Chitimia-Dobler et al.
Repeated isolation of tick-borne encephalitis virus from adult Dermacentor reticulatus ticks in an endemic area in Germany
Parasit. Vectors. 2019;12:90, doi.org/10.1186/s13071-019-3346-6
The tick Dermacentor reticulatus, the ornate dog tick, belongs to the tick species, which has been described as vector for TBE virus. In some regions of Poland, the prevalence of TBE virus found in D. reticulatus reached up to 10%. In a northern district of the Federal State of Saxony (Germany), neighboring to Poland, and so far classified as a TBE non-endemic region, a case of human TBE was reported in 2016. In this area, more than 2000 ticks were collected during various seasons from 2016 to 2018. Most of the ticks were identified as Ixodes ricinus and D. reticulatus (sympatric occurence). TBE virus specific RNA could be found in both species. The minimum infection rate was similar for adult I. ricinus ticks and nymphs and also for D. reticulatus (0.42%-0.59%), and D. reticulatus may play a major part in the conservation of this natural TBE focus. The sequence of glycoprotein E was established from 11 positive pools and the analyses show that all virus strains belonged to one genetic cluster of TBE virus. Phylogenetic analysis of the sequences showed a close relationship to strains from Poland, southern Germany and Switzerland, and the isolates from D. reticulatus showed no differences to those from I. ricinus. The authors discuss the findings, stating that there was no genetic adaption when the virus changed from the vector I. ricinus to D. reticulatus.