Ecology and Epidemiology of Crimean-Congo Hemorrhagic Fever Virus Transmission inthe Republic of Senegal

摘要

Further progress is reported for the third year of a project to study thetransmission ecology of tick borne Crimean Congo Hemorrhagic Fever (CCHF) virus in the West African savannah. Prospective observations in northern Senegal were continued to describe the seasonal activity of potential vector ticks. Adult tick abundance was low relative to previous years and immature ticks feeding on small mammals and birds were most abundant during or after the rainy season. Seroconversion of sheep diminished in concert with decreased tick abundance. Laboratory studies on the feeding of immature Hyalomma truncatum and H. marginatum rufipes demonstrated that the feeding pattern ( 2-or 3 host ) differs with the host species. Laboratory transmission studies of CCHF virus demonstrated that various native vertebrates become viremic, produce antibodies and are capable of horizontal transmission. Studies on human risk of infection undertaken in Yonofere, Senegal showed that 13% of people had been infected and prevalence increased with age: males and females were equally infected and risk in men was associated with bite by H. truncatum ticks and caring for sick animals. Two more strains of CCHF virus were isolated from pools of H. truncatum. (JS)