Seasonal incidence of streptococcal carriers in school children in Korea and its correlationship with streptococcal diseases
Diseases caused by direct invasion or sequal of group A beta hemolytic streptococcal infection are quite common in young children. Physicians have paid careful attention to this streptococcal infection particularly in regard to prevention and special management, because sometimes rheumatic fever causes serous cardiac damage and some cases of acute golmerulonephritis transform to chronic state. The incidence of streptococcal illness is variable according to season and it seems to be related to seasonal changes of carriers of group A beta hemolytic
Grover et al(1965) pointed out that the peak incidence of positive culture rate of group A beta hemolytic strepotococcus in healthy children was noted from January to June and lowest incidence in August and September. Cornfield and Hubbard(1961)
also reported the highest incidence of streptococcal carrier rate in Spring. Stillerman and Bernstein(1961) found the fact that the incidence of streptococcal carrier rate in healthy children was the highest between March and April and the seasonal incidence of streptococcal diseases paralleled to the seasonal carrier rate of the children.
Such seasonal variations in the carrier rate are different in one country from another, but there is no known report on the study of the changing patterns of seasonal streptococcal carrier rate in Korean children.
In this study, seasonal incidence of group A beta hemolytic streptococcal carriers in healthy children was investigated through nasopharyngeal and throat cultures and comparative study of seasonal carrier rate of streptococcus and diseases that relate to it was also studied.
164 school children(2 cases) were subjects of this study to obtain seasonal incidence of streptococcal carriers. Nasopharyngeal and throat cultures were performed once a month with each class of children alternately for one year excluding January and April. Specimens were obtained from the nasopharynx and throat with sterilized cotton applicators with 1 drop of nutrient broth to avoid dryness. These specimens were inoculated on sheep blood agar plates and symbiosis cultures with Staphylococcus aureus were performed on evey cultrue plate to
identify Hemophilus influenzae colonies. All these culture plates were incubated for 48 hours and group A beta hemolytic streptococci were identified by a bacitracin disc sensitivity test and hemolysis test with sheep blood. Optochin tests and Moller's capsule stains for pneumococcus, coagulase tests with human plasma for Staphylococcus aureus and symbiosis cultures for Hemophilus influenzae helped finding other pathogenic prgamos,s/
225 patients, hospitalized from April 1958 to March 1966 at Severance Hospital under the diagnosis of acute glomerulonephritis(146), rheumatic fever(64) and scarlet fever(15) were investigated by monthly analysis. The following results were obtained:
1. Monthly incidence of group A beta hemolytic streptococcal carriers:
In July and August, there was no positive case in nosopharyngeal and throat cultures but in September, some positive cases(nasopharynx 4.9%, throat 3.7%) were found. Positive case incereased in October(nasopharynx 12.8%, throat 6.1%) until it reached it's peak in November (15.2% for nasopharynx, 16.5% for throat culture) and decreased in December(nasopharynx 5.0%, throat 8.8%). In February and March, it showed the lowest culture rate but slightly increased carrier rates were again noted in May and June(2.6% and 3.8% respectively for throat).
2. Incidence of positive culture cases among carriers:
Of 164(total) cases, 37 children(22.6%) had one or more positive cultures during the study period, and 35 cases(94.6%) among 37 carriers had only one positive culture. The remainder had 2 positive cultures.
3. Positive carrier rate by culture site:
Of carriers, 19 cases(51.4%) were poistive from throat swabs and 12 cases(32,4%) from nasopharnx. 8 cases (21.6%) were positive cultures from both nasopharynx and throat.
4. Antistreptolysin 0 titer in carriers:
only 9 cases among 20 carriers, showed significantly high ASO titers within 2 months after positive bacterial cultures, but 13 cases(72.2%) among 18 carriers showed high ASO titer within 1 month 1 month after positive cultures.
5. Monthly distribution of streptcococcal diseases and streptcococcal carriers:
Patients with streptcoccal diseases were frequently found from September to January and especially in October(20% of all cases) and November(17.3% of all cases). The peak incidence decreased until March and April(3.1% and 3.6% respectively), which is the period of lowest incidence. Then it increased again in May and June (8.0% and 7.6% respectively) and it is probable that the seasonal patterns of streptococcal diseases parallel the seasonal carrier rate of group A beta hemoytic streptococcus.