Bordetella pertussis: clinical and molecular trend in the decade 2010-2019

Pertussis or whooping cough is a bacterial disease that consists in severe infection of the respiratory tract mainly caused by Bordetella pertussis. The disease affects all ages, but mainly affects children under the age of 5 years. In Italy, the introduction of acellular vaccine against whooping cough in 1995 has made it possible to significantly reduce cases of disease and deaths due to the disease itself: the data for 2010- 2013 indicate a drop in the burden of disease of 97.6%. Unfortunately, the number of cases of whooping cough is currently increasing in children, adolescents and adults. There are basically three reasons for this phenomenon. First of all, in Italy, as in the rest of Europe, there is a drop in vaccination coverage. Vaccination coverage for whooping cough is below 95% in all age groups monitored (24, 36 months and 6, 16 and 18 years). It is also known that the immunity resulting from both vaccination and naturally contracted disease is not long-lasting. A third explanation for the increase in pertussis cases is the selective pressure induced by vaccination. The use of pertussis vaccines may have selected mutated bacteria that express antigens not included in the available vaccines. The mutation of one or more of these antigens, caused by immunological pressure, could play a decisive role in the increase in cases of whooping cough in general and also in subjects already properly vaccinated. My study aims, on the basis of data collected from 2010 to 2019 by the regional reference center of invasive bacterial diseases, to analyze the epidemiology of pertussis infection in the paediatric population of Tuscany, with the aim of defining some of the main risk factors for both the occurrence of the infection and for the occurrence of serious infections that require hospitalization. In detail, we will analyse the epidemiological characteristics of the subjects presenting the infection in order to deduce the best vaccination strategy. Through the knowledge of the incidence of whooping cough in preterm births we could obtain useful indications to be able to standardize the national vaccination calendar, even for this particular group of children. Finally, my study aims at studying the strains of B. pertussis that circulate in Tuscany. In fact, we want to understand if in Tuscany, as in most of Europe, new varieties of B. pertussis are emerging.