The natural infection of birds and ticks feeding on birds with Rickettsia spp. and Coxiella burnetii in Slovakia

Ixodid ticks (Acari: Ixodidae) are known as primary vectors of many pathogens causing diseases in humans and animals. Ixodes ricinus is a common ectoparasite in Europe and birds are often hosts of subadult stages of the tick. From 2012 to 2013, 347 birds belonging to 43 species were caught and examined for ticks in three sites of Slovakia. Ticks and blood samples from birds were analysed individually for the presence of Rickettsia spp. and Coxiella burnetii by PCR-based methods. Only I. ricinus was found to infest birds. In total 594 specimens of bird-attached ticks were collected (451 larvae, 142 nymphs, 1 female). Altogether 37.2 % (16/43) of bird species were infested by ticks and some birds carried more than one tick. The great tit, Parus major (83.8 %, 31/37) was the most infested species. In total, 6.6 and 2.7 % of bird-attached ticks were infected with Rickettsia spp. and C. burnetii, respectively. Rickettsia helvetica predominated (5.9 %), whereas R. monacensis (0.5 %) was only sporadically detected. Coxiella burnetii was detected in 0.9 %, Rickettsia spp. in 8.9 % and R. helvetica in 4.2 % of bird blood samples. The great tit was the bird species most infested with I. ricinus, carried R. helvetica and C. burnetti positive tick larvae and nymphs and was found to be rickettsaemic in its blood. Further studies are necessary to define the role of birds in the circulation of rickettsiae and C. burnetii in natural foci.