[Tuberculin sensitivity among school children in Niigata Prefecture, Japan]

Tuberculin sensitivity was studied in 668 apparently healthy schoolchildren six to seven years of age vaccinated B.C.G. before the age of one. Sensitivity was assessed using the standard dose of PPD and reactions with an area of erythema of 10 mm diameter or more were considered positive. The results were as follows: 1) The frequencies of tuberculin-positive children were 97 (31.3%) of 310 subjects in the fishing area, 21 (9.9%) of 213 in the farming area, and 35 (24.1%) of 145 in the intermediate zone. 2) Prevalences of the positive children by obesity index were 28 (36.8%) of 76 in the large, 72 (24.5%) of 294 in medium, and 53 (17.8%) of 298 in the small, and the decreasing tend in frequencies among these three classes by obesity index were statistically significant (p < 0.01). 3) Gender differences in frequency of tubereulin-positive children were not clearly detected when a comparative study grouped by obesity index and area was carried out. These observations suggest that tuberculin sensitivity in children may be influenced by the size of body mass and also characteristic factors, including diet, in their residential districts.