Risk of emergence of Crimean-Congo haemorrhagic fever in France
Crimean-Congo haemorrhagic fever is a potentially fatal disease in humans, transmitted by certain ticks. Although no indigenous human cases have yet been reported in France, there is a real risk of this disease emerging in the country.
How is Crimean-Congo haemorrhagic fever transmitted?
The Crimean-Congo haemorrhagic fever (CCHF) virus is mainly transmitted to animals or humans through bites from ticks of the genus Hyalomma. The Hyalomma marginatum species has been present in Corsica for several decades and on the French Mediterranean coast since 2015. Climate change may play a part in expanding the range of these ticks.
Transmission by direct contact, mainly with the blood and/or tissues and organs of infected animals or humans, is also possible but remains rare.
What are the symptoms?
In humans, Crimean-Congo haemorrhagic fever generally causes an influenza-like illness with digestive disorders, making it indistinguishable from the classic symptoms of stomach flu. In some cases, however, it can worsen and lead to a haemorrhagic syndrome, which has a mortality rate of between 5% and 30% depending on the case.
What is the current situation and risk of emergence in France?
To date, no cases of human contamination have been identified in France. However, in October 2023, the Crimean-Congo haemorrhagic fever virus was detected in ticks of the genus Hyalomma collected from cattle reared in the Pyrénées-Orientales département. Around 10 indigenous human cases of CCHF have been reported in Spain since 2013, some of which resulted in the death of the patient. Transmission of the virus to humans in France is therefore possible.
How can the general population avoid infection by the virus?
The main recommendations for preventing Crimean-Congo haemorrhagic fever are the same as those usually given for avoiding pathogen transmission by ticks, namely:
- when walking in the countryside, wear closed shoes, avoid exposed skin and wear light-coloured clothing (to more easily spot ticks on the surface of the fabric),
- avoid walking through long grass, bushes and low branches and keep to signposted paths,
- if necessary, use skin repellents with marketing authorisation (MA), but be sure to follow the recommendations for use,
- when returning from a walk in woodlands, maquis or garrigue scrubland, or even from the garden, check your skin – especially the folds – and your scalp for ticks,
- if you are bitten, remove the attached ticks immediately using a tick remover, fine tweezers or, failing that, your nails, and then disinfect the wound,
- monitor the bite area for several days and see your doctor if symptoms (redness, fever, etc.) develop.
The available data do not show any virus transmission through the consumption of raw-milk dairy products or meat from infected animals.
What are the recommendations for professionals and hunters?
In an expert appraisal published in 2024 (PDF in French), ANSES identified certain professions and activities at risk of exposure to CCHF through contact with the blood and/or tissues and organs of infected animals. Veterinarians, slaughterhouse operators, hunters and their companions were found to be most at risk. Breeders and owners of ruminants and equines may also be exposed if they handle an animal that may be bleeding or if they manually remove ticks of the genus Hyalomma.
These people are advised to strictly comply with hygiene measures and wear suitable personal protective equipment, such as gloves, protective clothing, masks, goggles or visors, when handling live animals that may be spurting blood, or meat and offal from recently slaughtered or hunted animals.
What is ANSES's role in combating Crimean-Congo haemorrhagic fever?
ANSES has conducted several expert appraisals to assess the risk of human cases emerging in France and recommend measures for monitoring changes in where the virus is established and preventing contamination. Its laboratories are also participating in projects and research into the virus and ticks. The Agency recommends stepping up campaigns to inform and raise awareness among at-risk professionals and hunters.
Because animals contaminated by the virus do not show any symptoms, and symptoms in humans are not specific, apart from serious cases, ANSES strongly recommends the introduction of national surveillance for ticks of the genus Hyalomma and the pathogens they carry, which is the only way of identifying any spread in the area where the virus is established.
Lastly, it recommends research to better understand the factors influencing the epidemiology and spatio-temporal dynamics of the CCHF virus and its tick vectors.