In recent years, some cases of infectious diseases with fever with thrombocytopenia as the main manifestation were found and reported in Henan, Hubei, Shandong, and Anhui provinces, and a few of the severely ill patients could die due to multiple organ damage and ineffective treatment. In May 2010, the CDC initiated surveillance of fever with thrombocytopenia syndrome cases in some areas of Hubei and Henan provinces. After laboratory tests such as identification of viruses isolated from patients’ blood, whole genome gene sequence analysis, and double serum antibody neutralization tests in the acute and recovery phases, a new virus infection belonging to the Bunyaviridae family was found in most of the case specimens reported in the two provinces, and the fever with thrombocytopenia cases detected were tentatively identified to be related to this new virus infection. Since the naming and further confirmation of the virus is still in progress, the fever with thrombocytopenia syndrome was tentatively named as the disease caused by this virus infection. In order to provide timely guidance to clinicians and disease prevention and control professionals in the diagnosis, reporting, treatment, on-site investigation, laboratory testing, outbreak prevention and control, and public health education of this disease, this technical guide is developed based on the current understanding of the disease and research progress.
I. Purpose
(a) To guide medical institutions at all levels to carry out the diagnosis and treatment of fever with thrombocytopenia syndrome, timely reporting of cases and good personal protection.
(B) guide disease prevention and control agencies at all levels to carry out epidemiological investigation, laboratory testing and epidemic control of fever with thrombocytopenia syndrome.
(C) to guide the prevention of fever with thrombocytopenia syndrome around the public health education work.
Second, the disease overview
(A) Pathogenesis. The newly discovered virus belongs to the Bunyaviridae family (Bunyaviridae) of the genus Phlebovirus, the virus particles are spherical, 80-100 nm in diameter, with a lipid envelope and spines on the surface. The genome contains three single-stranded negative-stranded RNA fragments (L, M and S), the L fragment is 6368 nucleotides long and contains a single read frame encoding an RNA-dependent RNA polymerase; the M fragment is 3378 nucleotides long and contains a single read frame encoding a 1073 amino acid glycoprotein precursor; the S fragment is a bisense RNA and the genome encodes viral proteins in a bidirectional manner. nucleoproteins and nonstructural proteins. The viral genome end sequences are highly conserved and identical to other viral members of the genus Whitefly virus, which can form pot-stalk-like structures.
The virus has about 30% amino acid homology with the Rift Valley fever virus Uukuniemi virus of the genus Bunyaviridae.
Bunyaviridae viruses are weakly resistant, acid intolerant, easily inactivated rapidly by heat, ether, sodium deoxycholate and commonly used disinfectants and UV irradiation.
(II) Epidemiology.
1. Geographical distribution. Cases of the disease have been found in Henan, Hubei, Shandong, Anhui, Liaoning and Jiangsu provinces, and cases are mainly distributed in the rural areas of mountainous and hilly areas in the above provinces and are highly disseminated.
2. Season of onset. The disease mostly occurs in spring and summer, and may vary slightly from region to region.
3.Population distribution. The population is generally susceptible, and residents and workers living and producing in hilly, mountainous and forest areas, as well as tourists who go to such areas for outdoor activities, are at higher risk of infection.
4. Transmission routes. The transmission route is still uncertain. The virus has been isolated from ticks in the areas where the cases were found. Some cases have a clear history of tick bite before the onset of the disease. No evidence of human-to-human transmission has been found. Blood from patients in the acute phase may be infectious.
(iii) Clinical manifestations. The incubation period is not well defined and may be 1 week to 2 weeks. Acute onset, the main clinical manifestations are fever, the body temperature is more than 38 ℃, severe cases continue to high fever, up to 40 ℃ or more, some cases of fever can be up to 10 days or more. In some cases, the fever can last for more than 10 days. It is accompanied by weakness, obvious poor appetite, nausea, vomiting, etc. Some cases have headache, muscle aches, diarrhea, etc. On examination, there are often swollen superficial lymph nodes in the neck and groin with pressure pain, epigastric pressure pain and relatively slow pulse.
A small number of cases are critically ill, with impaired consciousness, skin petechiae, gastrointestinal bleeding, pulmonary hemorrhage, and death due to multiple organ failure including shock, respiratory failure, and diffuse intravascular coagulation (DIC).
The vast majority of patients have a good prognosis, but previous underlying diseases, elderly patients, the presence of psychoneurological symptoms, significant bleeding tendency, hyponatremia, etc. suggest severe disease and a poor prognosis.
