Spatial and Phylodynamic Survey on Crimean-Congo Hemorrhagic Fever Virus Strains in Northeast of Iran

Crimean-Congo hemorrhagic fever (CCHF) is asymptomatic in infected animals, yet the virus poses a serious threat to humans causing a symptomatic, hemorrhagic disease with a high case-fatality rate. Numerous genera of ticks serve as both vectors and reservoirs of the Crimean-Congo hemorrhagic fever virus (CCHFV).
The aim of the present study is to determine the CCHFV prevalence in ticks from northeast Iran to establish a phylogenetic relationship of the tick-derived CCHFV strains circulating in Iran.
During April to June 2015, a total of 93 hard ticks were collected from different animals in the Damghan district. The S-segment of positive samples was fully sequenced using the Sanger technique. A total of 142 CCHFV sequences comprised full-length of CCHFV sequences obtained in this study were aligned using the MAFFT algorithm, then phylogenetic tree was constructed using Geneious v 7.1.8.
The identified tick species included Hyalomma marginatum (6.5%), Hy. dromedarii (21.5%), Hy. anatolicum (15.1%), Hy. asiaticum (3.2%) and Hy. schulzei (2.2%), as well as Rhipicephalus sanguineus (47.3%). The CCHFV RNA was detected in 4 samples of 93 tick samples (4.3%) by RT-PCR. A total of 4 CCHFV sequences were obtained in this study clustered within clade IV (Asia-1 and Asia-2).
We demonstrated that 4 species of hard ticks could be a vector for CCHFV in Iran. In addition, our findings indicate the circulation of CCHFV clade IV strain in the northeast of Iran and provide a solid base for more targeted surveillance and prevention programs in Iran.