Diversity of tick species and associated pathogens on peri-urban wild boars - First report of the zoonotic Babesia cf. crassa from Hungary

Wild boars show increasing numbers and population densities throughout Europe, including Hungary. While their presence is appreciated as game animals, they are also responsible for significant agricultural damage, habitat degradation and water quality issues. In addition, wild boars may harbor ticks and can act as reservoirs of tick-borne pathogens, thus posing a risk of transmission towards humans and domestic animals. This latter aspect of their veterinary-medical and epidemiological significance has become especially important in recent years, because increasing numbers of wild boars are reported to enter urban areas. Despite of this, reports on tick infestations of wild boars are scarce in Europe. For this study, 333 ixodid ticks were collected from 51 wild boars at 32 peri-urban locations in 14 counties of Hungary, during 2005-2008 (older samples) and 2019-2020 (new samples). Five species of ticks were identified: Dermacentor reticulatus (n = 165), Ixodes ricinus (n = 90) and Haemaphysalis concinna (n = 29) in both sample groups, while H. inermis (n = 29) and D. marginatus (n = 20) were only found among the old samples. The seasonality of collected ticks corresponded to their known activities. After DNA extraction, ticks were screened for three groups of tick-borne pathogens. All samples were negative for brucellae, recently reported to be carried and transmitted transovarially by D. marginatus. Four D. reticulatus contained Babesia canis DNA, while in one H. concinna nymph the recently discovered zoonotic B. cf. crassa (reported in Slovenia within 80 km of our sampling site) was detected. In addition, Anaplasma phagocytophilum was identified in D. reticulatus (n = 1), H. concinna (n = 3) and in its known vector, I. ricinus (n = 15). Phylogenetically, three out of four A. phagocytophilum genotypes clustered with zoonotic ones. In conclusion, despite of the high prevalence of Brucella suis in wild boars in Hungary, no evidence was found in support of the epidemiological role of ticks in transmitting brucellae. On the other hand, wild boars might introduce B. canis-carrier D. reticulatus into urban areas, unlike birds (which are not known to carry this tick species in the country). Most importantly, tick-infested wild boars can contribute to the spread of a novel zoonotic Babesia sp. and of the zoonotic variants of A. phagocytophilum.

Automated summary

This study found that various ticks carrying tick-borne pathogens were found on wild boars in peri-urban areas of Hungary, suggesting that wild boars may play a significant role in the transmission of tick-borne diseases.