Recently, the new crown pneumonia epidemic in Xi'an has begun to rekindle, and the number of new local confirmed cases has continued to rise, with 63 new cases and 229 existing confirmed cases as of December 23. Under the precarious situation, Xi'an has reported a number of patients with hemorrhagic fever, and the hemorrhagic fever epidemic has made the severe prevention and control situation worse. What is hemorrhagic fever, a very old-sounding and historically proven infectious disease? Will it be passed on from person to person? If unfortunately infected, how will the patient be treated?
Source: China News Network
Bleeding fever is easily mistaken for a cold, and when severe, it can be life-threatening
3D image of Hantavirus. Source: Scientific Animations
Hemorrhagic fever, also known as renal syndrome hemorrhagic fever (HFRS), is an important infectious disease that endangers human health and is caused by the epidemic haemorrhagic fever virus, hantavirus. Hantavirus belongs to the Buniaviridae family, is a negative stranded RNA virus with envelope segments, and the genome includes L, M, and S fragments, encoding L polymerase protein, G1 and G2 glycoprotein, and nuclear protein, respectively. Renal syndrome hemorrhagic fever is a natural epidemic disease caused by hantavirus, and one of the viral diseases that seriously endanger the health of our people, which is a Class B infectious disease stipulated in the Law of the People's Republic of China on the Prevention and Control of Infectious Diseases. Because many people do not understand hemorrhagic fever, they will mistakenly think that they have a cold in the early stage, thus delaying the disease.
pathogen
01
Host animals and sources of infection
It is mainly small rodents, including wild rats and house mice.
02
Route of transmission
Mainly transmitted to animal origin, the virus can be excreted through the blood and saliva, urine and stool of the host animal, and the direct transmission from rats to humans is an important way of human infection.
03
Crowd susceptibility
It is generally believed that the population is generally susceptible, the rate of hidden infection is low, the incidence of young adults is high, and there is lasting immunity after illness.
Clinical manifestations
Clinical manifestations: the incubation period of hemorrhagic fever is generally 2 to 3 weeks. Typical clinical processes are divided into five stages: fever, hypotensive shock, oliguria, polyuria, and recovery.
1. Fever period
Presents predominantly as symptoms due to infectious viremia and systemic capillary damage.
Onset is acute, there are fever (38 ° C ~ 40 ° C), three pains (headache, low back pain, orbital pain) and nausea, vomiting, chest tightness, abdominal pain, diarrhea, general joint pain and other symptoms, skin and mucous membranes three red (face, neck and upper chest redness), eye conjunctival hyperemia, heavy like drunken appearance. Bleeding spots or bruises of varying sizes appear in the oral mucosa, chest, back, and armpits, or in the form of cord-shaped, scratch-like bleeding spots.
2. Hypotensive shock period
Mostly in the 4 to 6 days of fever, when the body temperature begins to drop or shortly after the fever, it is mainly a manifestation of plasma hypovolemic shock. Patients develop hypotension and in severe cases shock occurs.
3. Oliguria period
Urine output is less than 400 ml in 24 hours, and there is often no clear boundary between the oliguria period and the hypotensive period.
4. Polyuria period
Renal tissue damage gradually repairs, but urine output increases significantly because tubular resorption has not been fully restored. It is more common on the 8th to 12th, lasting 7 to 14 days, and the urine output is about 4000 to 6000 ml per day, which is very easy to cause dehydration and electrolyte disorders.
5. Recovery period
With the gradual recovery of kidney function, when the urine output decreases to less than 3000 ml, it enters the recovery period. Urine output and symptoms gradually return to normal, and it takes several months to recover.
In patients with common cold and fever, their physical condition will improve greatly after the fever has subsided, while the condition of patients with hemorrhagic fever may be more serious after the fever is reduced. When the symptoms of the above clinical manifestations appear, we must not take cold medicine at will, and at the beginning of the disease, we must seek medical treatment in time to confirm whether the symptoms are hemorrhagic fever, otherwise we will make mistakes in our own judgment, delay the condition or have a fatal risk.
China was once the main endemic area of haemorrhagic fever
China was once one of the main epidemic areas of epidemic haemorrhagic fever, and in the 1980s, the highest annual reported incidence of hemorrhagic fever in China exceeded 100,000 cases, and hemorrhagic fever was listed as one of the key infectious diseases in the country. The number of reported cases in China accounts for about 80% of the total number of cases in the world, and the incidence of disease is higher in Shaanxi, the three northeastern provinces, Shandong, Hebei, Hunan and other provinces. In recent years, with the improvement of domestic medical standards, human living conditions and natural environment, the risk of inter-rat virus transmission and human exposure has been greatly reduced, and the epidemic of infectious diseases with hemorrhagic fever has decreased significantly, but there are still cyclical fluctuations in a few areas. According to Sun Yaping, an expert at the Xi'an Municipal Center for Disease Control and Prevention, due to the comprehensive effects of climate, terrain, rivers, vegetation and other factors, haddock rats are more common in the Guanzhong area of Shaanxi Province, and the rate of haddock rats carrying hantavirus in the wild is high. Together, the number of cases reported annually in Xi'an, Weinan, Xianyang, Baoji and Yangling demonstration areas in Guanzhong accounts for about 95% of the total number of cases in the province. The incidence is mainly rural residents, accounting for about 80% of the total cases.
