Ebola Hemorrhagic Fever (EHF) is an acute hemorrhagic infectious disease caused by the Ebola virus (Ebolavirus). People are infected mainly through contact with body fluids, secretions and excretions of patients or infected animals, and the clinical manifestations are mainly sudden onset of fever, hemorrhage and multi-organ damage. Ebola hemorrhagic fever has a high mortality rate of 50%-90%. The disease was first discovered in Africa in 1976 and is now prevalent mainly in Uganda, Congo, Gabon, Sudan, Cote d’Ivoire, South Africa, Guinea, Liberia, Sierra Leone and other African countries.
I. Diagnosis, treatment and reporting
The early clinical symptoms of Ebola hemorrhagic fever are not specific and should be distinguished from other viral hemorrhagic fevers such as Lassa fever, yellow fever, Marburg hemorrhagic fever, Crimean-Congo hemorrhagic fever, and renal syndrome hemorrhagic fever. Definitive diagnosis relies mainly on laboratory tests. There is no specific treatment for Ebola hemorrhagic fever, but mainly symptomatic and supportive treatment.
When medical institutions at all levels find suspected or confirmed cases of Ebola hemorrhagic fever that meet the case definition, they should report directly through the network within 2 hours via the national disease surveillance information reporting management system, and select “Ebola hemorrhagic fever” in the category of “other infectious diseases”. “. In accordance with the requirements of the “National Public Health Emergencies Information Reporting Management (Trial)” for reporting public health emergencies or related information.
Second, laboratory testing
1, pathogenetic testing
(1) viral antigen detection: as Ebola hemorrhagic fever has high titer viraemia, ELISA and other methods can be used to detect viral antigen in blood specimens. Generally, virus-specific antigens can be detected in the patient’s blood specimens within 2-3 weeks after the onset of the disease. Immunofluorescence and immunohistochemistry can be used to detect viral antigens in animal and suspected case autopsy specimens.
(2) Nucleic acid detection: RT-PCR and other nucleic acid amplification methods are used for detection. Viral nucleic acid can generally be detected in blood specimens from patients within 2 weeks after the onset of the disease, and the detection rate is high for specimens within 1 week after the onset of the disease.
3, (3) High rate of virus isolation.
2.Serological detection
According to the literature, specific IgM antibodies can be detected from the sera of patients as early as 2 days after the onset of the disease, and IgM antibodies can be maintained for several months. IgG antibodies can be detected 7-10 days after the onset of the disease, and IgG antibodies can be maintained for several years. In most patients, antibodies appear 10-14 days after the onset of disease, but in some severe cases, antibodies are never detected. A positive IgM antibody or a 4-fold or higher IgG antibody titer in two blood specimens taken 1 week or more apart is diagnostic.
Serum-specific IgM antibodies are mostly detected by IgM capture ELISA; serum-specific IgG antibodies are mostly detected by ELISA, immunofluorescence and other methods.
III. Prevention and control measures
At present, there is no vaccine to prevent Ebola hemorrhagic fever, isolation and control of infectious sources and strengthen personal protection is the key measures to prevent and control Ebola hemorrhagic fever.
1, case and contact management.
Once a suspected case is found, strict isolation measures should be taken to control the source of infection and prevent the spread of the epidemic.
Close contacts are those who may come into contact with the patient’s blood, secretions, excretions, etc. after the onset of the disease, such as those who accompany, treat, transfer the patient and dispose of the body. Close contacts are tracked and medically observed. The period of medical observation is 21 days from the date of last exposure. Once clinical symptoms such as fever, malaise and sore throat appear during medical observation, isolation should be carried out immediately and specimens should be collected for testing.
After the death of a patient, the handling and transfer of the body should be minimized. The corpse should be disinfected and wrapped with sealed leak-proof items and promptly incinerated or disposed of according to relevant regulations. When an autopsy is required, it should be performed in accordance with the “Regulations for Autopsy Inspection of Patients with Infectious Diseases or Suspected Infectious Diseases”.
2.Infection control in the hospital.
In accordance with the requirements of the “Hospital Infection Management Code” to do a good job in the hospital infection control.
(1) Strengthen personal protection.
On the basis of standard protection, contact protection and respiratory protection should be done.
(2) Strict disinfection of patients’ secretions, excretions and their contaminated items.
Patient’s secretions and excretions need to be strictly disinfected and can be treated chemically; infectious medical dirt (contaminated needles, syringes, etc.) can be treated by incineration or high-pressure steam disinfection.
Human skin exposed to suspected Ebola hemorrhagic fever patient’s body fluids, secretions or excretions should be immediately washed thoroughly with water or soapy water, or disinfected with 0.5% iodophor disinfectant, 75% alcohol chlorhexidine wipe, use water or soapy water to thoroughly clean; mucous membranes should be rinsed with large amounts of water or 0.05% iodophor.
3, strengthen laboratory biosafety.
All experimental activities involving Ebola virus should be carried out in strict accordance with the relevant provisions of China’s laboratory biosafety.
Specimens should be collected for personal protection. Specimens should be placed in accordance with the ICAO Class A packaging and transport materials, in accordance with the “highly pathogenic microorganisms that can infect humans (virulent) strains or samples transport management regulations” requirements for transport to laboratories with Ebola virus-related experimental activities.
Laboratories conducting relevant experimental activities should have the appropriate biosafety level and experimental activities qualification. The corresponding experimental activities required biosafety laboratory level should be in line with the provisions of the “List of pathogenic microorganisms transmitted on earth”, virus culture in the BSL-4 laboratory, animal infection experiments in the ABSL-4 laboratory, the operation of uncultured infectious material in the BSL-3 laboratory, the operation of inactivated material in the BSL-2 laboratory, the operation of non-infectious material in the BSL-1 laboratory.
4.Epidemiological investigation
It mainly includes investigating the activity history of the case during the onset of the disease, searching for close contacts and co-exposed persons, and searching for the source of infection.
5.Public awareness and education, good risk communication
Actively publicize the prevention and treatment of Ebola hemorrhagic fever and raise public awareness of self-protection. Respond to social concerns in a timely manner.