Giant Ticks in France Detected Carrying Crimean-Congo Hemorrhagic Fever Virus

The giant ticks Hyalomma marginatum, found along the French Mediterranean coast, have been identified as carriers of the Crimean-Congo hemorrhagic fever virus. This virus has been detected in several departments of the country.

These ticks, which can grow up to twice the size (8 mm) of a standard tick and are recognizable by their striped legs, have been colonizing the French Mediterranean coast. Unlike their cousin Ixodes ricinus, which transmits Lyme disease or tick-borne encephalitis, the giant tick also adapts better to temperature and humidity variations. Present in metropolitan France since 2015, it is capable of transmitting the Crimean-Congo hemorrhagic fever virus (CCHF). The virus was identified in ticks collected in Corsica and Pyrénées-Orientales in 2023.

Crimean-Congo hemorrhagic fever presents mainly with flu-like symptoms (fever, pain, digestive issues). In more severe cases, patients may experience bleeding and organ failure. While no human cases have been reported in France to date, caution is advised during outdoor activities in nature (scrubland, maquis, pastures, hiking trails, agricultural areas, etc.). People in contact with livestock or large wild animals are also urged to take precautions, as contact with fresh animal blood can transmit the virus.

Preventive measures against Hyalomma marginatum are similar to those for Ixodes ticks. It is recommended to wear covering and light-colored clothing during outdoor activities to better spot ticks. Closed-toe shoes are also recommended. However, mosquito repellents have limited effectiveness against these ticks, according to Santé publique France. After outdoor excursions, a visual inspection can help identify any ticks. Tick removal can be done using a tick remover or tweezers.

Hyalomma marginatum ticks have been reported in 11 French departments: Alpes-Maritimes, Ardèche, Aude, Bouches-du-Rhône, Corse-du-Sud, Drôme, Gard, Haute-Corse, Hérault, Pyrénées-Orientales, Var.

**Audrey Vaugrente**