Replication of Crimean-Congo Hemorrhagic Fever Virus in Four Species of Ixodid Ticks (Acari) Infected Experimentally

The vector potentials of Hyalomma dromedarii Koch, H. impeltatum SchulzeSchlottke, H. truncatum Koch, and Rhipicephalus appendiculatus Neumann for Crimean-Congo hemorrhagic fever (CCHF) virus (IbAr 10200) were evaluated by intracoelomic inoculation. All three Hyalomma species became infected; infection rates ranged between 80 and 100% at 7-14 d after inoculation, and viral titers increased in unfed specimens almost 100 times above inoculation levels within the first week following infection. Only 40% of the R. appendiculatus became infected, and viral titers of unfed specimens increased less than 10 times above inoculation levels. The virus persisted to 153 d in unfed H. impeltatum. Viral titers were significantly higher in female than in male H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus after blood feeding. Blood feeding had little effect on the viral titers of male Hyalomma species. However, the percentage of female and male ticks from which virus was recovered was significantly higher from fed ticks compared with unfed ticks. No virological evidence of transovarial transmission was found in greater than 78,000 first-generation progeny (larvae, nymphs, and adults) of inoculated female H. dromedarii, H. impeltatum, H. truncatum, and R. appendiculatus. All species transmitted CCHF virus to guinea pigs when allowed to feed at both 6 and 21 d after inoculation.