Crimean-Congo hemorrhagic fever virus: genetic analysis and tick survey in Turkey

Abstract

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus in the family Bunyaviridae, genus Nairovirus. The virus is transmitted to humans through infected tick bites or from direct contact with viremic animals or humans. In the present study, a total of 1,015 adult ticks were collected from cattle (603 specimens), sheep (17 specimens), and goats (395 specimens) in the Kelkit Valley in Turkey. Four tick species were recognized on the animals in the surveyed region. The most abundant species were Rhipicephalus bursa and Hyalomma marginatum marginatum, at 47.68% (484/1,015) and 46.40% (471/1,015), respectively. Reverse transcriptase PCR was used to recover partial sequences of the CCHFV small (S) genome segment. The presence of CCHFV was determined in 3 of 33 (9.09%) R. bursa pools and in 1 of 31 (3.22%) H. m. marginatum pools. Virus sequences from R. bursa were extremely different from those of the Greek CCHFV strain (U04958) isolated from an R. bursa tick. Phylogenetic analysis indicated that the CCHFV isolates obtained in this study clustered in group 5, whose range encompasses southwestern Russian and Kosovo. This is the first evidence of CCHFV in ticks from Turkey. Even though Hyalomma is the main vector for CCHFV, R. bursa may play a role in CCHFV transmission.

FIG. 1.

Map of Turkey and of the Kelkit Valley showing the locations of the study sites. (Copyright Selcuk Hayli; reproduced with permission.)

FIG. 2.

Phylogenetic tree based on 216 nt of the small (S) segment of CCHFV. The tree was generated by the neighbor-joining method with Kimura two-parameter distances using MEGA software (version 3.1). Bootstrap confidence limits were based on 500 replicates. The numerical values in the tree represent bootstrap results. The GenBank accession number and the geographic origin are given for each isolate. Newly sequenced strains from Turkey described in this paper are shown in boldface. Dugbe and Hazara viruses were used as the outgroups. The genetic lineages of CCHFV are numbered 1 to 7. UAE, United Arab Emirates; CAR, Central African Republic.