Veterinary session

Hard ticks (Acari: Ixodidae) are regarded as the most important arthropods that are able to transmit pathogens to humans and domestic animals in the temperate zone. Previously, in the capital city of Hungary various habitats were surveyed for the presence of ticks and tick-borne pathogens, and neglected parts of cemeteries were found to be especially suitable to maintain large tick populations, most likely because of the high density of birds and small mammals (i.e., due to the restricted entry or near absence of medium sized carnivores).

In a cemetery, we collected ticks with the dragging-flagging method from the vegetation during a 28-month period (February 2019 to May 2021), encompassing three spring and two autumn tick seasons. For comparison, ticks were also collected in an urban forest for 24 months (February 2019 to January 2021). The ticks were stored in ethanol until identification of their species based on standard morphologic keys. DNA was extracted from selected specimens for either molecular taxonomic analyses (complementing morphologic data) or for screening piroplasms. The former were based on conventional PCRs amplifying the cytochrome c oxidase subunit 1 (cox1) gene and the 16S rRNA gene of the ticks, whereas the latter targeted the 18S rRNA gene of piroplasms. The PCR products were sequenced and then compared to GenBank data with the BLASTn program.

In the cemetery, 3818 ticks were collected, including Ixodes ricinus (n=2772), Ixodes frontalis (n=350) and Haemaphysalis concinna (n=696). Ixodes ricinus showed activity throughout the year, peaking in March-May and September, while H. concinna was not active during winter months and early spring, with activity peak in May-June. Most I. frontalis nymphs were collected late winter and early spring (February-April), whereas the peak activity of larvae was during late autumn (October-November). This is the first seasonality assessment of I. frontalis in Central Europe. In the forested habitat only I. ricinus was found (n=292).

Results of the morphologic and molecular analyses were as follows. Three morphotypes and four malformed specimens of I. ricinus were not significantly different in their 16S rRNA haplotypes and phylogenetic clustering from the typical representatives of this species. Considering the haplotypes of 25 I. frontalis, the majority (n=19) belonged to haplotype-A, and in the nymph stage there were no evident morphologic differences between haplotypes-A and -B, confirming the status of these as cryptic species.

Among the 161 molecularly analyzed H. concinna specimens (collected in 2019) 31 were PCR positive for piroplasms. In these ticks Theileria capreoli (n=6, in nymphs and a female) and six Far-Eastern Babesia genotypes were identified (n=25, in larvae, nymphs and a male), including a zoonotic one. None of these appeared to show a consistent seasonality in their vector ticks.