Is it necessary to get a rabies vaccine after being scratched or bitten by a cat or dog?

Author: Tang Qin, Deputy Secretary-General of the Science Popularization Expert Committee of the Chinese Medical Association, Researcher

Reviewer: Wang Changyuan, Chief Physician, Xuanwu Hospital, Capital Medical University

Rabies is mostly spread through scratches and bites from dogs and cats carrying the rabies virus. When a sick dog or cat scratches or bites a person, the rabies virus will invade the human neurons and gradually spread to the nerve center, eventually reaching the brain and rapidly proliferating in the brain tissue, causing serious damage to the central nervous system, and this process is irreversible. Once rabies breaks out, the disease progresses very quickly, with a mortality rate of almost 100%, which is extremely harmful.

Figure 1 Copyright image, no permission to reprint

Although rabies is dangerous, it can be completely prevented if it is treated promptly and effectively. Let's learn what to do if you are scratched or bitten by a cat or dog.

1. Three types of wounds after being scratched or bitten by a cat or dog

After being bitten by a cat or dog, we should immediately observe the wound for subsequent handling and treatment. In addition, in addition to bites, scratches or licking of broken skin on the body may also spread the rabies virus.

Clinically, wounds after being scratched or bitten by a cat or dog are divided into the following three different situations according to the degree of exposure.

1. The first type : After being scratched or bitten by a cat or dog, the skin is intact and there are no teeth marks. This situation does not require treatment. Because the virus cannot infect the human body through the intact epidermis. If it is a minor scratch or bite by a cat or dog, as long as you observe carefully with the naked eye and find that the skin epidermis is not damaged, there is no risk of infection. If the naked eye cannot be completely sure, you can apply alcohol to the scratch or bite (note that it needs to be done within 2 hours, because some minor wounds can heal after 2 hours). If there is no tingling sensation, it means that there is no wound on the skin.

2. The second type : After being scratched or bitten by a cat or dog, there is no bleeding on the skin, only bite or scratch marks appear on the skin surface, and bruises can be seen in some wounds.

3. The third type : bleeding and open wounds after being scratched or bitten by a cat or dog.

In the second and third cases above, wounds need to be treated and rabies vaccines need to be administered. At the same time, if the scratches or bites are on the head or face, or if there are more serious injuries, such as single or multiple penetrating skin wounds, rabies immunoglobulin injections are also required.

Figure 2 Copyright image, no permission to reprint

Other situations, such as licking of broken skin or wounds, should be treated as bites. However, if the wound has scabbed over when licked, the risk of rabies infection can be ruled out.

2. How to deal with being scratched or bitten by a cat or dog

First , clean the wound, squeeze out the dirty blood in the wound immediately after being scratched or bitten, and rinse repeatedly with 20% soapy water and running water for at least 15 minutes. This is because soapy water is alkaline and can destroy the rabies virus.

Secondly , after cleaning the wound, in order to prevent the virus from invading the body to the greatest extent, you should use effective disinfectants to quickly kill the rabies virus. Do not apply gentian violet or mercurochrome at will. In terms of disinfection, you can use 2% iodine or 75% alcohol to rub the wound. Iodine has a strong permeability to tissues, mucous membranes, skin, etc., which is more conducive to the inactivation of the virus.

Finally , after flushing and disinfection, in order to prevent the virus from invading nerve fibers, the wound is not sutured or bandaged in principle. However, if the bitten person bleeds too much, such as if a large blood vessel is injured, the wound must be bandaged and sutured.

At present, rabies vaccination is still the only effective means of controlling rabies, so it should be administered within 24 hours of being scratched or bitten. The vaccination procedure includes the five-injection method, i.e., one injection each on the 0th (day), 3rd, 7th, 14th, and 28th day; the four-injection method, i.e., the "2-1-1 immunization procedure" on the 0th (day), 7th, and 21st day, i.e., two injections on the day, and one injection each on the 7th and 21st day.

Figure 3 Copyright image, no permission to reprint

In addition, if you are bitten or scratched by a cat or dog again within six months of completing the vaccination, you do not need to be vaccinated again; if it is more than six months and within one year, you should get one shot each on the 0th (day), 3rd day; but if it is more than one year, you should get one shot each on the 0th (day), 3rd day, and 7th day; if it is more than three years ago, you must complete the full vaccination process again.

In addition, for families with cats or dogs, the risk of rabies transmission can be reduced by giving their cats or dogs rabies vaccines. At the same time, if the cat or dog that bites a person is a healthy domestic pet with a clear history of two doses of vaccination and has not been bitten by a suspected mad dog or other animal in the past six months, the bitten person can first receive one shot of the vaccine and then observe the cat or dog for 10 days. A large number of studies have shown that if the cat or dog that hurts a person is still alive and well after 10 days, it means that its saliva did not contain rabies virus when it bit a person, so there is no need to worry about transmission to humans. In this case, the remaining vaccines generally do not need to be vaccinated.

References

Jiang Lei. Do not neglect thorough wound debridement before rabies vaccination[J]. Yishou Baodian, 2020, (4): 87.