台灣乳牛場結核病牛難以根除之原因探討

Difficulties in Eradication of Tuberculosis Infected Cows from the Infected Dairy Herds in Taiwan

葉坤松(Ku-Song Yei) ； 吳永惠(Yeong-Huey Wu) ； 廖明輝(Ming-Huei Liao) ； 劉宏仁(Hung-Jen Liu) ； 張清棟(Ching-Dong Chang) ； 蕭終融(Chung-Jung Shiau)

《臺灣獸醫學雜誌》 30卷1期 (2004/03) Pp. 56-63

https://doi.org/10.7009/TVJ.200403.0056

摘要

對台灣地區結核病感染場（前次ITT檢驗有陽性牛隻出現之乳牛場）2場215頭ITT陰性乳牛，每3個月1次連續4次，同時進行皮內結合菌素檢驗（intradermal tuberculin test; ITT）、迦瑪干擾素檢驗（Gamma Interferon Test；IFN-γ檢驗）和雙引子聚合酶鏈鎖反應（duplex polymerase chain reaction；以下簡稱PCR）等3種檢驗法，結果在4次檢查中，全部牛隻ITT均呈陰性，血液IFN-γ和PCR檢驗則分別有13.0%（28/215）和7.9%（17/215）有1-4次呈現陽性對該17頭ITT陰性而血液PCR陽性之牛隻，採鼻黏液和乳汁行PCR，結果鼻黏液有23.5%（4/17）呈現陽性，乳汁則均呈陰性。另對5場72頭ITT陽性乳牛，採血行IFN-γ和PCR檢驗，採鼻黏液和乳汁行PCR，以及採縱膈和咽背淋巴結行牛結核桿菌（Mycobacterium bovis）分離，結果血液IFN-γ和PCR檢驗呈陽性者分別有95.8%（69/72）和86.1%（62/72）；鼻黏液和乳汁之PCR呈現陽性者分別有66.6%（48/72）和38.6%（17/44）；在ITT、血液IFN-γ和PCR檢驗呈陽性之牛隻中分別有68.1%（49/72）、68.1%（47/69）和67.7%（42/62）可由淋巴結分離到牛結核桿菌。另外，由ITT陽性場之10位牛群管理人、10隻犬、4隻貓和10隻鼠採血行PCR檢驗，結果僅管理人3位（30%）呈現陽性。由以上結果，我們推論在結核病感染場僅行ITT檢驗，不易將感染牛全部檢出，而ITT陽性牛及ITT陰性但血液PCR陽性之牛隻可介由鼻排泄物傳播牛結核桿菌給健康牛，或介由生乳之餵食傳染給哺乳牛，此可能是感染牛場結核病難以清淨化之主因。

關鍵字

牛結核病 ； 雙引子聚合酶鏈鎖反應 ； 迦瑪干擾素檢驗 ； 皮內結核菌素檢驗

並列摘要

Using intradermal tuberculin test (ITT), gamma interferon test ( IFN-γ test ) and duplex polymerase chain reaction (duplex PCR) for tuberculosis, a total of 215 ITT negative cows from two infected diary herds, which have had ITT positive cows in the last ITT test, were continuously examined four times at interval of three months. The results showed that all 215 cows were negative reactions on ITT in four times of examinations, but 13.0% (28/215) and 7.9% (171/215) cows were positive on one to four times of IFN-γ test or duplex PCR, respectively. Using the duplex PCR, the nasal mucus and milk were examined on the 17 cows, which were negative for ITT but positive for duplex PCR of blood samples. The results revealed that 23.5% (4/17) cows were positive on the nasal mucus samples, but all the milk samples were negative. On the other hand, the blood, nasal mucus and milk samples of 72 ITT positive cows from five other infected farms were examined by above methods, and their mediastinal and retropharyngeal Iymph nodes were sampled for Mycobacterium bovis isolation. The results showed that 95.8% (69/172) and 86.1% (62/72) cows were positive on blood samples for tuberculosis by IFN-γ test and duplex PCR, respectively. Sixty six point six percent (48/72) and 38.6% (17/144) cows were positive for tuberculosis by duplex PCR on nasal mucus and milk samples, respectively. M. bovis were isolation from 68.1% (49/72) ITT, 68.1% (47/69) IFN-γ test and 67.7% (42/62) duplex PCR positive cows, respectively. Besides, blood samples collected from 10 herdsmen, 10 dogs, 4 cats and 10 rats in these seven infected diary herds were examined by duplex PCR; only 30.0% (3/10) herdsmen were positive for M. bovis. From the above results, we concluded when only ITT were used, the infected cows would not be thoroughly eliminated from the infected herds. The ITT positive or PCR positive but ITT negative cows could easily spread M. bovis through their nasal discharge or raw milk to the ITT negative cows or nursing calves. This might be the most important causes of difficulty in eradicating tuberculosis from the infected diary herds.

並列關鍵字

Bovine tuberculosis ； Dupfex pofymerase chain reaction ； Gamma interferon test ； Intradermal test