BACKGROUND: We estimated what risk factors affect hospitalisation for confirmed pertussis cases among infants (child up to 1 year) in the Czech Republic based on data from the questionnaire-based enhanced surveillance system (ESS) in years 2015, 2017 and 2019. METHODS: Retrospective cohort study was conducted in which we assessed demographic, clinical data, vaccination status and risk/protective factors. Vaccination status was extracted from the electronic nationwide notification system (NNS). We performed descriptive, univariable and multivariable analysis using risk ratio (RR) and logistic regression with odds ratio (OR). RESULTS: A total of 104 confirmed cases (27, 13, 64) were reported in the ESS during 2015, 2017 and 2019. Most cases were in age group 1 month (24), more males (57). Fifteen cases were vaccinated and 89 unvaccinated. Of 88 hospitalised cases, 31 cases reported stay in Intensive Care Unit (ICU). The median length of hospitalisation was 8 days. Although the variable vaccinated in infants was statistically significant in a univariable analysis for outcome hospitalisation, RR 0.76 (95% CI 0.53-1.10), it was not in multivariable. Hospitalisation was strongly associated with the younger age group of 0-3 months adjusted by a smoking family member in a household (OR = 9.72; 95% CI: 2.97-31.81). Stay in ICU was strongly correlated with the younger age group of 0-3 months (OR = 5.07; 95% CI: 1.44-17.87) and with a contact with confirmed or probable pertussis (OR = 7.05; 95% CI: 1.36-36.52). CONCLUSIONS: Our study demonstrated younger age and contact with other pertussis case as risk factors for hospitalisation of infants with pertussis. It is necessary to consider adolescent and adult boosters, including vaccination during pregnancy. We suggest integrating the variables from the enhanced surveillance system into the nationwide notification system, in order to simplify the data reporting and evaluation. Further studies are needed to evaluate the ESS and to monitor the vaccination of pregnant women against pertussis.

• Keywords
• doppler ultrasound of uterine artery, hospitalisation, hospitalization, infant, pertussis, risk factors, surveillance, whooping cough,
• MeSH
• Hospitalization MeSH
• Infant MeSH
• Humans MeSH
• Infant, Newborn MeSH
• Whooping Cough * epidemiology   prevention & control   MeSH
• Pertussis Vaccine MeSH
• Retrospective Studies MeSH
• Risk Factors MeSH
• Pregnancy MeSH
• Vaccination * MeSH
• Check Tag
• Infant MeSH
• Humans MeSH
• Male MeSH
• Infant, Newborn MeSH
• Pregnancy MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic epidemiology   MeSH
• Names of Substances
• Pertussis Vaccine MeSH

AIM: To perform multiple-locus variable number tandem repeat analysis (MLVA) of B. pertussis strains from the collection of the National Reference Laboratory for Diphtheria and Pertussis (NRL/DIPE), National Institute of Public Health (NIPH), Prague. The study strains were isolated from clinical specimens collected mostly in the Czech Republic over a nearly 50-year period from 1967 to 2015 (June). The isolates from three periods characterized by different vaccination strategies and trends in pertussis are compared for genetic diversity and distribution of MLVA types (MT). Based on the results obtained, the suitability for use of MLVA in the analysis of epidemic outbreaks of B. pertussis in the Czech Republic is considered. MATERIAL AND METHODS: DNA samples extracted from B. pertussis strains included in the present study were examined by MLVA using the standard protocol. Data were processed by means of the eBURST algorithm and the calculation of the Simpson diversity index (DI) was used for the statistical analysis. Data were analyzed as a whole and also separately for strains from the three periods: 1967-1980, 1990-2007, and 2008-2015 (June). RESULTS: Fourteen different MT were detected in the study strains, with three of them not being reported before. The most common MTs were MT27 and MT29. MT29 was predominant in 1967-1980 while MT27 was the most prevalent in 1990-2007 and 2008-2015 (June). The DI was the lowest (0.49) in 2008-2015 (June), and comparably higher DIs were calculated for the two previous periods (i.e. 0.667 for 1967-1980 and 0.654 for 1990-2007). CONCLUSION: MLVA revealed a decrease in genetic diversity and shifts in MT distribution of B. pertussis strains isolated from clinical specimens in the Czech Republic from 1967 to 2015 (June). These shifts in the Czech Republic can be characterized as a progressive increase in global MTs at the expense of the locally unique ones. The most common MT, similarly to other geographical areas with long-term high vaccination coverage, is MT27. The results of MLVA of 136 B. pertussis strains can provide a background for using this method in molecular epidemiological analysis of smaller groups of strains.

• Keywords
• Bordetella pertusis - MLVA - population - diversity - adaptation.,
• MeSH
• Bordetella pertussis genetics   MeSH
• DNA, Bacterial analysis   genetics   MeSH
• Genetic Variation genetics   MeSH
• Genotype MeSH
• Humans MeSH
• Minisatellite Repeats genetics   MeSH
• Whooping Cough epidemiology   microbiology   MeSH
• Pertussis Vaccine MeSH
• Retrospective Studies MeSH
• Vaccination statistics & numerical data   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• DNA, Bacterial MeSH
• Pertussis Vaccine MeSH