Survey of Crimean-Congo Hemorrhagic Fever Enzootic Focus, Spain, 2011-2015

Abstract

During 2011-2015, we conducted a Crimean-Congo hemorrhagic fever virus (CCHFV) survey in captured ticks that were feeding mainly on wild and domestic ungulates in Spain, where presence of this virus had been reported previously. We detected CCHFV RNA in Hyalomma lusitanicum and H. marginatum ticks for 3 of the 5 years. The rate of infected ticks was 2.78% (44/1,579), which was similar to those for other countries in Europe with endemic foci for CCHFV (Kosovo, Bulgaria, and Albania). These data confirm the established spread of CCHFV into western Europe. Phylogenetic study of the small RNA segment showed Africa-3 clade as the only genotype identified, although we observed cocirculation of genetic variants during 2011 and 2015. We could not rule out genetic reassortments because of lack of sequence data for the medium and large RNA segments of the virus genome.

Keywords: CCHFV; Crimean Congo hemorrhagic fever virus; Crimean-Congo hemorrhagic fever; Hyalomma spp. ticks; Spain; endemic circulation; enzootic focus; molecular epidemiology survey; phylogenetic analysis; reverse transcription PCR; tick-borne infections; vector-borne infections; viruses; zoonoses.

Figure 1

Study site locations in the Iberian Peninsula in which Crimean-Congo hemorrhagic fever virus was detected: Cáceres, Toledo, Segovia, and Huesca Provinces. Square shows presence of CCHFV in humans bitten by a tick, star shows presence of CCHFV in ticks with positive results by PCR, circle indicates region where serum samples positive for CCHFV were detected in Portugal, and white area shows regions in 4 localities (Cáceres, Ávila, and Toledo Provinces and Madrid) in Spain where CCHFV-positive ticks had been previously identified.

Figure 2

Maximum clade credibility genealogy based on partial (175-nt) sequences of the Crimean-Congo hemorrhagic fever virus small RNA segment of viruses from Spain and reference sequences. Numbers along branches indicate posterior probability values for the groups (values <0.70 are not shown). Triangles indicate newly sequenced strains from Spain reported in this study, which are identified by geographic origin, sampling site, and sampling year. Other sequences are indicated by GenBank accession number, strain, geographic origin, and sampling year. Sequences from this study indicated with an asterisk are included in European Molecular Biology Laboratory/GenBank databases. Genotypes are indicated in roman numerals and named according to Carroll et al. (30). Equivalent clade nomenclature is listed according to Chamberlain et al. (31) and indicated at right. Scale bar indicates nucleotide substitutions per site.