Structure of Population of Strains of the Bordetella pertussis in the Russia

Abstract

Relevance. Despite more than 50 years of successful experience with pertussis immunization, pertussis remains an important public health problem. WHO estimated 16 million people worldwide are infected per year, a significant number of whom are children under 1 year of age. In the last 10 years a significant increase in the incidence of whooping cough has been observed in many countries with a high immunization coverage level. In Russia, specific prevention of whooping cough, is held since 1959. Specific prevention of whooping cough has led to considerable improvement of an epidemiological situation and has shown its social and economic importance for maintenance of sanitary and epidemiologic wellbeing on this infection in Russia. Goal. Study the structure of population B. pertussis circulating in Russia in dynamics of whooping cough epidemic process. Materials and methods Studied 573 B. pertussis strains allocated from patients with whooping cough in 1948 - 2015 used multilocus sequence typing (MAST). Isolates divided in five groups: 1948 - 1969 - 37 strains, isolated in the vaccination period and the first ten years of mass childhood immunization; 1970 - 1989 - 63 strains; 1990 - 2005 - 203 strains (from G.N. Gabrichevsky Institute of Epidemiology and Microbiology collection); 2006 - 2012 - 185 strains; 2013 - 2015 - 85 strains. Genotyping of strains was carried out according to the scheme MAST2 on the basis of a sequence of fragments of genes of ptxP-fim3-prn. Results of sequencing-typing were computed in the CromasLite program, identification of alleles and sequencing types carried out on EMBL/GenBank. Results. Formation of population of B.pertussis strains during more than 50 years went on the way of consecutive change of vaccinal genotype strains with strains of new nonvaccinal genotypes. Conclusions. Modern population of the causative agent of whooping cough is presented by the strains of genotype 322 and 329 possessing high virulence and causing heavier clinical course of disease.