An Overview: Far Eastern Scarlet-Like Fever is a Special Clinical and Epidemic Manifestation of Yersinia pseudotuberculosis Infection in Russia

Pseudotuberculosis in humans until the 1950s was found in different countries of the world as a rare
sporadic disease that occurred in the form of acute appendicitis and mesenteric lymphadenitis. In
Russia and Japan, the Yersinia pseudotuberculosis (Y. pseudotuberculosis) infection often causes
outbreaks of the disease with serious systemic inflammatory symptoms, and this variant of the
disease has been known since 1959 as Far Eastern Scarlet-like Fever (FESLF). Russian researchers
have proven that the FESLF pathogen is associated with a concrete clonal line of Y.
pseudotuberculosis, characterized by a specific plasmid profile (pVM82, pYV 48 MDa), sequence
(2ST) and yadA gene allele (1st allele). The detection of the first cases of pseudotuberculosis in
people abroad was the result of random findings in lethal septic diseases diagnosed on the basis of a
bacteriological study of sectional material. This review summarized the most important achievements
in the study of FESLF since its discovery in the Far East. It has been established that the FESLF
causative agent is characterized by a unique phenomenon of psychrophilicity, which consists of its
ability to reproduce in the environment with its biologically low and variable temperature (4–12°C), at
which the pathogen multiplies and accumulates while maintaining or increasing its virulence, which
ensures the emergence and development of the epidemic process. The key genetic and biochemical
mechanisms of Y. pseudotuberculosis adaptation to changing environmental conditions were
characterized, and the morphological manifestations of the adaptive variability of these bacteria in
different conditions of their habitat were revealed. The main features of the pathogenesis and
morphogenesis of FESLF, including those associated with the Y. pseudotuberculosis toxigenicity,
were presented. The pathogenetic value of the plasmid PVM82, found only in the FESLF pathogen,
was shown. Recently, the relevance of further research on the problem of FESLF has been
associated with the study of dormant forms of Y. pseudotuberculosis and the idea of
pseudotuberculosis as a persistent infection.