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Omsk haemorrhagic fever virus
Last reviewed: 23.04.2024
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Omsk hemorrhagic fever is an endemic infectious disease transmitted through the bites of mites of the genus Dermacentor and sometimes by infection with direct and indirect contact with muskrats or water rats. It is registered only in some forest-steppe regions of the Omsk and Novosibirsk regions. The rise in morbidity is observed in May-June, then in September-October. The virus was isolated and studied in 1947 by MP Chumakov. The incubation period is from 2 to 5-7, sometimes up to 10 days. The onset of acute: chills with a temperature of 39-40 ° C, headache, weakness. On the 3rd-4th day, hemorrhagic symptoms develop - a small-dot rash, bleeding (nasal, gastrointestinal, uterine). Bronchitis and pneumonia are also noted. The fever lasts from 5 to 15 days. And usually ends with a recovery, against which a second wave of disease is sometimes observed.
[Immunity
After tobogovirus and flavivirus infections persist for a long time, in some cases, a stable lifelong immunity is formed. In endemic areas, it can form in people as a result of infection infection. The number of people with antibodies to local arboviruses increases with age. On recovery, the antigemagglutinins appear in the blood, on the 6th-7th day, by the end of the 2nd week. Detect complement-binding antibodies, and on the 3-4th week. - virus-neutralizing antibodies, first IgM, then IgG. The peculiarity of tick-borne encephalitis is the duration of production of IgM, which are detected even after 3-6 weeks. After the onset of the disease.
Laboratory Diagnostics of Omsk Hemorrhagic Fever
Virologic, biological and serological methods can be used to diagnose alpha-viral and flavivirus infections. Material from a sick person - blood (during the period of viremia), cerebrospinal fluid (with the development of signs of meningoencephalitis), sectional material (brain tissue) - is used to infect cultures of kidney and fibroblast cells of chick embryos, infection of chicken embryos in the allantoic cavity and intracerebral infection of white mice . In tissue cultures, the virus is detected by the cytopathic effect, plaque formation, hemodysorption and haemagglutination reactions. Viruses are typified in DSC, RTGA, and also by neutralization in mice or in cell culture.
In the serological method, virus-specific antibodies in the patient's paired sera can be detected with the help of RSK, RTGA, as well as neutralization reaction in mice or in cell culture. These reactions are considered positive with a fourfold increase in the antibody titer. By the degree of specificity to the etiological agent, the antibodies are arranged in the following sequence: viral neutralizing, complement-binding, antihemagglutinins (in descending order).
Treatment of Omsk haemorrhagic fever
Specific treatment of Omsk haemorrhagic fever is not developed, limited to the conduct of symptomatic therapy. Data on the use of interferon are contradictory, assessment of its therapeutic effect is difficult due to the small number of observations. Vaccines are used to prevent certain flavivirus infections. For example, in order to prevent spring-summer tick-borne encephalitis, formalin-inoculated culture vaccine from strains "Sofiyin" or "205" is used in Russia. For the treatment and prevention of this disease, gamma globulin, obtained by hyperimmunizing horses, is used. To prevent yellow fever, a live attenuated vaccine from strain 17D grown in a chicken embryo is used.