and plant leaves, the virus could survive up to 24 to 48 hours at room temperature (around 20°C). At refrigerator temperatures (5°C), it lasted up to 144 hours, or six days. Heat and direct sunlight kill it much faster: at 30°C with intense sunshine, the virus was inactive within 90 minutes.
In practical terms, you’re unlikely to contract rabies from touching a surface. The virus needs to reach a nerve, which means it has to get through broken skin or a mucous membrane in sufficient quantity. Dried saliva on an object is not considered a meaningful exposure risk.
What Post-Exposure Treatment Involves
If you’re potentially exposed, treatment is straightforward and highly effective when started promptly. The first step is thorough wound washing with soap and water, which alone significantly reduces risk. For someone who hasn’t been previously vaccinated, the full course includes an injection of rabies immune globulin (administered around the wound site on the first visit) plus four vaccine doses spread over two weeks, given on days 0, 3, 7, and 14. People with weakened immune systems receive a fifth dose on day 28.
If you’ve been vaccinated against rabies before, treatment is simpler: just two vaccine doses, three days apart, with no immune globulin needed.
The critical point is timing. Because the virus can sit quietly near the wound for weeks before reaching the nervous system, starting treatment days or even weeks after a bite can still be effective. But once symptoms appear, no treatment has been proven to reliably save lives. This is why any credible exposure to a rabid or potentially rabid animal should be treated as urgent, even if you feel completely fine.