Human babesiosis and tick-borne encephalitis

Ixodes species ticks are abundant this spring and summer with temperatures and humidity ideally placed for tick activity. Lyme disease remains the most common Ixodes-transmitted pathogen of veterinary significance, affecting dogs, cats and people. However, in the past month attention has been drawn to two other Ixodes-associated pathogens causing cases of human disease. A human case of babesiosis caused by Babesia venatorum has been recorded in the UK for the first time, alongside only the second UK case of tick-borne encephalitis.

There are several Babesia spp. present in the UK, with Babesia canis transmitted by Dermacentor reticulatus the most pathogenic in dogs. Other Babesia spp. transmitted by Ixodes spp. ticks, while less pathogenic in pets, are zoonotic. B. venatorum is notable in that it appears able to infect humans without immune suppression or splenectomy, and resultant disease can be more severe than in other zoonotic Babesia spp. (Herwaldt et al, 2003).