Scarlatina Immunity In Hong Kong

1. In Hong Kong, where scarlet fever is extremely rare, the Dick reactions of a random sample of 921 Chinese were ascertained. Positive reactions were obtained in 19·1 per cent. The distribution of positive reactors in different age groups is recorded; it bears a general similarity to those recorded by various observers in Europe and the U.S.A. 2. A haemolytic streptococcal carrier rate of 6·6 per cent, was determined by nasopharyngeal swabbing of 1600 Hong Kong Chinese. The frequency of haemolytic streptococci was higher during the cooler months of the year and among the younger age groups. 3. Erythrogenic toxin production and fibrinolytic activity were demonstrated in a number of the strains of streptococci isolated from apparently normal throats. 4. The significance of these findings is discussed.