[Anti-pertussis immunity in children in the cities of Northwestern Federal District with various population].

AIM: Evaluate the state of immunity against pertussis in children living in St. Petersburg and regional centers of Northwestern Federal District (NFD). MATERIALS AND METHODS: The level of anti-pertussis antibodies by EIA and agglutinin reaction (AR) was studied in 419 children living in St. Petersburg and by AR in 239 children living in regional centers of NFD. Blood sera in AR were studied by using liquid pertussis diagnosticum (Biomed, Russia). RESULTS: In St. Petersburg the frequency of detection of high level of antibodies was the highest in the 15 - 17 age group that indicates a high level of latent morbidity in grownups. The frequency of detection of high level of antibodies in the 3 - 4 and 9 - 10 age groups in regional centers was significantly lower, and the fraction of sera with undetected level of antibodies--significantly higher compared with St. Petersburg, that gives evidence on low circulation of causative agent, lack of "epidemizing" of children in small cities. CONCLUSION: The question of introduction of second revaccination against pertussis in children at the age of 6 is actual, because one vaccination is not enough for prolonged sustaining of population immunity intensity.

[Molecular typing of the strains of Bordetella pertussis circulating in St. Petersburg during an outbreak of the disease].

Growth of the whooping-cough morbidity during the last years in Russia and other countries with 40-year-long history of immunization gave rise to significant interest of researchers to variability of the Bordetella pertussis population. Comparative assay of the genomes of the B. pertussis strains circulating in St. Petersburg in 1998-2000 and strains used to produce domestic vaccines AKDS was performed using the pulse-field electrophoresis and sequencing. It was found that most strains of B. pertussis circulating during this period were distinguished from the vaccine strains by the DNA-profile and structure of genes involved in encoding of biosynthesis of the S1 subunit of the whooping-cough toxin (ptxS1) and pertactin (prn). It was shown that 62% of wild-type strains had electrophoretic profiles IV alpha and IV beta, whereas vaccine strains had electrophoretic profiles II and III. Circulation of strains with profiles IV alpha and IV beta was found to correlate with the whooping-cough morbidity rate in vaccinated children. Our results and data of other researchers were compared and analyzed.