"Time Series Analysis of the Incidence of Hemorrhagic Fever in Renal Syndrome in China from 2005 to 2019" Source: Nature
The renal syndrome haemorrhagic fever incidence series is broken down into three parts: (A) the sequence actually observed; (B) trends; (C) seasonal variations; and (D) irregular components.
The results of the analysis showed that the incidence of hemorrhagic fever in renal syndrome had a strong seasonality, with a bimodal pattern, with spring and autumn and winter being the two peaks of incidence, and autumn and winter being much higher than in spring. A strong peak was observed from November to January, while a weak peak was observed in May and June of each year. The observations dovetail with the reported results for much of China, and this significant difference in seasonal behavior is largely influenced by climatic and demographic factors in northern hemisphere cities. In China, the double-peaked activity of the incidence of hemorrhagic fever in renal syndrome may be mainly influenced by its etiology and climatic factors. Earlier studies found that hantavirus-associated renal syndrome hemorrhagic fever infection was reported throughout the year, but most occurred in autumn and winter, while Seoul virus (SEOV)-related cases were usually observed in the spring, and the two pathogens were mainly made up of rodents such as haddocks and brown house mice. It is worth noting that climate drivers, such as temperature, relative humidity, precipitation, etc., affect the reproduction of the host, which can lead to the spread of hemorrhagic fever.
Does hemorrhagic fever be transmitted from person to person?
"Haemorrhagic fever is not a respiratory infectious disease like SARS or influenza A, it is not transmitted from person to person, it is mainly transmitted through contact after contamination with rodent secretions or excrement, so there will be no large-scale leapfrog infection." Song Rui, chief physician of the Infectious Disease Diagnosis and Treatment Center of Beijing Ditan Hospital, analyzed.
According to the information released by Xi'an Disease Control, the mortality rate of hemorrhagic fever is very high, and it is possible to infect hemorrhagic fever if it is bitten by rats, or eat food and water that rats crawl through, and come into contact with blood, urine, feces, etc. of mice with the virus. The population is generally susceptible to infection, and the incidence of rural residents who often cultivate in the wild, or workers engaged in food and agricultural processing, and students majoring in agronomy is extremely high.
Patients with severe disease due to acute and rapid progression of hemorrhagic fever have a certain risk of mortality rate. If the patient is not diagnosed and treated in time, it can even be life-threatening. In terms of contagiousness, the disease is generally sporadic, rarely clustered, and there is little risk of transmission in direct contact with the population. Severe illness of hemorrhagic fever can lead to acute renal failure, and such patients need dialysis to combat the disease, and such severe patients do not transmit other people through the respiratory tract, so dialysis does not require separate isolation.
How can I prevent hemorrhagic fever infections?
Epidemic haemorrhagic fever is a preventable infectious disease that can be avoided by the virus as long as preventive measures are in place. Rodent control and rat prevention are the key to preventing epidemic hemorrhagic fever. If suspicious symptoms such as high fever, three reds, and three pains appear, if there is a history of contact with rodents within 1 month before the onset of the disease, it should be treated as soon as possible, and early detection, early rest, and early treatment can significantly reduce the incidence of severe illness and death.
1. Control the source of infection: strengthen the extermination and prevention of rats in epidemic areas and new development zones.
2. Cut off the transmission route: strengthen personal protection when working in the field, clearing weed straw and field activities. Prevention of inhaled rodent excretion of pollutants and rodent parasites.
3. Protect susceptible people: Vaccination against hemorrhagic fever is one of the most effective measures to prevent hemorrhagic fever. It is recommended that residents of endemic areas and people of foreign age be vaccinated against haemorrhagic fever. The hemorrhagic fever vaccine is given in a total of 3 doses, with the first two injections being spaced 14 days apart and the third dose one year apart. The first two doses of basic immunization are crucial, and it is important to ensure that at least the basic vaccination is completed to obtain a certain immunity. If more than one year after the completion of the basic immunization, the third injection can be revaccinated at any time.
Vaccine immunization effect
Postimmunized neutralizing antibody positive rate: 46% for 2 needles, 96% for 3 injections, preferably 3 injections. Epidemiological effect observation, its protection rate can reach about 90%.
Reaction to vaccination: no response or mild response after injection, low response rate, fever in a small number, or rash. Body temperature is average
Contraindications: fever and acute and chronic infectious diseases. Suffering from severe liver and kidney diseases. Chronic cardiovascular disease. People with a history of allergies.
4. Strengthen epidemic monitoring: do a good job of monitoring the density of rats, the rate of rat-borne viruses, and susceptible populations.
End
Resources:
[1]https://baike.baidu.com/item/%E5%87%BA%E8%A1%80%E7%83%AD/10370582?fr=aladdin
[3]https://baike.baidu.com/item/%E6%B5%81%E8%A1%8C%E6%80%A7%E5%87%BA%E8%A1%80%E7%83%AD%E7%96%AB%E8%8B%97/9373661?fr=aladdin