Crimean-Congo Hemorrhagic Fever Virus: An Emerging Threat in Europe with a Focus on Epidemiology in Spain

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease transmitted by ticks of the genus Hyalomma and caused by a virus of the Nairoviridae family. In humans, the virus can generate different clinical presentations that can range from asymptomatic to mild illness or produce an hemorrhagic fever with a mortality rate of approximately 30%. The virus pathogenicity and the lack of effective treatment or vaccine for its prevention make it an agent of concern from a public health point of view. The main transmission route is tick bites, so people most exposed to this risk are more likely to become infected. Another risk group are veterinarians and livestock farmers who are in contact with the blood and other fluids of animals that are mostly asymptomatic. Finally, due to its first phase with a non-characteristic symptomatology, there exists a risk of nosocomial infection. It is endemic in Africa, the Balkans, the Middle East, and those Asian countries south of the 50th parallel north, the geographical limit of the main vector. Recently, autochthonous cases have been observed in areas of Europe where the virus was not previously present. Human cases have been detected in Greece, Bulgaria, and Spain. Spain is one of the most affected countries, with a total of 17 autochthonous cases detected since 2013. In other countries, such as France, the virus is present in ticks and animals but has not spread to humans. A high-quality epidemiological surveillance system in these countries is essential to avoid the expansion of this virus to new areas and to limit the impact of current cases.