Clinical-epidemiological aspects of whooping cough in children in conditions of mass vaccinoprophylactics

Abstract

The aim of the study was to present clinical, epidemiological and laboratory characteristics of modern pertussis in hospitalized children, as well as to assess the frequency of pertussis infection as an etiological factor of long – term cough in children and adolescents.Materials and methods: medical records of 545 patients hospitalized in Children’s city clinical hospital №5 named after N.F. Filatov (Saint-Petersburg) in the period 2015–2017 were analyzed. Detailed clinical and laboratory analysis with subsequent follow-up of patients was carried out in 80 patients with pertussis aged 1 month to 18 years. The DNA of the causative agents of pertussis infection was identified by PCR using a commercial kit “AmpliSens Bordetella multi-FL” (Moscow); parallel was determined the bacterial load by quantitative PCRRT (real time) using test systems production, Gamaleya Research Institute of Epidemiology and Microbiology (Moscow), allowing to detect a single genome-equivalents (GE) of B. pertussis in smears from the nasopharynx. Pertussis convalescents were examined 1, 3 and 6 months after discharge.Results. Among hospitalized children dominated the first 2 years of life (70.8%), 78% were unvaccinated children. The sources of infection for children of the first two years of life were family members in 77% of cases, for preschoolers-in 67%, for schoolchildren-in 14%. Patients of moderate severity were 81.1%, severe – 10.3%; mild – 7%. Of the specific complications, respiratory rhythm disturbances were notedin 11.6%, including respiratory arrest-in 2.8%; pneumonia of mixed etiology was recorded in 6.2% of cases. Introduction of PCR method allows to increase laboratory confirmation up to 87.2%. In 63.6% of cases pertussis of pertussis were detected by PCR genome-equivalents of DNA in 6 months from hospital discharge. In patients with long – term cough, pertussis wand DNA was detected in preschool children in 11.14% of cases, in patients 7–12 years – in 25.93%, in adolescents-in 20% of cases.Conclusion. Whooping cough is a common infection among schoolchildren and adolescents, despite the high coverage of young children with preventive vaccinations. Pertussis convalescents can release the DNA of the pathogen for a long time, which may have epidemiological significance for unvaccinated and those children and adults, who have lost postvaccinal immunity, in the foci of infection.