Crimean-Congo Hemorrhagic Fever Virus in Ticks, Southwestern Europe, 2010

To the Editor: Crimean-Congo hemorrhagic fever virus (CCHFV; family Bunyaviridae, genus Nairovirus) causes outbreaks of severe hemorrhagic fever in humans, with case-fatality rates <30% (1,2). The disease was initially recognized by Russian scientists in the 1940s (3), and the virus was fi rst isolated in the Democratic Republic of Congo some years later (4). CCHFV is reported throughout broad regions of Africa, Europe, the Middle East, and Asia. Reports linking transmission of the virus with an infected vector have involved ticks of the genus Hyalomma (5). It appears that maintenance of active foci of CCHFV in the fi eld is dependent on Hyalomma spp., even within periods of silent activity. Several vertebrates are involved in the natural transmission cycle (6). Transmission of CCHFV to humans occurs through tick bites, direct contact with blood or tissues of infected animals, person-to-person spread, or by nosocomial infection (1). In southeastern Europe, the Balkans are the known western limit for CCHFV (7). This fi nding is of special interest because Hyalomma marginatum, the main tick vector in the western Paleartic (an ecozone that includes temperate and cold areas of Eurasia and North Africa and several archipelagos and islands in the Atlantic and Pacifi c Oceans), is common throughout the Mediterranean Basin (7), where clinical cases of the disease or the virus have not been reported. Unsupported claims of the effects of climate on virus distribution have been reported but never empirically demonstrated (8). We report the detection of CCHFV in ticks collected in southwestern Europe. A total of 117 semi-engorged adult H. lusitanicum ticks were collected from 28 adult red deer (Cervus elaphus) in November 2010, at a site (39.63°N, 7.33°W) in Cáceres, Spain. Live ticks were transported to the special pathogens laboratory at Hospital San Pedro–CIBIR in Logroño (northern Spain), classifi ed, and frozen at −80°C. For RNA extraction, specimens were washed in 70% ethanol and then in Milli-Q water (Milli-Q Advantage water system; Spain) that had been autoclaved. Each tick was cut lengthwise; half was used for additional processing and the remainder was stored. Before use, each half was crushed in sterile conditions. RNA was individually extracted by using the RNeasy Mini Kit (QIAGEN, Hilden, Germany) according to the manufacturer's instructions and frozen at −80°C. The RNA was distributed in 12 pools and retrotranscribed by using the Omniscript RT kit (QIAGEN) according to the manufacturer's instructions and then frozen at −20°C. Nested …