Author: Zhou Jiadi
Review: Ma Yanxia
Unit: Department of Clinical Laboratory, Affiliated Hospital of Shaanxi University of Traditional Chinese Medicine
During the epidemic in Xi'an in December last year, a very unknown Xi'an "hemorrhagic fever" actually rushed to the first place in the hot search, eating melon netizens have watched, and more rumor-mongers spread that eating strawberries will get blood fever, so that many citizens who do not know the truth are discouraged from strawberries, and an uproar is set off for a while.
What kind of disease is "bleeding fever" that has been rubbed enough to become an "internet celebrity" for a while and sounds strange? How does it make people win? Let me take you to uncover this "hemorrhagic fever case." ”
Epidemiological history
The full name of "hemorrhagic fever" is "renal syndrome hemorrhagic fever", also known as "epidemic hemorrhagic fever", which is a natural epidemic disease caused by hantavirus, and is also a Class B infectious disease stipulated in the Law of the People's Republic of China on the Prevention and Control of Infectious Diseases, which belongs to RNA viruses.
According to incomplete statistics at home and abroad, there are currently more than 170 kinds of vertebrates that can be naturally infected with hantavirus, and 53 species of animals found on the mainland carry this virus, the main host is rodents, and other animals include cats, pigs, dogs and rabbits. On the mainland, haddock rats and brown house rats are the main hosts and sources of infection.
Although patients with renal syndrome haemorrhagic fever carry the virus in their blood and urine in the early days, humans are not the main source of infection. Transmission of the virus is distinctly seasonal, with the largest peak from October to January and the smallest peak from May to July.
2. Transmission routes
The main routes of transmission of hantavirus are as follows:
1. Respiratory transmission: rodents carry the excreta of the virus, such as urine, feces, saliva and other polluted dust to form aerosols, which can infect people through the respiratory tract;
2. Transmission of the digestive tract: eating food contaminated by the excreta of the virus carried by rodents can be infected by the oral cavity;
3. Rat bites or wounds can be infected by contact with rat excrement or blood with viruses;
4. Special transmission route: After pregnant women are infected with the virus, they infect babies through the placenta.
3. Classification and clinical manifestations
Hantavirus mainly causes two acute infectious diseases in the clinic, one is hemorrhagic fever in renal syndrome characterized by fever, bleeding, acute renal impairment and immune dysfunction. The other is a hantavirus pulmonary syndrome characterized by pulmonary infiltrates and pulmonary stromal edema, which rapidly develops into respiratory distress and failure.
Why does being infected with hantavirus through the above channels cause fever, bleeding, kidney damage and even shock?
After hantavirus enters the body, it mainly infects human vascular endothelial cells, causing extensive damage to small blood vessels and capillaries, and increased vascular permeability is the main pathological basis for the clinical manifestations of hemorrhagic fever, and at the same time, it can also stimulate the body to produce a large number of cytokines and chemokines, causing immune damage.
The incubation period of this virus is about 7-14 days, and in addition to fever after infection, the symptoms can be summarized as "three pains, three reds and three points" in simple terms. "Three pains" are headache, low back pain and orbital pain; "three reds" refers to flushing of the face, neck, chest and other parts, with drunken appearance; "three points" is soft palate, armpits, chest and back with scratch-like bleeding.
Fourth, the means of detection
Because the early clinical features of hemorrhagic fever are not obvious, it is easy to delay diagnosis as a cold treatment. So what detection methods can be taken once hemorrhagic fever is suspected? At present, there are several methods used for hantavirus detection, which have different characteristics.
Immunochromatography
It has the advantages of simplicity and inexpensiveness, and is suitable for grass-roots units and on-site testing, but it can only be qualitative, not quantitative;
Immunofluorescence test
The operation is simple, but the result judgment is greatly affected by subjective factors, and the quantitative is not accurate enough;
Microplate
It has high sensitivity and simple operation, which is convenient for daily clinical detection and large-scale serological epidemiological investigation;
PCR detection technology
It has the advantages of being fast, sensitive and specific, and can be used to confirm the diagnosis of the disease.
Immune PCR (Im-PCR) technology
This method uses the specificity of the antigen-antibody reaction and combines the high sensitivity of the PCR amplification reaction, which has been rapidly developed in recent years.
5. The precautionary principle
General: Hantavirus is preventable, controllable and treatable, vaccination against hemorrhagic fever is the most effective way to prevent hemorrhagic fever, followed by rat prevention, rat extermination and personal protection are also the main measures to prevent hemorrhagic fever.
1. When outdoor activities, we should try to avoid places where rats are easy to appear at the water's edge and grassland, and avoid contact with rats and their excretion of pollutants;
2. In key places such as villages, orchards, vegetable gardens, and farms, measures to kill rats and prevent rats can be implemented for a long time; in the wild, try to wear long pants and long shirts and outdoor shoes that do not show their toes to prevent being bitten by rats;
3, vaccination of hemorrhagic fever vaccine is the most effective way for individuals to prevent hemorrhagic fever, high incidence of areas of 16-60 years old people, to actively to the nearest vaccination unit to carry out the whole process of standardized hemorrhagic fever vaccination; in the epidemic area for field adventure, tourism, farming and other activities or there are longer-term outdoor tasks in the wild can be vaccinated in advance to prevent hemorrhagic fever vaccine.
4. The treatment of hemorrhagic fever emphasizes "three early and one", which can significantly reduce the case fatality rate. "Three early" refers to early detection, early diagnosis, early treatment, found fever, headache and other suspected symptoms to go to a regular medical institution as soon as possible, pay attention to bed rest after the onset of the disease, reduce activity, early treatment has a decisive factor in the prognosis of the disease; "one" refers to the nearest standardized medical institution to seek medical treatment, to avoid long-distance transport to aggravate the disease.
From this point of view, hemorrhagic fever is not terrible, the clinical performance keeps in mind the "three reds, three pains and three points", vaccination to prevent, "three mornings and one" remember.
【Reference】
[1] Lian Guosheng,Wang Haibo,Mo Qiuhua,Chen Xinbin,Yang Ze,Lin Jican,Ke Mingjian. A comparative study of the industry standards for three laboratory tests for hantavirus[J].Journal of Aerospace Medicine,2020,31(08):899-902.
Li Jing,Du Hong,Wang Xiaoyan,Wang Pingzhong. Research progress on the pathogenesis of hemorrhagic fever in renal syndrome[J].Infectious Disease Information,2020,33(03):193-197.
[3] ZHANG Guobao,YING Lihong,LEI Yongliang. Research Progress on Hantavirus Detection Technology[J].Chinese Journal of Viral Diseases,2015,5(06):476-480.DOI:10.16505/j.2095-0136.2015.06.007.
Sun Yahui, Xi'an Municipal Center for Disease Control and Prevention. How to avoid infection with epidemic hemorrhagic fever.
Edited by: Yeah Reviewer: Xiao Ran