Cat Bite or Scratch: Do You Need Rabies Vaccine?

Understanding Rabies

Rabies, known as hydrophobia in English, is an acute infectious disease caused by the rabies virus. It is zoonotic, meaning it can be transmitted between humans and animals, and is widely found in wildlife and domesticated animals (warmblooded creatures). The disease manifests in humans with symptoms such as hydrophobia (hence the name hydrophobia), fear of wind, spasms of the throat muscles, paralysis, and more.

Unfortunately, there is no effective treatment for rabies after it has developed, and the fatality rate is almost 100%. Patients typically die within a week due to respiratory or circulatory failure.

How is Rabies Spread?

The rabies virus enters the body through direct contact with an open wound or mucous membrane surface. It travels along nerves to the brain, attacking the central nervous system of humans and animals, and is transmitted to other animals or humans through saliva.

Which Animals Can Transmit Rabies to Humans?

Almost all warmblooded animals can be infected with the rabies virus, but mammals are primarily at risk. This includes animals from families like canids, felids, mustelids, procyonids, rodents, and bats. To put it simply, statistically, 99% of rabies cases in humans worldwide are from dogs (which is why domestic dogs must receive a rabies vaccine annually), with the remaining 1% being from cats (mainly) and other animals. This means that in the sources of human rabies infection, less than 1% are transmitted by cats.

What is the Probability of Cats Contracting Rabies?

Domestic cats, unlike dogs, do not require regular walks outside and are less likely to come into contact with the environment, including other cats, dogs, and even rodents and stray dogs. Cats are mostly indoor pets, and rabies is primarily transmitted through saliva, meaning that most infections occur through being bitten. The likelihood of being scratched is low.

Since the rabies virus has a very short lifespan outside the body, if the saliva containing the virus comes into contact with the skin and there are no breaks, the virus will essentially die off within minutes. If it comes into contact with other items, the virus will also die off after the item dries. Therefore, indoor cats that never go outside have almost zero chance of being infected.

How Can Cats Transmit Rabies to Humans?

Rabies is not something that just appears out of nowhere; it is transmitted. Therefore, for a cat to transmit rabies to a human, it must already be carrying the virus. Healthy cats do not transmit rabies to humans.

If a cat不幸 becomes infected with the rabies virus, it is not easy to transmit it to humans. This requires specific conditions:

Incubation Period: The virus is present in the cat but the cat is completely normal and has not yet shown symptoms. During this time, it cannot transmit the virus to humans or other animals. The incubation period for animals is between 10 days and 6 months, and cannot be longer.

Onset Period: The cat has carried the rabies virus and has now entered the onset period, where it shows abnormal behavior. During this time, the cat can transmit the virus to its owner, as the virus is present in the cat's saliva, and transmission occurs through saliva.

So, if the cat bites its owner during this stage, it can transmit the virus. The likelihood of transmission through a scratch is much lower than through a bite, as a scratch primarily causes a wound, while a bite must cause a wound and expose it to the toxic saliva. A scratch can only transmit the virus if the cat has just licked its claws (remember that the virus has a very short survival time outside the body), or if the saliva comes into contact with the wound in some other way, such as splashing or dripping onto the wound.

WHO's TenDay Observation Method

The World Health Organization (WHO) has recognized and recommended the "TenDay Observation Method" for rabies in official documents:

After a suspected cat or dog bites a person (exposure), the wound should be immediately cleaned and disinfected, and the biting animal should be quarantined for observation. If the animal remains healthy during the 10day observation period following exposure, it can be concluded that the animal is not infectious.

This means that if you are bitten by a stray cat and cannot determine whether it has been in contact with other animals or whether it carries the rabies virus within the past six months, you can follow the TenDay Observation Method. If the cat remains healthy and active after 10 days, you can be confident that you will not be infected with rabies.

Because infectious cats can only transmit the virus during the 3 days before the onset of symptoms and the entire onset period, if the cat does not show signs of illness within 35 days of biting you, it means that the time of the bite was not within the infectious range (of course, not during the onset period). If the cat does not show signs of illness within 5 days, it can be considered relatively safe.

However, the WHO has extended the observation period to 10 days to provide a sufficient margin of safety. If there are no problems within 10 days, you can be 100% confident that you are safe.

What Should I Do About Vaccination?

If your cat meets the following criteria—indoor, not exposed to other suspicious animals in the past six months, and has received a rabies vaccine within the past year—you do not need to be vaccinated.

So, keep your cat indoors and away from other suspicious animals. Even if you are scratched or bitten, you can simply rinse and disinfect the wound.

If the cat that scratched or bit you cannot be judged according to the aforementioned methods, and you are unsure whether it carries the rabies virus or is in the infectious period, follow the standard procedure:

Just petting the cat or being licked by the cat on healthy skin (no open wounds) does not require any treatment.

For light bites or scratches without bleeding, wash the wound with soap and water (or clean water) for 15 minutes and go to get the rabies vaccine as soon as possible.

For puncture wounds or scratches that break the skin, or if the wound is licked by the cat, rinse the wound and go to get the rabies vaccine and immune globulin as soon as possible.

During the time you are receiving the vaccine, follow the TenDay Observation Method and isolate the cat that bit you. If the cat remains healthy and shows no signs of illness after 10 days, you do not need to receive any more rabies vaccines.