[Transstadial transmission of Francisella tularensis in the tick, Ixodes ricinus, infected during the larval stage].

Based on previous studies which proved the decisive importance of the degree of bacteraemia of experimentally infected white mice for the degree of infection of ticks Ixodes ricinus the authors confirmed the possibility of transstadial transmission of Francisella tularensis from larvae via nymphs to imagos by the detection of germs in the ticks and by experiments attempting their transmission to white mice. This applied to imagos even one year after the infection of larvae. Transmission was recorded even in imagos which did not transmit the infection in the nymphal stage. F. tularensis was repeatedly detected in the faeces of nymphs and imagos, which along with possible consumption of infected ticks by hosts, indicates further possibilities of transmission of the infection in nature. The results of quantitative examinations of the degree of infection of ticks enable us to conclude that the germs reproduce in the ticks after feeding on the host.