Third, diagnosis, treatment and reporting
Medical institutions should follow the Diagnosis and Treatment Plan (Annex 2) and the Chinese Medicine Diagnosis and Treatment Plan (Annex 3) to make good diagnosis and treatment.
When medical institutions at all levels find suspected or confirmed cases that meet the definition of cases, they should temporarily refer to the reporting requirements of Class B infectious diseases for direct reporting through the national disease surveillance information reporting system within 24 hours. The disease category for reporting suspected cases should be “fever with thrombocytopenia syndrome” under “other infectious diseases”; for laboratory-confirmed cases, they should be reported under “fever with thrombocytopenia syndrome For laboratory-confirmed cases, they should be reported or revised under “human novel bunyavirus disease” under the entry of “fever with thrombocytopenia syndrome”.
In line with the “national public health emergencies related information reporting management practices (for trial implementation)” requirements, in accordance with the corresponding provisions of the report.
IV. Laboratory testing
Medical institutions at all levels found suspected cases, should be in accordance with the “laboratory testing program” (Annex 4) requirements, the collection of patients in the acute phase of serum specimens, and laboratory testing. If the diagnosis needs, the local disease prevention and control agencies can assist medical institutions to collect recovery specimens for antibody titer comparison test. Medical institutions that are not equipped for testing should transport the specimens to the local disease prevention and control agency for testing. If the local disease prevention and control agency is not equipped to conduct testing, the specimen should be transported to a higher-level disease prevention and control agency for testing. The CDC should provide timely feedback to the medical institution on the test results.
In the process of specimen collection, transportation and laboratory work, in accordance with the “Pathogenic Microorganisms Laboratory Biosafety Management Regulations” and other relevant provisions, to do a good job of biosafety. Specimen collection can be general protection (wearing masks, gloves and long-sleeved work clothes). After collection, specimens should be sent for examination in leak-proof containers, taking care not to contaminate the appearance of the containers and to disinfect them accordingly. Serology and nucleic acid testing should be carried out in a biosafety level II or higher laboratory.
V. Epidemiological investigation
After receiving the case report, the CDC should immediately organize professional staff to conduct epidemiological investigation in accordance with the Epidemiological Investigation Plan (Annex 5), trace the possible source of infection, investigate the transmission route and related influencing factors, fill out the Epidemiological Case Investigation Form (see Annex 5 attached), and enter it into the EpiData database (downloaded from the website of the Chinese Center for Disease Control and Prevention). The provincial disease prevention and control agencies will collect and summarize the database of the province (district and city) at the end of each month and report to the CDC in a timely manner.
The emergence of aggregated cases should be promptly reported to the higher-level disease prevention and control agencies, and the provincial and above disease prevention and control agencies to organize relevant investigations.
VI. Preventive and control measures
(A) strengthen case management and reduce the risk of transmission. In general there is no need to implement isolation of patients. The patient’s blood, secretions, excretions and the environment and objects contaminated by them can be disinfected by high temperature, high pressure, chlorine-containing disinfectants, etc. When resuscitating or caring for critically ill patients, especially when the patient has hemoptysis, vomiting blood and other bleeding phenomena, medical staff and accompanying personnel should strengthen personal protection and avoid direct contact with the patient’s blood.
(B) carry out training of medical and health professionals at all levels to improve prevention and control capabilities. All areas should carry out training for medical personnel and disease control personnel to improve the ability of medical personnel to detect, identify, report and treat; improve the epidemiological investigation and epidemic disposal capabilities of disease control personnel.
(C) strengthen testing and improve laboratory diagnostic capabilities. When a suspected case is found, specimens should be collected in a timely manner for laboratory testing. The provincial Centers for Disease Control and Prevention should establish laboratory testing capabilities for the disease as soon as possible. Municipalities and county (district) level Centers for Disease Control and Prevention and medical institutions that have or may have outbreaks should also gradually establish laboratory diagnostic capabilities for the disease.
(D) do a good job of public health education and improve knowledge of disease prevention. Actively and widely publicize disease prevention and control and knowledge of ticks and other vector insects, so that the general public can grasp the most basic common sense of prevention and thus consciously protect themselves and take timely and effective preventive measures, so that the public can correctly treat the occurrence of the disease and avoid unnecessary social panic caused by the outbreak. See Annex 6 for the main points of tick prevention and publicity.
(E) Do a good job of vector control and reduce the density of transmission vectors. Measures such as patriotic health campaigns, environmental cleanups, and tick extermination when necessary should be taken to reduce the density of ticks and other vectors in production and living environments.