2024-04-26 09:12:05
How is Crimean-Congo hemorrhagic fever transmitted?
The Crimean-Congo hemorrhagic fever (CCHF) virus is mainly transmitted to animals or humans through bites of ticks of the genus Hyalomma. The species Hyalomma marginatum has been present for several decades in Corsica and since 2015 on the French Mediterranean coast. Climate change might contribute to expanding the range of these ticks.
Transmission by direct contact, mainly with blood and/or tissues and organs of infected animals or humans is also possible but more rare.
What are the symptoms ?
In humans, Crimean-Congo hemorrhagic fever generally manifests as a flu syndrome with digestive problems, which does not allow it to be distinguished from the classic symptoms of stomach flu. In certain cases, it can nevertheless worsen and result in a hemorrhagic syndrome, the fatality rate of which is 5 to 30% depending on the case.
What is the current situation and the risk of emergence in France?
At present, no cases of human contamination has not been recorded in France. On the other hand, the Crimean-Congo hemorrhagic fever virus was detected in October 2023 in ticks of the genus Hyalomma collected from cattle raised in the Pyrénées-Orientales. Around ten 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 to avoid contamination by the virus for the general population?
The main recommendations for prevention of Crimean-Congo hemorrhagic fever are the same as those usually recommended to avoid the transmission of pathogens by ticks, to know :
when walking in nature, wear closed shoes and light-colored covering clothing, in order to better spot ticks on the surface of the fabric, avoid walking among tall grass, bushes and low branches and favor paths marked, possibly use skin repellents with marketing authorization (AMM), respecting the recommendations for use, inspect yourself when returning from walks in the forest, in the maquis and scrubland or in the garden, particularly at the level of folds of the skin without forgetting the scalp, in the event of a bite, immediately detach the attached ticks using a tick remover, fine tweezers or failing that your nails and disinfect the wound, monitor the bite area for several days and consult your doctor in the event of symptoms (redness, fever, etc.).
Available data do not show transmission of the virus through the consumption of raw milk dairy products and meat from infected animals.
What are the recommendations for professionals and hunters?
In an expert report published in 2024, ANSES identified professions and activities involving a risk of being exposed to CCHF through contact with the blood and/or tissues and organs of an infected animal. Veterinarians, slaughterhouse operators, hunters and their companions are most at risk. Breeders and owners of ruminants and equines may also be exposed if they handle an animal that may bleed or when they manually remove ticks of the genus Hyalomma.
These people are advised to scrupulously respect hygiene measures and wear personal protective equipment suitable such as gloves, protective clothing, masks, goggles or visors, when handling a live animal that may cause bloodshed or when handling meat and offal from recently slaughtered or hunted.
What is ANSES’s role in the fight once morest Crimean-Congo hemorrhagic fever?
ANSES has carried out several assessments in order to to assess the risk of emergence of human cases in France and to recommend measures to monitor the evolution of the establishment of the virus and avoid contamination. Its laboratories also participate in projects and research on viruses and ticks. The Agency recommends intensifying information and awareness campaigns for professionals at risk of exposure and hunters.
To the extent that animals contaminated by the virus do not show symptoms, and the symptoms in humans are not specific, apart from serious cases, ANSES strongly recommended the establishment of national surveillance of ticks of the Hyalomma genus and the pathogens they carry, which is the only way to identify the possible progression of the virus’s implantation area.
Finally, it recommends conducting research to better understand the factors influencing the epidemiology and spatio-temporal dynamics of the CCHF virus and its tick vectors.
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