Crimean hemorrhagic fever


Congo-Crimean hemorrhagic fever /KKHG/or Bulgarian hemorrhagic fever is an acute infectious disease, a tick-borne zoonosis caused by Crimean–Congo hemorrhagic fever virus (CCHFV), assigned to the genus Nairovirus of the Bunyaviridae family.

7 main strains of the virus have been identified based on differences in the genome observed in the different regions of the world where it is prevalent.

On the territory of Europe, the disease has the most natural outbreaks in Bulgaria, with the potentially most endemic areas being Pazardzhik, Shumen and Burgas, the first case of the disease was described in Stara Zagora in 1952 but in 1953 a report was prepared in which a case with similar clinical manifestations was reported in Burgas in 1946.

What are the symptoms?

The onset of CCHG is sudden, about 1-3 days after the tick bite or 3-5 after exposure to infected blood strong>, with the initial signs and symptoms – headache, high fever, back pain, joint pain, stomach pain and vomiting.

The more specific clinical manifestations of the disease are redness of the eyes, face and throat and the appearance of petechiae – blood-red spots on the palate. In more severe cases, patients develop jaundice, and in the most severe cases, changes in mood and sensory perception are observed.

As the disease progresses, frequent profuse nosebleeds and uncontrollable bleeding begin, usually from the site where the blood sample was taken.

These clinical manifestations appear about 3-5 days after the initial ones lasting about 2 weeks. In documented outbreaks, the mortality rate in hospitalized patients ranges from 9 to 50%.

The long-term effects of the disease on the body have not been studied well enough in survivors to be able to determine whether or not specific complications exist. However, recovery is slow.

What are the causes?

Ixodid ticks, and especially those of the Hyalomma species, are a reservoir and vector for the virus that causes CCHG. Many wild and domestic animals such as cattle, goats, sheep and rabbits serve as hosts for the spread of the disease.

Human infection occurs through the bite of infected ticks or contact with contaminated animal blood. The virus can be transmitted from an infected person to a healthy person through contact with contaminated blood or body fluids.

The spread of HCC in hospitals has also been documented due to improper sterilization of medical equipment, reuse of needles, or due to contaminated medical supplies.

Treatment of Crimean hemorrhagic fever

The virus is sensitive in vitro to the antiviral drug ribavirin. In addition to therapy with this medicinal product, maintenance therapy is also applied, carefully observing the balance of fluids in the body and taking timely measures to correct the electrolyte imbalance that occurs as a result of vomiting.

Infusions of glucose, saline solutions, vitamins and platelet mass are performed to stop uncontrollable bleeding. Gammaglobulins are administered, which help the immune system to form faster antibodies against the virus. If necessary, respiratory function is supported with oxygenation and circulation with blood transfusion. If the patient develops a secondary bacterial infection, antibiotics are administered intravenously.


Agricultural workers and all other meat handlers should use insect repellent on exposed skin and clothing. Insect repellents containing DEET (diethyl-meta-toluamide) are most effective at repelling ticks. Wearing gloves and protective clothing is recommended.

In Bulgaria, an inactivated vaccine against Crimean hemorrhagic fever is administered, which leads to the development of protective immunity against the CCHF virus 14 days after its administration. Then a 2nd dose is administered 30-45 days after the initial vaccination. About a year after that, reimmunization is done and then the same procedure is done every 5 years. The vaccine is paid for by the Ministry of Health and is free of charge for all Bulgarian citizens, practicing a profession or carrying out an activity that implies exposure to the risk of infection with the CKHG virus.

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