Tuberculin skin test among medical college students

The incidence of active tuberculosis in Japan has markedly decreased in the past few decades. It is also reported that the prevalence of tuberculosis infection in young population has been decreasing in accordance with the decline in the overall occurrence of tuberculosis. The above mentioned facts indicate that the younger population has a greater risk of developing tuberculosis once exposed to tuberculosis infection. Actually, the epidemics of tuberculosis among the adolescent population have often been reported in recent years. We performed a tuberculin skin test on our medical college students, who might be exposed to tuberculosis infection during their student clinical internship, in order to obtain the information about their present status of reaction to the tuberculin skin test. The data obtained from students between 18 and 25 years old were analyzed using Student's t test and Kruskal-Wallis's method. The mean size of erythema in the group of 23, 24 and 25 years old were significantly greater than that in the group of 20, 21 and 22 years olds. Similarly the latter was significantly greater than that in the group of 18 and 19 years olds. Furthermore, it was proven by the Kruskal-Wallis's method that the older a group was, the greater the chance of a large erythema. One explanation for this fact might be a decrease in the prevalence of tuberculosis infection in the younger generation as described above. Another explanation seems to be related to the revision of the Tuberculosis Prevention Law in 1974.(ABSTRACT TRUNCATED AT 250 WORDS)