PERTUSSIS EPIDEMIOLOGY IN ARGENTINA OVER 2005-2015: TRENDS BY AGE GROUP AND STATUS OF VACCINATION

BOTTERO D.; MARTIN AISPURO P ; FLORES D; HOZBOR D

Simposio; 11th International Bordetella Symposium; 2016

Objective: Despite good vaccination coverage in Argentina, pertussis is still considered a heath problem. Here we describe the most relevant epidemiology trends of pertussisin Argentina during 2005-2015 and discuss possible reasons for the detected increase.Methods: Proportion of cases by age, patient immunization status and immunization coverage rate evaluated at the Argentinean Pertussis Reference Laboratory are reported.CDC criteria were used for pertussis diagnosis. B. pertussis isolates obtained in this period were characterized by ptxP variant and prn and ptx genotypes, comparisons with vaccine strains are included.Results: From 19,817 clinical specimens obtained from patients with pertussis clinical signs, 22.1% cases had a positive laboratory result. Two outbreaks were detected in 2005 and in 2011 with 5.7 and 8.3 cases per 100,000 inhabitants, increasing 46% in 6 years. Though a clear increase was observed at all age groups compared to data obtained before 2003, children under 6 months had the highest proportion of pertussis cases during the studiedperiod. From the total patients with positive laboratory results, 68% had complete data about patient's age and state of vaccination, and 42% of them were less than 6 months old and had received less than 3 vaccine doses. Though pertussis vaccination coverage is adequate for the total country, there are some regions with delay in vaccine application as well as low vaccination coverage. Molecular characterization of the recovered B. pertussis isolates (287 isolates) revealed a genotypic divergence between them and the strains used in vaccine production: while vaccine strains contain pxP1 or 2, prn1 or 7 and ptxA2 or 4 alleles, the majority of local isolates have ptxP3, prn2 and ptxA1.Conclusions: Pertussis is an important problem for public health in Argentina. Delay in vaccine application, low coverage in some regions and divergence between vaccine strains and local isolates could explain this situation.