What are the transmission routes and control points of Ebola hemorrhagic fever and Marburg hemorrhagic fever?

Ebola hemorrhagic fever (EHF) is an acute hemorrhagic infectious disease caused by Ebola virus (EBV). People are infected mainly through contact with body fluids, excreta and secretions of patients or infected animals. The clinical manifestations are mainly fever, bleeding and multiple organ damage. The mortality rate of Ebola hemorrhagic fever is high, reaching 50%-90%. The disease was first discovered in Africa in 1970s, and it is mainly prevalent in Uganda, Congo, Gabon, Sudan, C? te d 'Ivoire, Liberia and South Africa. 2. Transmission route (1) Contact transmission Contact transmission is the main transmission route of this disease. Blood and other body fluids, vomitus, secretions and excretions (such as urine and feces) of patients or animals are highly contagious, and they can be infected by contact with patients and subclinical infected people (especially blood, feces and other pollutants). The patient's blood can maintain a high virus content from acute stage to death, and medical staff are easily infected when treating, caring for patients or disposing of patients' corpses. The referral of patients will also cause the spread between hospitals. Hospital transmission is an important factor leading to the outbreak of Ebola hemorrhagic fever. (2) Aerosol transmission and inhalation of infectious secretions and excreta can also cause infection. From 65438 to 0995, some scholars reported that rhesus monkeys and macaques were used as experimental animals infected with Ebola virus, and droplets containing secretions and excreta of infected animals infected normal monkeys through the air, which confirmed the role of aerosol in the spread of Ebola virus. (3) Injection route In the past, the use of unsterilized syringes was an important way to spread diseases. 1976 a suspected malaria patient in zaire died of Ebola hemorrhagic fever within one week after receiving injection treatment. (4) Sexual transmission: On the 39th day, the 6th1day, or even the 6th 10 1 day, the virus was detected in the semen of an Ebola hemorrhagic fever patient, so there was the possibility of sexual transmission. 3. Population susceptibility and human susceptibility to Ebola virus in the onset season. The incidence is mainly concentrated in adults, mainly because adults have more opportunities to contact patients. There is no data to show that there is a difference in incidence between different sexes. Long-term observation shows that the incidence of Ebola hemorrhagic fever has no obvious seasonality. 4. Geographical distribution In recent decades, Ebola hemorrhagic fever has been mainly prevalent in Uganda, Congo, Gabon, Sudan, C? te d 'Ivoire, Liberia and South Africa in Africa. Seroepidemiological survey data show that there are also cases of Ebola virus infection in Kenya, Liberia, Central Africa, Cameroon and other countries. 1976, a large-scale epidemic of hemorrhagic fever broke out suddenly in the Democratic Republic of Congo and Sudan. In Yanbuku, a small town near Ebola in Congo, there were 3 18 patients and 280 deaths, which were mainly spread in hospitals, hence the name Ebola hemorrhagic fever. At the same time, there were 284 patients in neighboring southern Sudan, with a death rate of 15 1 person. In recent years, the most serious epidemic occurred in 1995, in the Democratic Republic of Congo and the national capital Kuwait. This is a typical epidemic caused by hospital infection. * * * There are 3 15 patients, including 43 medical staff, and the total mortality rate is 8 1%. At present, Ebola hemorrhagic fever patients have not been found in China, but with the increasing international exchanges, the possibility of introducing the disease through animals or through recessive infected people and patients is not ruled out. Ebola virus was detected in monkeys from the Philippines 1989 and the United States 1990, Italy 1992 and the United States 1996. Therefore, we should be vigilant and pay close attention to the changes of foreign epidemic situation. (3) Clinical manifestations. The incubation period of this disease is 2-2 1 day, usually 5- 12 days. After being infected with Ebola virus, it can be asymptomatic or mild, and non-severe patients will gradually recover after 2 weeks of onset. Typical cases are acute onset, with clinical manifestations of high fever, chills, headache, myalgia, nausea, conjunctival congestion and relatively slow pulse. Nausea, vomiting, abdominal pain, diarrhea, sticky stool or bloody stool may occur 2-3 days after onset, and half of patients may have sore throat and cough. 4-5 days after the illness, he entered the climax, continued to have fever and conscious changes, such as delirium and drowsiness. Severe patients may have different degrees of bleeding tendency within a few days after onset, including hemoptysis, nose, mouth, conjunctiva, gastrointestinal tract, vagina and skin bleeding or hematuria. The peak of bleeding is 10 day after illness, and more than 50% patients have severe bleeding, and may die of bleeding, liver and kidney failure and fatal complications. The most obvious manifestations of patients are hypotension, shock and facial edema, and DIC, electrolyte and acid-base imbalance may also occur. 