Identification of tick-borne encephalitis virus in ticks collected in southeastern Hungary

Tick-borne encephalitis virus (TBEV) is an arthropod-borne viral pathogen causing infections in Europe and is responsible for most arbovirus central nervous system infections in Hungary. Assessing the TBEV prevalence in ticks through detection of genomic RNA is a broadly accepted approach to estimate the transmission risk from a tick bite. For this purpose, 2731 ticks were collected from the neighboring area of the town of Dévaványa, located in southeastern Hungary, which is considered a low-risk-transmission area for TBEV. Altogether, 2300 ticks were collected from the vegetation, while 431 were collected from rodents. Samples were pooled and then screened for TBEV with a newly designed semi-nested RT-PCR (RT-snPCR) targeting the NS1 genomic region. PCR results were confirmed by direct sequencing of the second round amplicons. Among the 3 different collected tick species (Ixodes ricinus, Haemaphysalis concinna, Dermacentor marginatus), I. ricinus was the only species that tested positive for TBEV. TBEV-positive ticks were collected from small mammals or from the vegetation. One nymphal pool and 4 larval pools tested positive for TBEV. The only positive nymphal pool was unfed and came from vegetation, while ticks of the 4 positive larval pools were collected from rodents. Minimal TBEV prevalence in ticks was 0.08% for unfed nymphs and 0.78% for feeding larvae. Our results indicate that further long-term investigations on the occurrence of TBEV are needed to better describe the geographic distribution and the prevalence of infected ticks in Hungary.