Venereal and cannibalistic ways of Borrelia burgdorferi sensu lato exchange between males and females of Ixodes persulcatus (Ixodidae, Acarina).

Borrelia burgdorferi sensu lato (s. l.) infection rate in Ixodes persulcatus Shulze maintained in different relative humidity gradient in male and female pairs and separately by sex were compared. Ticks collected in the St. Petersburg Region of Russia during 1992-1994 temperate and 1995 hot seasons. We observed that the infection rate among specimens maintained as sexual pairs were 1.2-2.5 times higher than among ticks maintained separately. Rate of borrelia infection in tick couples was a bit higher among specimens collected within a hot spring-summer period than among ticks collected during the seasons with temperate temperatures. This pathogen interchange was thought to result from a venereal or cannibalistic (omovampiric) mode of borreliae transmission. Traces of male bites (scars) on the female bodies were checked more often during a hotter seasons. borrelia burgdorferi s.l. was determined to be present in 22.9-29.3% whereas infection occurred in 12-20% of single specimens. Our data indicate the importance of isolating ticks sexually during disease investigations with borreliae as well as tick-borne encephalitis and probably other tick-borne pathogens.