The epidemiological investigation using purified tuberculin protein was carried out in Fukushima Prefecture in 1965 and 1966. The subjects of this investigation were 856 healthy pupils of junior middle school in Haramachi-City. The skin reaction of purified tuberculin protein prepared from several strains (Ishii--Scotochromogens, Gamou--Nonphotochromogens, P₁₆--Photochromogens, Sato--Rapidd growers) of unclssif ied mycobacteria and human type mycobacteria (H₃₇Rv) measured on the populations of normal healthy pupils. o.15γ of one purified tuberculin protein prepared from unclassified mycobacteria was used as antigen for intracutaneously on the flexion surface of forearm. The same amunt of purified tuberulin protein prepared from tubercle bacillus was injected on the other forearm as the control. For an injection site, the middle one-third part of the forearm was used avoiding the usual site of tuberculin reaction. The results obtained were as follows ; 1) The rate of positive reaction of Ishii was the highest among these four unclassified mycobacteria. 2) The mean value of the diameter of skin reaction by unclassified mycobacteria was almost same size with except rapid grower Sato. 3) Great changes of the coefficients of correlation were found between the human type mycobacteria and unclssified mycobacteria of different kinds.

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An epidemiological study of tuberculosis among students at the University of the Ryukyus was tried here on the basis of the data collected from the survey made among 22, 391 students at the University of the Ryukyus during the period of 10 years between 1956 and 1965. 1. There is an indication that the number of pre-college students suffering from tuberculosis has rapidly been increasing. There are more students who suffer from pulmonory tuberculosis than any other type, and most of them have caught the disease at junior and senior high school age. There is also an indication that the number of students who enter the University of the Ryukyus before recovering from the disease, the number of students who are receiving medication while attending school, and the number of students who leave school for treatment have recently been increasing. I presume that there are surely many patients among applicants for the freshmenat the University of the Ryukyus. 2. The number of student patients gradually decreased during the period of 3 years between 1963 and 1965, and 1965 shows the decrease of 0.66% since 1963. The number of student patients who suffered from the intermediate stage of tuberculosis was a qurter of the total of student patients in 1963, but in 1965 it rapidly decreased to lessthan a tenth of the total. Correspondingly there are more student patients suffering from the elementary stage of tuberculosis. Each year there are more student patients who needed treatment. However, the number of student patients who needed hospital treatment or had to leave school for treatment gradually decreased. The number of student patients who were infected with tuberculosis before entering the University of the Ryukus is, however, 3 to 4 times as many as that of those who were infected with the disease after entering the University. There is a tendency for more student patients to comefrom rural area than from anywhere else. However, the morbidty rate of tuberculosis among studests is from rural area is coming closer to the rate of students from agricultural and fishing villages and towns. Among the total number of students who leave school because of sickness, there are still, however, even though the number is decreasing yearly, more tuberculosis patients than patients of other diseases. Thus, the number of tuberculosis patients at the University of the Rynkyus has been decreasing, and there is an dicationin that a larger number are minor cases of tuberculosis. However, the morbidity rate of tuberculosis among students at this University is still higher than that among Japanese students. 3. Students at the University of the Ryukyus naturally have a positive reaction of tuberculin test since they don't take an inoculation of BCG. The positive reaction rate of a tuberculin test among students at the University of the Ryukyus has gradually been decreasing. I don't think, however, that this phenomenon neccesarily means the decrease of tuberculosis. Like the morbidity rate of tuberculosis, there is an indication that a positive reaction rate of a tuberculin test among students from rural areas has gradually been becoming closer to the rate in agricultural and fishing villages and towns.

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The following points have been discussed on the basis of the survey of new cases among students at the University of the Ryukyus and an epidemiological study of tuberculosis among students at the same school during the period of 10 years between 1956. and 1965. 1. There are no noticeable fluctuation in the number of new TB patients in Okinawa recently. The degrees of their sickness are the intermediate and advanced stages, the calcareous concretion, pleurisy and other types which have symptoms of tuberculosis in the early period of infection and suffer from an acute contraction of the diseases which have a great influence on students at the University of the Ryukyus. There has been an indication, however, that the number of student patients who need recuperation has decreased but that of those who don't have to leave school because of the disease has increased despite the fact that there is hardly any noticeable fulctuations in the number of new TB patients in Okinawa. This phenomenon has resulted from the control of new cases, the prevention of the progress and the control of the active symptom of the disease which have been made after studying the actual condition of the disease through early discovery of the contraction and treatment of the disease with consistent examinations of students. The number of student patients of pleurisy and other types of tuberculosis, however, has been increasing a little and the phenomen on should be carefully studied for the future control of the diseases which will require an inculation of BCG/and improvement of environment. 2. It has been known that there are more TB petients who are infected with the disease during the early period of infection than at other stages. Among our student patients, however, there are more students who are infected with the disease during the period of latter infection than the early period, and there is a phenomenon that some of them have a weaker positive reaction of a tuberculin test. Order to control the disease, however, due concideration should be given both to the early and to the latter period of infection since those who have an intermediate and strong reaction of a tuberculin test are infected with the disease in the early period. 3. There are various causes for new cases of the disease and they are all related to one another. There are more student patients among those who live in rented rooms and othertypes of living accommodations than dormitories where a smaller number of patients are discovered. There are, moreover, many patients among Group C which consists of those students who have financial difficulties. The TB contraction rate of the group is high. There is an indication that students suffer from the disease because of their excessive labor for their part-time jobs and because of other heavy extraculicular activities. Only a few causes are found in dormitories.

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