"Giant tick" attacks: dynamics of Hyalomma lusitanicum and detection of Rickettsia sibirica mongolitimonae in southern France.

Since 2019, media reports have raised concerns about the emergence of "giant ticks" in Europe, particularly Hyalomma marginatum, due to its potential to transmit the Crimean-Congo haemorrhagic fever virus (CCHFV). In 2022, following several reports of unusually large ticks displaying aggressive behaviour toward humans in the Étang de Bolmon area (Bouches-du-Rhône, southern France), a popular area for walking and nature exploration, an investigation was conducted to characterise the local tick fauna, their seasonal activity, and associated microorganisms. Between 2022 and 2025, a total of 2,940 ticks were collected through environmental and host-based sampling, with 89% obtained from the ground and 11% from rabbits. Morphological, molecular, and MALDI-TOF mass spectrometry analyses were carried out and four species were identified: Hyalomma lusitanicum (78%), Rhipicephalus pusillus (22%), Haemaphysalis hispanica (<1%), and Ixodes ventalloi (<1%). The "giant ticks" were identified as H. lusitanicum, not H. marginatum. Molecular screening revealed Rickettsia sibirica mongolitimonae in H. lusitanicum, suggesting its role in the ecology of this emerging human pathogen, along with the endosymbiont Candidatus Midichloria mitochondrii. This work also confirmed the accuracy of MALDI-TOF MS as a reliable tool for rapid tick identification and highlights the re-emergence of H. lusitanicum in southern France, while indicating that the associated risk to human public health currently remains relatively limited.