[The results of a 15-year study of the persistence of Yersinia pestis L-forms].

New diagnostic preparations for the detection of L-forms, immunoglobulin erythrocyte diagnosticum and luminescent antimembrane immunoglobulins, are described. Proofs indicating that Y.pestis L-forms are constantly isolated from wild rodents and their ectoparasites in the natural foci of plague are given. To control the effectiveness of the sanitation of such natural foci, the use of the radioimmunoassay and the enzyme immunoassay, known to be the most sensitive techniques, are recommended. The facts indicating that Y.pestis contaminating ticks and fleas are converted into L-forms, capable of persisting for several years, are presented. After their reversion to back the initial rod-shaped form the transmission of infection is possible. A suggestion is put forward that the persisting forms of Y.pestis play an important role in the preservation of this infective agent in the natural focus of infection.