[Virulent properties of Leishmania tropica major strains isolated from sandflies in the subzone of the northern deserts].

On the territory of the Karakalpak ASSR the infection of sand flies Ph. papatasi, Ph. caucasicus, Ph. andrejevi and Ph. monogolensis with the agent L. tropica major ammounts, on the average, to 39.3%. The virulence of 88 investigated strains of Leishmania for white mice estimated by their infection and the duration of incubation was found to be different; one half of the strains had high, one third--average, and the other strains--low virulence.