Trypanosoma vespertilionis detected but not Spiroplasma ixodetis in Carios vespertilionis (short-legged bat ticks) collected in Sweden

From a One Health perspective, ticks play a key role as vectors of infectious agents, whereas bats can act both as hosts for ticks and as reservoirs of the agents, thereby contributing to transmission of infection. In Sweden, the argasid (soft) tick Carios vespertilionis , which is associated with the soprano pipistrelle ( Pipistrellus pygmaeus ), is the only known bat-associated tick species. Our study investigated Trypanosoma species and Spiroplasma ixodetis in C. vespertilionis , assessing the potential role of this tick species as a vector. A total of 78 ticks, collected in 2015 and 2018, representing all active developmental stages, were analysed using real-time PCR, and positive samples were subsequently subjected to further molecular examination. Trypanosoma DNA was detected in 22 ticks, with sequence analyses confirming the species as Trypanosoma vespertilionis . No samples tested positive for S. ixodetis . These findings provide molecular evidence of T. vespertilionis in C. vespertilionis in Sweden, showing that soft ticks can naturally harbour Trypanosoma species. The observed increase in prevalence across tick developmental stages suggests an accumulative effect of repeated blood-feeding, which could indicate some level of parasite persistence. Nevertheless, Trypanosoma DNA may originate from ingested host blood rather than established infection, and any potential vector role of this tick species should therefore be interpreted with caution.