Crimean hemorrhagic fever (CHF) was described as a clinical entity in 1944 and 1945 during an epidemic in the western steppe region of Crimea, U.S.S.R. A viral etiology was suggested by reproducing a similar disease syndrome in psychiatric patients undergoing pyrogenic therapy after inoculation with a filterable agent from the blood of CHF patients. CHF virus was shown to be antigenically indistinguishable from Congo virus,originally isolated in 1956 from a febrile patient in Belgian Congo. An excellent description of the history of Crimean-Congo hemorrhagic fever (CCHF) epidemics/outbreaks prior to 1980 was presented in a comprehensive review of the epidemiology of Crimean-Congo hemorrhagic fever (CCHF) virus. The CCHF outbreaks in Astrakhan Oblast were paralleled by a series of outbreaks that began during 1953 in Bulgaria. CCHF cases were more commonly recognized among dairy and farm workers, housewives, school children, and unclassified employees.