Middle East DVEP - Armed Forces Pest Management Board

Military Impact and Historical Perspective. Descriptions of a disease compatible withCCHF can be traced back to antiquity in eastern Europe and Asia. CCHF was firstdescribed in soldiers and peasants bitten by ticks of the genus Hyalomma while workingand sleeping outdoors in the Crimean peninsula in 1944. The virus was first isolated in1967. Since there are no available treatment regimens of proven value and recovery fromCCHF can be very protracted, military personnel with CCHF would require significantmedical resources.Disease Distribution. CCHF virus is enzootic in the steppe, savanna, semi-desert andfoothill environments of eastern and central Europe, Russia, parts of Asia, and throughoutAfrica. Several Eurasian epidemics have taken a great toll on human life. In recentyears, cases of CCHF have tended to be sporadic, with most reported from Bulgaria andSouth Africa. CCHF is underdiagnosed in many countries due to lack of appropriatemedical and laboratory services. In most countries surveyed, the prevalence of humanantibodies to CCHF virus in rural areas ranges from 0.1 to 2%. CCHF virus iswidespread in the Middle East, infecting domestic animals everywhere except the islandof Cyprus. Movement of domestic animals between countries in the region is commonand can easily spread the disease. Human outbreaks of CCHF have occurred in Kuwait,Iraq, and the United Arab Emirates. In Iraq there were 63 cases with 41 deaths reportedfrom 1979 to 1981. Over 50% of Iraqi goat, sheep, and horse sera were positive forantibodies, and in another serosurvey 29% of all animal breeders tested in Iraq werepositive. In 1990, seven cases of CCHF occurred in Mecca in western Saudi Arabia. Asubsequent serological survey of abattoir workers in 12 facilities in Saudi Arabiaidentified 40 confirmed or suspected human cases of CCHF between 1989 and 1990, with12 fatalities. Thirteen species of ixodid ticks were collected from livestock. Camels hadthe highest rate of infestation, and Hyalomma dromedarii was the most common tickcollected.Transmission Cycle(s). CCHF virus has been isolated from at least 30 species of ticks.From experimental evidence it appears that many species of ticks are capable oftransmitting the virus, but members of the genus Hyalomma are the most efficientvectors. The aggressive host-seeking behavior of adult hyalommines makes these ticksideal vectors. The highest prevalence of antibodies in wild and domestic reservoirs hasbeen found in arid areas where Hyalomma ticks are common. Antibodies to CCHF virusare widespread in large wild and domestic herbivores. Domestic ruminants generallyacquire infection early in life. Viremia in livestock is short-lived and of low intensity.Antibodies or virus have been found in a variety of small mammals, including hares,hedgehogs and rodents. Transovarial transmission of virus in vector ticks is an importantreservoir mechanism.Humans acquire CCHF virus from tick bites, from contamination of broken skin ormucous membranes with crushed tissues or feces of infected ticks, or from contact withblood or other tissues of infected animals. CCHF virus is highly infectious, andnosocomial infection of medical workers has been important in many outbreaks.85