90% of the dead patients died within 12 days after onset (7- 14 days). Acute complications include myocarditis and bacterial pneumonia. Because the virus persists in semen, it can also cause delayed symptoms such as orchitis and testicular atrophy. Measles-like rash may appear on the 5th to 7th day of the course, especially on the shoulders, palms and soles. After a few days, the peeling will subside, and some patients may have skin changes for a long time. (4) Pathological features. The main pathological changes were bleeding of skin, mucosa and organs. Focal necrosis can be seen in many organs, but liver and lymphatic tissue are the most serious. Dotted and focal necrosis of hepatocytes is the most remarkable feature of the disease, including small inclusion bodies and apoptotic bodies. 2. Diagnosis, treatment and reporting It is quite difficult to diagnose Ebola hemorrhagic fever in the early clinical stage. Because its symptoms are not specific, it is not easy to distinguish it from Lassa fever, yellow fever, Marburg hemorrhagic fever, Crimean-Congo hemorrhagic fever, hemorrhagic fever with renal syndrome and other viral hemorrhagic fever. We can refer to the epidemiological characteristics of these diseases, mainly the epidemic areas and seasons. Diagnosis mainly depends on laboratory examination. At present, there is no specific treatment for Ebola hemorrhagic fever, mainly symptomatic and supportive treatment. See the Ebola hemorrhagic fever diagnosis and treatment plan for details. When medical institutions at all levels find suspected or confirmed cases of Ebola hemorrhagic fever that meet the definition of cases, they should refer to the reporting requirements of Class A infectious diseases and report directly through the national disease monitoring information reporting management system, and choose "other infectious diseases" as the reporting category. In accordance with the requirements of the "National Public Health Emergencies Related Information Reporting Management Standard (Trial)", the report shall be made in accordance with the corresponding regulations. Third, the following laboratory results can be diagnosed: virus antigen is positive; Serum specific IgM antibody was positive; The titer of serum specific IgG antibody in recovery period is more than 4 times higher than that in acute period. Ebola virus RNA was detected from patient specimens; Ebola virus was isolated from patient specimens. (1) serological detection. Patients can detect specific IgM and IgG antibodies from serum as early as 7- 10 days after symptoms appear. IgM antibody can be maintained for 3 months and IgG antibody can be maintained for a long time. Most patients' antibodies appeared on 10- 14 days after onset, and some critically ill patients failed to detect antibodies until their death. Therefore, IgG antibody detection is mainly used for seroepidemiological investigation, and IgM antibody can be used as an index for seroepidemiological investigation of recent infection, but it can not meet the needs of early diagnosis. Serum specific IgM antibodies were mostly detected by IgM capture ELISA. Serum-specific IgG antibodies are mostly detected by ELISA and immunofluorescence. (2) Pathogen detection. Ebola virus is highly dangerous, and experiments related to live virus must be carried out in BSL-4 laboratory. 1. Detection of virus antigen: Because of the high viremia titer of Ebola hemorrhagic fever, ELISA and other methods can be used to detect virus antigen in serum. Immunofluorescence is also widely used, which can detect virus antigens from the liver and spleen of infected animals. 2. Nucleic acid detection: RT-PCR and other nucleic acid amplification methods were used for detection. Generally, viral nucleic acids can be detected in patients' serum within one week after onset. 3. Virus isolation: Collect serum samples of patients within one week of onset, and use Vero cells for virus isolation and culture. Four. Prevention and control measures At present, there is no vaccine to prevent Ebola hemorrhagic fever. Controlling the source of infection is the most important measure to prevent and control Ebola hemorrhagic fever. (1) Preventive measures. 1. Strengthening the surveillance of imported Ebola hemorrhagic fever and finding and isolating imported cases in time are the keys to effectively control the source of infection. Health departments should strengthen joint defense with inspection and quarantine, tourism, transportation and other departments to find imported cases from epidemic areas in time. Strengthen animal quarantine, especially non-human primates such as chimpanzees, gorillas and monkeys and wild animals such as bats. Animals imported from abroad, especially from Ebola hemorrhagic fever epidemic areas, should be strictly quarantined. Once the port quarantine department finds suspicious cases and animals, it shall promptly notify the health department to investigate and deal with the epidemic situation. 