TUBERCULOSIS: in animals and humans

 May 3, 2011 : Muhammad Yasin Tipu

According to an estimate, Pakistan has a population of about 34.3 million cattle and 30.8 million buffaloes. Among the diverse bovine pathogens, mycobacteria are highly significant, especially among farm animals. Apart from mortality, it is estimated that the animals affected with tuberculosis lose 10 to 25 percent of their productive efficiency. Bovine tuberculosis is not only a threat to animals, but it is also a zoonotic and public health problem. Mycobacterium bovis, the cause of bovine tuberculosis, and mycobacterium tuberculosis, the cause of classical human tuberculosis, are genetically and antigenically very similar and cause identical clinical disease in humans. The disease is a major problem and causes more causalities worldwide than Malaria and HIV.
Tuberculosis is present worldwide with an extremely high prevalence in Asian countries, where 60 to 80 percent of the children below the age of 14 years are infected. The largest number of cases occurs in the Southeast Asian region, which accounts for about 33 percent of the cases globally. The bovine type may cause as high as 25.8 percent of tuberculosis in human beings.
In Europe, according to reports, mycobacterium bovis is the cause for almost 50 percent of cervical lymph adenitis cases in children. In addition, it is the major cause of human gastrointestinal tuberculosis in the developing countries, where bovine milk is not pasteurised before use. In Pakistan, however, tuberculosis is prevalent at epidemic proportions in both human beings and animals. Unfortunately, there are various aspects of this disease that still need to be analysed. It is hypothesised that bovine tuberculosis may be prevalent in Pakistan due to the use poorly pasteurised milk. Certainly, the existing situation calls for a comprehensive programme to address this problem in order to save the livestock, and particularly the human population at risk.
The key factors that can control tuberculosis are rapid detection, adequate therapy and contact tracing to arrest further transmission. Bovine tuberculosis infection in cattle is usually diagnosed in the animal on the basis of delayed hypersensitivity reactions. But after the animal dies, it is diagnosed through a post-mortem examination, and histopathological and bacteriological techniques. Bacteriological examinations may comprise the demonstration of acid-fast bacilli by microscopic examination (provides presumptive confirmation), and the isolation of mycobacteria on selective culture media and their subsequent identification by cultural and biochemical tests. Culture is gold standard, but a lot of time is required for this slow-growing organism. Serodiagnosis of tuberculosis also has many limitations
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