Identification of Hyalomma Ticks on Migratory Birds in Poland During the 2023 and 2024 Spring Seasons

Ticks from the Hyalomma genus have recently garnered public attention in countries in Northern and Central Europe, as they are transported by migratory birds and might have established stable populations due to climate warming. The main threat associated with Hyalomma ticks is their ability to transmit Crimean-Congo hemorrhagic fever virus (CCHFV), which can be fatal in up to 40% of cases. Here, we collected Hyalomma ticks from migratory birds during annual ringing actions in the spring seasons of 2023 and 2024. Four ticks were found on birds from the Acrocephalus genus and two on Hippolais icterina. The ticks were examined for the presence of Rickettsia spp., Babesia microti, Babesia divergens, Coxiella burnetii, Borreliella burgdorferi (s. l.), Anaplasma phagocytophilum, West Nile virus, and CCHF virus (CCHFV). The collected H. rufipes specimens were negative for tested pathogens, except for two ticks collected in 2024, which were positive for Rickettsia aeschlimannii. The data show that Hyalomma ticks are efficiently transported on birds preferring reedbeds or deciduous trees. The possibility of the occurrence of CCHF or rickettsiosis (induced by R. aeschlimannii) is currently assessed as low. Nevertheless, we have shown the transfer of Hyalomma ticks to Poland and indicated the need for careful future epidemiological monitoring of the presence of Hyalomma ticks.