Role of ticks in the transmission of Crimean-Congo hemorrhagic fever virus

Abstract

Ticks were suspected of transmitting Crimean-Congo hemorrhagic fever (CCHF) virus (CCHFV) shortly after the disease was formally described in the mid-1940s [6], and inoculation of tick suspensions into human volunteers confirmed that ticks contained a filterable agent that caused CCHF [5, 6, 8,]. Initial epidemiological studies indicated that cases of this newly described disease occurred during the spring and summer; cases were often sporadic with no direct contact between patients; nearly all of the patients had a history of a recent tick bite; and there was little evidence of mosquito, sand fly, or other insect bites among these patients [6]. Studies conducted since then have consistently found a relationship between various tick species and the presence of CCHFV, and ticks are believed to be the principal means of viral transmission and persistence in nature [4, 8, 17, 43]. CCHFV has been detected in or isolated from>30 species of ticks (Table 12-1). In addition, CCHFV has been isolated from Culicoides species flies on at least two occasions [3, 25]. However, the mere isolation of a virus from an arthropod does not mean that the arthropod is involved in the natural transmission of that virus.