Comparing tick-borne pathogen occurrence in different regions of Stornorrland

Sammanfattning

Ticks present in Sweden can transmit multiple vector-borne pathogens to both humans and animals, and as the habitat range of Ixodid species expands northward, there is a concern that the prevalence of these pathogens may increase in these regions. In total, 397 ticks, collected from northern Sweden and previously extracted for the screening of tick-borne encephalitis virus (TBEV), were used in this study to attempt to determine the occurrence of several bacterial and protozoal vector-borne pathogens in ticks from these regions. Borrelia spp, Babesia spp, Anaplasma phagocytophilum, and Francisella tularensis were chosen as the pathogens of interest. The extracted ticks were screened for these pathogens using individual qPCR assays, with certain assays being followed up with gel electrophoresis and sequencing to identify samples to species level. The results were split into two categories due to one large cluster of samples from the same date and location. Excluding this cluster, 20.3% of ticks tested positive for Borrelia spp, 0.7% tested positive for A. phagocytophilum, and none tested positive for either Babesia spp. or F. tularensis. The samples from the cluster only tested positive for Borrelia spp, but at a much higher prevalence of 71%. However, more diverse sampling would be needed from this region to determine if the prevalence of Borrelia spp. is truly higher than elsewhere. Excluding the cluster, the results indicate a similar prevalence of Borrelia spp. as is seen in southern Sweden, but a far lower prevalence of A. phagocytophilum; however larger sample sizes for future studies may give more accurate prevalence figures for all of the above pathogens.