Laboratory diagnosis of Crimean-Congo hemorrhagic fever virus infections

Crimean-Congo hemorrhagic fever virus is a tick-borne viral zoonosis widely distributed in Africa, Asia, Russia and the Balkans. The emergence and re-emergence of Crimean-Congo hemorrhagic fever virus emphasizes the importance of developing standardized, rapid and sensitive assays. Confirmation of infection in the acute phase of illness is currently achieved by detection of viral nucleic acid in serum samples using reverse transcriptase (RT)-PCR, or by isolation of the virus. RT-PCR has provided a rapid and reliable method for early diagnosis. In addition, real-time RT-PCR can be used to determine viral load, which has application as a prognostic indicator. In convalescent samples collected from nonfatal cases, the diagnosis is confirmed by demonstration of an immune response. Patients with fatal infections almost always do not develop a demonstrable antibody response. Accurate interpretation of laboratory findings is dependent on the kinetics of viremia and antibody responses in humans as well as an accurate history of onset date and clinical pathology.