An emergence of Crimean-Congo hemorrhagic fever is possible in France, if a tick, carrying the virus and present on part of France, spreads more with climate change, warned Thursday the National Agency for Food, Environmental and Occupational Health and Safety (ANSES), calling for surveillance of these animals.
A vector of many pathogens, including the Crimean-Congo fever virus (CCHF), the Hyalomma tick is native to Africa and Asia. Introduced mainly by migratory birds from Africa, this tick has been present in Corsica for several decades and on the Mediterranean coast since 2015.
While "no human case of contamination by the Crimean-Congo fever virus has yet been observed", ANSES considers that "an emergence in France is possible", in an opinion and a report on the risks to human and animal health of Hyalomma ticks. A dozen indigenous human cases of this fever have been reported in Spain since 2013, some of which have led to the death of the patient, observes the agency.
30% case fatality
While this fever is usually limited to influenza-like illness with digestive disorders, "in some cases, it can worsen and result in a haemorrhagic syndrome, with a case fatality rate as high as 30% in some countries". In France, antibodies specific to the virus have been found in domestic and wild animals, also notes the health agency.
The risk of the appearance of Crimean-Congo fever in France is "all the more likely as the geographical extension of the area where ticks are established should be favoured by climate change", according to Elsa Quillery, coordinator of the scientific expertise cited by ANSES.
Dry climates and warm periods are prized by Hyalomma ticks, found until now in France especially in the scrubland or the Mediterranean scrub, unlike other ticks, rather forested. ANSES therefore calls for national surveillance of these ticks, targeting the most at-risk areas and developing tools to detect transmitted pathogens at an early stage.
Serious diseases spread by ticks
"Unlike mosquitoes, there is no national surveillance system for ticks, even though they transmit serious diseases such as CHF Canada but also Lyme disease or tick-borne encephalitis," Quillery said. Zoonoses, diseases transmitted to humans by animals, have multiplied in recent years, raising fears of new pandemics.
