[Previous article] The many complications of rabies

This is the 3623rd article of Da Yi Xiao Hu

1. Can a dog that looks healthy actually carry the rabies virus?

The health here has two meanings. One is long-term health, and the other is health at a certain point in time. (1) Surveys on the rabies virus carrier rate of apparently healthy dogs conducted in many places show that although the positive rate is usually not high (at the level of one in a thousand), rabies virus can indeed be detected in apparently healthy dogs (the surveys usually come from dogs for sale in the market and stray dogs) (using the method of testing brain tissue after euthanasia).

(2) However, it is impossible for a dog to carry the rabies virus for a long time without becoming ill. Studies have shown that the longest incubation period in dogs is half a year. Therefore, if a dog has not had contact with the outside world within six months or has not been bitten by wild dogs or cats, the possibility of it carrying the rabies virus can be ruled out.

EXPLANATION

Interpretation

The dogs whose brain tissues were found to have rabies virus were in the incubation period. However, it should be noted that carrying the virus does not mean that it is contagious at all times. The rabies virus and other viruses (such as hepatitis virus, varicella virus, etc.) have completely different characteristics, which we will discuss below. 2. Is it possible that domestic dogs are the source of rabies?

A survey of rabies patients reported in my country in recent years showed that more than 90% of the injured animals were dogs, and domestic animals were very common, especially in rural areas, where a large proportion of the cases were caused by being bitten by their own or neighbors' dogs.

EXPLANATION

Interpretation

Domestic dogs may be bitten by wild dogs and cats, thus becoming new sources of infection, so domestic dogs do not spread rabies. 3. Will all people bitten by dogs develop symptoms of rabies, just sooner or later?

First of all, rabies is a disease with a very low morbidity and a very high mortality rate. In the vast majority of cases, dogs that bite or scratch people do not have the rabies virus in their bodies (in many cases, biting people does not necessarily mean that the dog has rabies), so in this case, it is impossible for the disease to occur. Secondly, even if you are bitten by an animal with rabies, you may not be infected. After a dog or cat is infected with the rabies virus, it is generally believed that the toxins can be intermittently excreted through the salivary glands, that is, the saliva of a rabid dog or cat does not always carry the virus. If the salivary glands are not excreting toxins when the dog bites someone, then in this case, even if no standardized treatment is performed, the person will not be infected. This is why not all victims have the same outcome in the same mad dog bite incident.

EXPLANATION

Interpretation

Even so, we cannot be sure whether the virus has entered the human body at the time of being bitten. Since the mortality rate of rabies is too high, we cannot take chances, and this phenomenon cannot be a basis for refusing vaccination.

4. Is it possible that anyone who comes into contact with the saliva of a mad dog will be infected with rabies?

Strictly speaking, the spread of rabies requires several conditions, which is not easy to achieve. First, the dog's salivary glands are in the detoxification stage at this time, and the saliva contains viruses. Second, the virus in the saliva must be able to enter the human body. Since the virus cannot penetrate intact skin, from the perspective of the virus, it requires an animal with rabies to inject the virus in the saliva into the new host through biting, scratching, etc.

EXPLANATION

Interpretation

The essence of this question is that while we should pay attention to rabies, we should not panic and become a "rabies phobic". Especially when the skin is intact, the virus cannot penetrate into the human body. 5. Do contagious dogs always show obvious symptoms?

There are two types of rabies, one is the manic type, which accounts for the majority, and the other is the paralytic type, which accounts for a relatively small proportion. Another problem is that the virus can be detected in the salivary glands of rabid animals a few days before the onset of obvious symptoms. If bitten at this stage, it is also possible to be infected. The symptoms at the time of the incident (biting people, etc.) cannot directly determine whether it is contagious.

EXPLANATION

Interpretation

After being bitten by a cat or dog, the most reliable approach is to standardize wound treatment and use rabies vaccine/protein, and this needs to be started as soon as possible. Please cooperate with the doctor's risk assessment of exposure. 6. Does one have to be scratched or bitten by an animal to get rabies?

Currently, the main route of rabies transmission is bites, with scratches accounting for a relatively small proportion. Other common routes include licking wounds.
Other less common routes include: (1) Aerosol transmission: This may occur when laboratory workers performing rabies virus-related tests enter caves where large numbers of bats live.

(2) Organ transplantation: The organ donor has a virus in his body, and the recipient becomes ill after the transplant.

(3) Dissecting, slaughtering, and skinning rabid animals may occasionally result in infection; however, infection from eating raw meat of animals that have died of rabies (the meat contains the rabies virus) is rare.

Ways in which rabies will not be transmitted: (1) Thoroughly cooked animal meat and pasteurized milk will not transmit rabies.

(2) Rabies is not transmitted vertically from mother to child. Newborn puppies do not carry the virus.

EXPLANATION

Interpretation

Some people worry that the saliva of rabid animals may get on the surface of objects and then accidentally touch their bodies, and then they find wounds on their hands or feet, and thus suspect that they may be infected with rabies. In fact, this panic is very similar to "AIDS phobia". This indirect transmission route of infection is only theoretically possible. After all, this is a rabies virus, not a respiratory or enteric virus. The main route of normal infection is still bites and scratches from dogs and cats that break the skin and bleed. Chief Advisor: Professor Jiang Qingwu Medical Advisor: Zhao Wensui, Chief Physician of Changning District Center for Disease Control and Prevention, and Cai Enmao, Chief Physician

IT technical support: Shanghai Yuemi Information Technology Co., Ltd.

Medical content: Zhuang Jianlin famous doctor studio Editor: Zhang Zhan Gao Hui

Funding project support:

National Natural Science Foundation of China "Response, Governance and Impact of Public Health Events Such as the COVID-19 Pandemic" Special Project - Project Name: Response and Governance of Public Opinion in Major Public Health Emergencies (Project Approval No.: 72042004)

This project was supported by the Shanghai Municipal Science and Technology Commission's Science Popularization Project (Project No.: 18dz2300700).

Changning District Fourth Round (2018-2020) Innovation Team (Reserve) (Innovative R&D team for infectious disease prevention and control based on artificial intelligence and original IP system)

Medical specialty in Changning District: Acute infectious disease prevention and control department (acute infectious disease monitoring and prevention and control in schools)

Changning District Center for Disease Control and Prevention Innovation Team: Visual Health and Health Science Team

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All names and place names are pseudonyms and any similarity is purely coincidental.