[An experimental study of the possibility for the preservation of the causative agent of plague in the nest substrate of the long-tailed suslik].

How long Yersinia pestis can preserve in the nest substrate of Spermophililus undulatus and whether it can infect the animals contacting with the substrate infected with flea feces and carcasses were studied in a Tuva natural focus. The infected material was kept in special niches of a bunkering laboratory, which imitated a souslik nest. Biological, serological, and bacteriological studies were conducted after different storage periods. The experiment used 25 sousliks, 56 albino mice, and 3256 fleas. Two hundred and ninety flea carcasses were individually explored. Y.pestis was ascertained to survive in the nest substrate infected with flea feces and carcasses. The pathogen may be preserved as a mutant in the flea carcasses, as evidenced by the isolation of 6 Y. pestis cultures from flea carcasses as a L-form. There is evidence for the fact that healthy animals may be infected on their contact with the contaminated substrate.