Epidemiology and Infection

Original Papers

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

M. I. McDONALDa1a2 c1, R. J. TOWERSa1, R. ANDREWSa1, N. BENGERa1, P. FAGANa1, B. J. CURRIEa1 and J. R. CARAPETISa1

a1 Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory Australia

a2 University of Melbourne Department of Paediatrics, Royal Children's Hospital, Melbourne, Victoria, Australia

Abstract

Prospective 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 were emm sequence and pattern-typed using standard laboratory methods. There were 531 household visits; 43 different emm types and subtypes (emmST) were recovered. Four epidemiological patterns were observed. Multiple emmST 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 of emmST was brief, usually <2 months. The epidemiology of GAS in these remote Aboriginal communities is a highly dynamic process characterized by emmST diversity and turnover.

(Accepted April 03 2007)

(Online publication May 31 2007)

Correspondence:

c1 Author for correspondence: Dr M. I. McDonald, Menzies School of Health Research, PO Box 41096, Casuarina, 0811, NT, Australia. (Email: malcolm.mcdonald@menzies.edu.au)

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