Crimean-Congo hemorrhagic fever

Abstract

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease caused by the arbovirus Crimean-Congo hemorrhagic fever virus (CCHFV), which is a member of the Nairovirus genus (family Bunyaviridae). CCHF was first recognized during a large outbreak among agricultural workers in the mid-1940s in the Crimean peninsula. The disease now occurs sporadically throughout much of Africa, Asia, and Europe and results in an approximately 30% fatality rate. After a short incubation period, CCHF is characterized by a sudden onset of high fever, chills, severe headache, dizziness, back, and abdominal pains. Additional symptoms can include nausea, vomiting, diarrhea, neuropsychiatric, and cardiovascular changes. In severe cases, hemorrhagic manifestations, ranging from petechiae to large areas of ecchymosis, develop. Numerous genera of ixodid ticks serve both as vector and reservoir for CCHFV; however, ticks in the genus Hyalomma are particularly important to the ecology of this virus. In fact, occurrence of CCHF closely approximates the known world distribution of Hyalomma spp. ticks. Therefore, exposure to these ticks represents a major risk factor for contracting disease; however, other important risk factors are known and are discussed in this review. In recent years, major advances in the molecular detection of CCHFV, particularly the use of real-time reverse transcription-polymerase chain reaction (RT-PCR), in clinical and tick samples have allowed for both rapid diagnosis of disease and molecular epidemiology studies. Treatment options for CCHF are limited. Immunotherapy and ribavirin have been tried with varying degrees of success during sporadic outbreaks of disease, but no case-controlled trials have been conducted. Consequently, there is currently no antiviral treatment for CCHF approved by the U.S. Food and Drug Administration (FDA). However, renewed interested in CCHFV, as well as increased knowledge of its basic biology, may lead to improved therapies in the future. This article reviews the history, epidemiology, ecology, clinical features, pathogenesis, diagnosis, and treatment of CCHF. In addition, recent advances in the molecular biology of CCHFV are presented, and issues related to its possible use as a bioterrorism agent are discussed.