The dynamic nature of group A streptococcal epidemiology in tropical communities with high rates of rheumatic heart disease

Abstract

SUMMARYProspective surveillance was conducted in three remote Aboriginal communities with high rates of rheumatic heart disease in order to investigate the epidemiology of group A β-haemolytic streptococci (GAS). At each household visit, participants were asked about sore throat. Swabs were taken from all throats and any skin sores. GAS isolates wereemmsequence and pattern-typed using standard laboratory methods. There were 531 household visits; 43 differentemmtypes and subtypes (emmST) were recovered. Four epidemiological patterns were observed. MultipleemmST were present in the population at any one time and household acquisition rates were high. Household acquisition was most commonly via 5- to 9-year-olds. Following acquisition, there was a 1 in 5 chance of secondary detection in the household. Throat detection ofemmST was brief, usually <2 months. The epidemiology of GAS in these remote Aboriginal communities is a highly dynamic process characterized byemmST diversity and turnover.