[Effect of Borrelia--the causative agent of tick-borne relapsing fever--on the vector]

Direct or indirect evidence of pathogenic effect of Borrelia sogdiana, a tick-borne recurrent fever causative agent, on Ornithodoros papillipes is obtained, pointing to a parasitic character of their relations. Differences between infected and uninfected ticks are revealed both under normal life conditions (lower survival, more intensive process of moult), as well as under the effect of poison. Higher sensitivity of infected ticks to DDT was established experimentally; HCCH effect was determined indirectly by counting ticks after treatment. Authors suggest that the effect of causative agent on ticks' viability is more expressed under the conditions close to emergency.