The source of the new coronavirus is wild animals! What are the natural epidemic sources and arbo-borne diseases that you should know?

On January 22, 2020, Gao Fu, a member of the Chinese Academy of Sciences and director of the Chinese Center for Disease Control and Prevention, said at the State Council's press conference: The source of the new coronavirus is illegal wildlife sold in a seafood market in Wuhan.

In addition, Tongji Hospital affiliated to Huazhong University of Science and Technology held a media meeting on January 22. At the meeting, Zhao Jianping, director of the respiratory department of Tongji Hospital, Ning Qin, director of the infection department, and Li Shusheng, director of the ICU of the emergency department, announced to the media: After virus sequence alignment analysisIt is speculated that the natural host of the new coronavirus disease may be bats.

Natural epidemic sources and arboviruses are a class of infectious diseases of legal infectious diseases. They mainly refer to infectious diseases that use animals including arthropods as the source of infection and can exist independently in nature without relying on people.

Natural epidemic diseases have typical regional, obvious seasonal and occupational correlations

The pathogens of natural epidemic diseases are hosted by wild vertebrates. Because the pathogens only circulate in specific biomes, and specific biomes only appear in specific areas, this has led to the typical of natural epidemic diseases.Regional.

The transmission of pathogens in natural epidemic diseases should be arthropods. Because the number of media and the activity are changed with the seasons, they are greatly affected by temperature and humidity, which leads to natural epidemic diseases in animals.Or human epidemic shows obvious seasonality.

Natural epidemic diseases are significantly affected by human economic activities, such as reclamation, water conservancy construction, afforestation, and other activities often destroy or change the original biological community, so that the living environment of the host and vector on which the pathogen depends depends on survival and circulation.Changes can lead to the enhancement, reduction or disappearance of natural epidemic diseases, and even lead to new natural epidemic diseases that did not exist locally.

Host of pathogen of natural epidemic disease

The host of the pathogen of natural epidemic diseases includes vertebrates and even some invertebrates, such as the intermediate host of snails of Schistosoma. It can be said that the host of most natural epidemic diseases is rodents, such as plague, forest encephalitis, bleedingFever, tsutsugamushi, etc. are hosted by rodents.

We divide it into three types: primary host, secondary host, and accidental host. For example, marmot and weasel are the main hosts of plague, that is, the host of pathogens to keep their populations in circulation for a long time.Origin does not exist.

Secondary hosts do not play a fundamental role in maintaining the natural epidemic source, but they can cause epidemics and pose a great threat to humans, especially some home-based amphibious secondary hosts that often have access to people and often becomeThe main source of the disease's epidemic, such as Mus musculus, the secondary host of plague.

Accidental host, if its name is accidentally involved in animal disease epidemic, can sometimes infect humans and cause epidemics. In many natural epidemic diseases, humans can also become accidental hosts.

Vector transmission of natural epidemic diseases

One is transmitted by mechanical transport. The most common are intestinal infectious diseases, such as dysentery transmitted by flies and cholera.

Two are worm-borne blood-sucking types, mainly including malaria mosquito, black fever white fly, bubonic plague fleas, epidemic typhus lice, etc.

Three are arboreal sexual transmission, that is, arthropods not only act as a vector for transmitting pathogens, but in most cases arthropods are also hosts for pathogens.

Marmot

Typical natural epidemic disease

Plague

Plague is a natural epidemic disease caused by Yersinia pestis. It is mainly transmitted by human-infected rat flea as a vector, and it causes bubonic plague through the human skin, and pneumonic plague through the respiratory tract. The mortality rate is extremely high.High, is the first legal infectious disease in China, and also the international quarantine infectious disease.

The source of infection and the preservation host are mainly wild rats and other habitual rodents, and weasel and marmot are the most important. They can save Yersinia pestis for winter and cause plague among rats. Although yellow breasted rats and brown house ratsYersinia pestis cannot be stored for a long time. Once they are involved in the plague epidemic among rats, they may become the most direct source of human plague due to their close contact with the human living environment.

The plague is mainly transmitted by fleas, constituting a rodent-flea-human transmission mode; secondly, humans eat skin or flesh of diseased rodents or directly contact the patient's pus or blood or sputum and become infected through skin wounds.The third is that Yersinia pestis in the sputum of patients with pneumonic plague can use human droplets to constitute person-to-person transmission and can cause a plague in the human world.

