The distribution of carriers ofStreptococcus pyogenesamong 2,413 healthy children

Nose and throat swabs were collected from 2413 healthy children aged 2 weeks to 14 years and examined for Streptococcus pyogenes . The children came from different social levels in three boroughs in Middlesex. Standardized carrier rates were used to compare the individual effects of age, borough, family age, family size, sex, social class and tonsils on the nose and throat carrier rates. Community life appeared to facilitate the spread of streptococcal infection: young children aged less than 5 who attended nurseries had higher carrier rates than those of the same age who did not attend day-nurseries. The highest nasal carrier rates were found in the 3- and 4-year-old children attending the day-nurseries. The degree of crowding within the community units did not appear to affect the rates. The three boroughs had significantly different carrier rates. Boys were more often carriers than girls. The unstandardized carrier rates were highest in the lowest social class but this could be explained by the differences in the age, sex and borough distribution of the children sampled in the three social classes, and by the fact that tonsillectomy was, on the average, undertaken later in the lower social classes than in the higher. When these factors were allowed for by standardization, there was no residual difference which could be attributed to social class or housing. Children with tonsils were more often nose and throat carriers than children who had had their tonsils removed; this was true for all ages, for each of the three boroughs and in each social class. We are indebted to the Area Medical Officers in Enfield, Southgate and Willesden for their co-operation in the planning of the survey and to the staff in the schools, day-nurseries and clinics where the swabbing was carried out. We are most grateful to Dr P. Armitage for help with the statistical methods and to Miss Eileen Cole for much help with the computing.