2. Educate tourists and medical and health workers who go to epidemic areas in Africa about disease prevention to avoid contact with primates in the jungle. When contacting patients in the hospital, we should be vigilant and do personal protection. 3. Pay close attention to the epidemic dynamics of Ebola hemorrhagic fever, strengthen international information exchange and cooperation, especially pay close attention to the epidemic situation in Uganda, Congo, Gabon, Sudan, C? te d 'Ivoire, Liberia, South Africa and other areas where Ebola hemorrhagic fever has been prevalent in Africa. (2) Epidemic control measures. 1. Case and contact management Medical institutions at all levels should report suspected cases of Ebola hemorrhagic fever in time, so that health administration and disease control departments can grasp the epidemic situation as soon as possible and take necessary prevention and control measures. Once suspicious cases and their contacts are found, strict isolation measures should be taken to control the source of infection and prevent the spread of the epidemic. 2. Do a good job in hospital infection control (1) Strengthen personal protection. Because contact with pollutants is the main mode of transmission, you should wear masks, gloves, glasses, hats and protective clothing when contacting patients to prevent direct contact with pollutants from patients. If there is a lot of blood, body fluids, secretions and excretions in the environment, you should also wear leg covers and shoe covers. When you leave the ward, you should take off all the isolation suits. The shoes are polluted and need to be cleaned and disinfected. To prevent skin damage when handling sharp instruments such as needles, you should consult the epidemic prevention department or infection department if you are undergoing surgical or obstetric treatment. (2) Strictly disinfect the patient's excreta and contaminated articles, and strictly disinfect the patient's secretions and excreta, which can be treated by chemical methods; Infectious medical pollutants (contaminated needles, syringes, etc. ) can be incinerated or autoclaved. When people's skin and mucous membranes come into contact with the body fluids, secretions or excretions of suspected Ebola hemorrhagic fever patients, they should be washed immediately with soapy water or with appropriate disinfectants; Wash mucosa with plenty of water or eye drops, and evaluate and follow up the contacts. Doing a good job of disinfection and isolation in hospital to prevent nosocomial infection is an important link to prevent Ebola hemorrhagic fever. One person, one needle, one tube, one sterile or disposable syringe should be adhered to. After the death of the patient, the disposal and transport of the corpse should be minimized. After disinfection, the corpse should be wrapped in sealed and leak-proof articles, burned in time or buried nearby. When transfer treatment is needed, it should also be carried out in a sealed container. When autopsy is needed, disinfection and isolation measures should be strictly implemented. Clothes worn by patients should be disinfected or burned with steam. 3. Strengthening Laboratory Biosafety All experimental activities involving Ebola virus should be carried out in strict accordance with relevant regulations of China. Relevant laboratory tests should be reduced to the minimum requirements. Personal protection should be paid attention to when collecting specimens. The collected specimens should be put into plastic bags, then put into strong leak-proof containers with good marks and sent directly to the laboratory. Be careful not to pollute the appearance of the container and disinfect it accordingly. The inspection laboratory should have the corresponding biosafety level. Virus isolation and culture can only be carried out in BSL-4 laboratory. 4. Epidemiological investigation After receiving the case report, the disease control personnel should immediately carry out epidemiological investigation, including investigating the activity history during the onset of the case, looking for close contacts and co-exposed persons, looking for the source of infection, isolating and controlling the source of infection in time to prevent the spread of the epidemic. 5. Carry out public publicity and education, correctly prevent and reduce panic, actively and widely publicize the knowledge of Ebola hemorrhagic fever prevention and control, and avoid unnecessary social panic after the outbreak. Make the public treat the incident correctly and take timely and effective preventive measures. The diagnosis and treatment of Ebola hemorrhagic fever and controlling the source of infection are the most important measures to prevent and control Marburg hemorrhagic fever, so it is necessary to strengthen frontier health quarantine to prevent the disease from being introduced into China. (1) Preventive measures. 