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; 11 th Internation Bordetella Symposium; 2016

PERTUSSIS EPIDEMIOLOGY IN ARGENTINA OVER 2005-2015: TRENDS BY AGE GROUP ANDSTATUS OF VACCINATIONBOTTERO D1; MARTIN AISPURO P1; FLORES D1; HOZBOR D11Laboratorio VacSal. Insittuto de Biotecnología y Biología Molecular. FCE-UNLP.CONICETObjectiveDespite good vaccination coverage in Argentina, pertussis is still considered a heath problem. Here we describethe most relevant epidemiology trends of pertussis in Argentina during 2005-2015 and discuss possible reasonsfor the detected increase.MethodsProportion of cases by age, patient immunization status and immunization coverage rate evaluated at the ArgentineanPertussis Reference Laboratory are reported. CDC criteria were used for pertussis diagnosis. B. pertussisisolates obtained in this period were characterized by ptxP variant and prn and ptx genotypes, comparisonswith vaccine strains are included.ResultsFrom 19,817 clinical specimens obtained from patients with pertussis clinical signs, 22.1% cases had a positivelaboratory 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 obtainedbefore 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 andstate 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 invaccine application as well as low vaccination coverage. Molecular characterization of the recovered B. pertussisisolates (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 isolateshave ptxP3, prn2 and ptxA1.ConclusionsPertussis is an important problem for public health in Argentina. Delay in vaccine application, low coverage insome regions and divergence between vaccine strains and local isolates could explain this situation.