BORRELIA-BURGDORFERI SENSU-LATO IN RUSSIA AND NEIGHBORING COUNTRIES -HIGH-INCIDENCE OF MIXED ISOLATES

A total of 365 isolates of Borrelia burgdorferi sensu late from 12 maj or administrative territories of Russia (from St. Petersburg in the we st to South Sakhalin in the east) and from the Czech Republic, Estonia , Lithuania, Byelorussia, Moldavia, Ukraine and Kirghizia were identif ied by analysis of restriction polymorphism of ribosomal rrf-rrl space r amplicons. The isolates were obtained mainly from Ixodes persulcatus and I. ricinus ticks. Other sources included small mammals, human pat ients and I. trianguliceps ticks. The results showed that B. garinii ( two variants) together with B. afzelii circulated throughout the terri tories studied. The distribution of the variant NT29 of the species B. garinii, the most frequently isolated, was associated with that of I. persulcatus ticks. B. burgdorferi sensu stricto, and the species B. v alaisiana and B. lusitaniae (formerly the genomospecies VS116 and Poti B2, respectively) were isolated only from I. ricinus ticks in the west ern part of the studied territories. None of these three species were found in 327 isolates from Russia where I. persulcatus is the most fre quently distributed vector. This work also provides evidence for a hig h incidence of mixed Borrelia infections within vectors and hosts (9.3 % of isolates were mixtures of Borrelia species). A detailed analysis of Borrelia species distribution over the territories studied is prese nted.