A longitudinal study of Lancefield group A streptococcus acquisitions by a group of young Dunedin schoolchildren.

Paired saliva and pharyngeal cultures obtained on nine occasions over a 27-month period from a group of 103 young Dunedin schoolchildren were tested for beta haemolytic Lancefield group A streptococci. Approximately 20% of the 858 pharyngeal cultures and 5% of the saliva cultures were positive. Although group A streptococci were isolated at least once from 59 (57.3%) of the subjects, only seven cases of clinically apparent group A streptococcus pharyngitis were detected at the time of specimen taking. The study has shown that pharyngeal acquisitions of group A streptococci occur frequently in some young schoolchildren. Carriage of small numbers of group A streptococci in the absence of clinical symptoms of infection was common and in ten children the same type of group A streptococcus was consistently recovered from pharyngeal cultures over periods of more than 12 months. It remains unclear why some children do not seem to so readily acquire group A streptococci, while others develop serious delayed sequelae to these infections.