Anthrax

Anthrax is an animal-borne infectious disease caused by Bacillus anthracis. It is mainly caused by the invasion of Bacillus anthracis from the skin. It is caused by skin necrosis and scorching ulcers and surrounding swelling and toxemia. It can also cause anthrax or intestinal anthraxThe source of infection is mainly herbivorous cattle, horses, sheep, etc., and there is little human-to-human transmission. The transmission route is direct or indirect contact with the skin, hair, meat, bone meal, or smeared bacterial fats of sick animals to cause skinAnthrax; inhalation of spore-laden dust can cause anthrax in the lungs; eating meat with bacteria can cause intestinal anthrax.

Incubation period of skin anthrax is generally 1-3 days, which can be as long as 12 months; lung anthrax can be as short as 12 hours; intestinal anthrax can be as short as 12-18 hours. The occurrence of anthrax has a certain occupational and seasonal nature, and often moreSee herders, farmers, slaughtering and meat processing and fur processing workers, and veterinarians, etc., are more susceptible to infections in the summer due to higher skin exposure.

epidemic hemorrhagic fever

Epidemial hemorrhagic fever is hemorrhagic fever with renal syndrome caused by Hantavirus. Rats are the main source of infection. The clinical manifestations are mainly fever, shock, congestive hemorrhage, and acute renal failure. Humans can be excreted by contact with rodents.It is infected through the respiratory tract, digestive tract, and direct contact. After a pregnant woman is infected, the virus can infect the fetus through the placenta.

Epidemic hemorrhagic fever is typical of regional, seasonal and periodic, mainly distributed in Asia, can occur in all four seasons, but the peak period is from November to May of the following year.

Encephalitis B

JE is abbreviated as "JE", and the source of infection can be humans and animals pork, cattle, sheep, horses and other domestic animals, chickens, ducks, geese and other poultry. The main transmission vector is mosquitoes, mostly in summer.It is epidemic in autumn. Patients are characterized by high fever, disturbance of consciousness, convulsions, pathological reflexes, and meningeal irritation. Patients with severe illness often have central respiratory failure, a higher mortality rate, and severe cases may have sequelae. Most adults with JE infection do notOnset, it is a recessive infection, and it can obtain a relatively long-lasting immunity after infection. Therefore, the diseased population is mainly children under 10 years of age, and the peak period is from July to September each year.

Avian Flu

Most poultry and wild birds can be infected, and the most sensitive are chickens and turkeys, ducks, geese and other water birds are mostly recessive infections. When water birds and dry birds are mixed, it can cause cross-transmission, wildThe waterfowl and the reared waterfowl can be transmitted through the common water body. After infection, humans are mainly fever, sore throat, cough, and can cause rapid failure in some cases, resulting in viral pneumonia, respiratory distress syndrome, and multiple organ failure.Avian influenza has a higher mortality rate than influenza.

Prevention and Control of Natural Epidemic Diseases

First of all, we must understand the natural geographical conditions of natural epidemic sources and the conditions of vector animals. This can play a role in making decisions on the prevention and control of natural epidemic diseases. Therefore, we must establish a complete medical geographic database and provide sufficient information.Data.

Secondly, because the vectors and hosts of natural epidemic diseases depend on a certain geographical landscape, the changes in the environment will change the living conditions of the vectors and hosts and weaken or disappear, so it may be beneficial to reform the environment.Prevention and control of natural epidemic diseases.

Again, strengthen health education for people involved in the epidemic source, so that they understand the types of diseases, hazards, symptoms, vectors, routes of transmission, and seasonal fluctuations of harmful medical animals, and avoid entering the epidemic source during dangerous seasons, andMaster the necessary knowledge of health protection, and carry out vaccination if possible.

In short, make full use of advanced technology and methods to describe the distribution map of natural epidemic diseases in China, and formulate prevention and control measures in combination with the epidemic situation, which will play a significant role in the prevention and control of natural epidemic diseases..

Part of the content of this article comes from the original author of "Knowledge is Power" magazine / Ning Fang, Shen Zhuang Beijing Center for Disease Control and Prevention, Center for Disease Control and Emergency Response reviewer / Li Bin Director of Science Popularization Working Committee of Chinese Society for Cell Biology, Shanghai JiaotongDirector, Institute of Immunology, University Medical College