Crimean-Congo Hemorrhagic Fever: An Endemic Sporadic Zoonotic Viral Infection in Uganda

Abstract

Background and AimCrimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonotic disease caused by Crimean Congo hemorrhagic fever virus (CCHFV), a member of the genus Nairovirus in the family Bunyaviridae and order Bunyavirales. CCHF is typically asymptomatic in animals but can be highly fatal in humans approaching case fatality rate of approximately 30%. The disease is distributed in many countries of Asia, Africa, the Middle East and south-eastern Europe. As the distribution of CCHFV coincides with the distribution of its main vector, Ixodid (hard) ticks of the genus Hyalomma, both a reservoir and a vector for the CCHF virus; the spread of infected ticks into new, unaffected areas facilitates the spread of the virus. Numerous wild and domestic animals, such as cattle, goats, sheep and hares, serve as amplifying hosts for the virus. Transmission to humans occurs through contact with infected ticks or animal blood. CCHF can be transmitted from one infected human to another by contact with infectious blood or body fluids. Documented spread of CCHF has also occurred in hospitals due to improper sterilization of medical equipment, reuse of injection needles, and contamination of medical supplies. Occupational groups with an elevated risk of Crimean Congo hemorrhagic fever include farmers, shepherds, veterinarians, abattoir workers, healthcare personnel and laboratory workers, as well as anyone at elevated risk of exposure to ticks. Seasonality can result from seasonal changes in tick numbers or increased human exposure to slaughtered livestock. The case fatality rate is thought to be approximately 5-30% in most instances, although rates as high as 80% have been reported occasionally in limited outbreaks. Factors such as the availability and quality of healthcare, virus dose, route of exposure, coinfections, and possibly the viral strain, are thought to influence mortality.