1. Strengthen the surveillance of imported Marburg hemorrhagic fever. Inspection and quarantine institutions should strictly take quarantine measures against people from epidemic areas, strengthen health declaration, temperature detection and medical examination, and implement necessary isolation measures for suspicious cases found. Those with definite exposure history should be observed for 2 1 day, checked and treated, and their body temperature should be monitored daily. And immediately notify the local health department to carry out patient treatment and epidemic investigation and handling. It is necessary to strengthen the quarantine of imported animals, especially non-human primates imported from epidemic areas. 2 to carry out health education for tourists and medical staff in epidemic areas. Travelers to Marburg hemorrhagic fever epidemic areas should have basic knowledge of disease prevention and avoid close contact with poisonous primates and patients. Medical staff working in medical and health institutions in epidemic areas should fully understand the epidemic situation and disease prevention knowledge, avoid contact with primates, and take necessary personal protective measures when contacting suspicious patients. People who leave the epidemic area should seek medical treatment immediately if they develop fever within 2 1 day after departure, and inform the doctor of their travel history in the epidemic area. 3. Pay close attention to the epidemic dynamics of Marburg hemorrhagic fever. Health departments and quarantine departments should be vigilant, pay close attention to the changes of foreign epidemic situation, especially in African countries, and grasp the dynamic information of epidemic situation in time. (2) Epidemic control measures. Medical institutions at all levels should immediately report suspected cases of Marburg hemorrhagic fever to the local centers for disease control and prevention, so that the health administration and disease control departments can grasp the epidemic situation as soon as possible and take necessary prevention and control measures. 1. Case and contact management. Suspected cases and their contacts should be observed on the spot. Confirmed cases must be strictly isolated in infectious disease specialized hospitals, and respiratory protection measures should be taken in isolated areas. Male patients must be forbidden to have sex for at least 3 months until sperm tests are virus-free. 2. Prevent hospital infection (1) and strengthen personal protection. All staff who contact, care for infected animals and cases and deal with epidemic spots must wear full protective clothing and gas masks to operate. (2) Strictly and thoroughly disinfect the patient's excreta and contaminated articles, including the patient's excreta, secretions, blood and all articles that the patient has contacted, as well as blood test instruments and suspected contaminated places. Sensitive disinfectants should be used for spraying, spraying or fumigation. Commonly used disinfectants are 0.5% sodium hypochlorite solution, peracetic acid, formalin or carbonic acid plus detergent, etc. Other methods include autoclaving, incineration or boiling, and ultraviolet rays can also be used for air disinfection. After the death of the patient, the handling and transshipment of the body should be minimized, and the body should be wrapped with sealed and leak-proof articles, burned in time or buried nearby. When transfer treatment is needed, it should also be carried out in a sealed container. When autopsy is needed, disinfection and isolation measures should be strictly implemented. Clothes worn by patients should be disinfected or burned with steam. 3. Strengthen laboratory biological safety All operations involving live Marburg virus must be carried out in BSL-4 laboratory. Laboratory inspection should be carried out in the biosafety cabinet. If there is no biosafety level 3 or above detection conditions, the number of inspections should be reduced as much as possible, and personal protection should be done during operation. 4. The incubation period of epidemiological investigation of the disease can be as short as three days, and it is necessary to carry out contact follow-up investigation quickly. All persons who may be in close contact with the patient during the infection period shall be observed in isolation: the body temperature shall be measured twice a day until three weeks after the last contact, and once the body temperature is higher than 38.3℃, isolation treatment shall be carried out immediately. All animals in contact with patients should be registered, tracked, isolated and observed. 5. Carry out public publicity and education, correctly prevent and reduce panic, actively and widely publicize Marburg hemorrhagic fever prevention and control knowledge, and avoid unnecessary social panic after the outbreak. Make the public treat the incident correctly and take timely and effective preventive measures.