Japanese Journal of Veterinary Research;第1巻 第3號


北海道に於ける有反應無病巣牛に關する細菌學的研究 : II. 昭和 27 年度の檢索成績

平戸, 勝七;清水, 龜平次

Permalink : http://hdl.handle.net/2115/11354
JaLCDOI : 10.14943/jjvr.1.3.148


In Hokkaido, tuberculin testing of cattle was first started in 1903. At that time, 8,000-20,000 cattle were being tested annually, of which hundreds of head gave postive reactions. The reactors were slaughtered in every case and as the results of these procedures, their number decreased year by year. Then the average number of reactors became as few as about fifty head, that is, only 0.1-0.2% of all tested cattle (Fig. 1). On the other hand, since 1931 many positive reactors have been noticed at autopsy to show no signs of tuberculous lesions and this phenomenon became more remarkable (Fig. 2). Since 1948 the method of the intradermal tuberculin test has been adopted; the number of no-lesion reactors in Hokkaido increased more and more and in 1950-1951 it had reached to 80-100% of all reacting cattle. Accordingly, since several years ago, the authors have carried out bacteriological studies on this curious phenomenon and as the result they could detect three cases of human type tubercle bacilli infection from 21 tuberculin positive-reacting cattle which showed no tuberculous lesions on autopsy as has already been reported in "Veterinary Research" No. 1. Following this report, also in 1952,the writers carried out the same investigations on the causative agents of the no-lesion reactors in Hokkaido. Materials were re-collected and detailed investigations were performed from both the bacteriological and the pathological standpoints. Results obtained are summarized as follows. (1). In 1952 about 70,000 cattle were tested in various districts of Hokkaido, only 29 head of which reacted. Fourteen head of these were examined. Tuberculous lesions were macroscopically detected in only 1 case, No. 28-soy-bean-sized tubercle in bronchial lymph nodes. The others showed no tuberculous lesions even in histological investigations. These were so-called no-lesion reactors (Table 1). (2). Cultivation and guinea pig inoculation experiments were performed in 12 of those fourteen cases. Mycobacterium tuberculosis was detected in 3 cases. The bacilli were cultivated from the materials of retropharyngeal (No. 23,No. 26) and bronchial lymph nodes (No. 28) respectively. The number of cultivated bacilli from about 1.5cc. of dense emulsion of materials was very small as few as 1 or 2,except No. 28 which showed macroscopical lesions (Table 2). After all, the authors could not certify any instance of the infection with bovine type tubercle bacilli. (3). The woman caretaker who had looked after No. 23 calf suffered open pulmonary tuberculosis several years ago. Tubercle bacilli could be isolated from her sputum as well as from lymph node of the calf at the same time (Table 3,4). (4). Several biological characters and pathogenicity for rabbits of these isolated bacilli were studied. As the result of examination, all of these tubercle bacilli were found to be identical with human type (Table 3,4). (5). Moreover, inquiries were made regarding tuberculous persons associating with the tuberculin-positive-reacting cattle. It was consequently found that half of these cattle had been in contact with tuberculous persons directly or indirectly for various periods of time. Especially, cattle Nos. 23,26 and 28,from which human type tubercle bacilli were isolated, had been in care of tuberculous persons for several months or years (Table 1). (6). From the above-mentioned results and the previous report, the authors are confident that not a few cases of tuberculin-positive cattle in Hokkaido are inflicted with the infection or are influenced by human type tubercle bacilli. Accordingly, it is urgently recommended that all cattle be strictly isolated from tuberculous persons.