Bovine tuberculosis in intensive dairy operations of Punjab: Longitudinal comparative study on prevalence and the associated risk factors

Bovine tuberculosis (Bt) is a chronic, contagious disease caused by Mycobacterium bovis and is still highly enzootic and zoonotic problem in countries like India. The herd eradication campaigns were started in India based on single intradermal test using bovine tuberculin purified protein derivative (PPD), and culling of reactors. In the present study a total, 15,737 animals were tested for Bt using single intradermal tuberculin test in different parts of Punjab (India) over 23-year period (1986–2009). A total of 847 animals showed positive reaction with overall prevalence being 5.38% (Range 1.53 to 13.91% in different years). The epidemiological history of animals (n=5208) screened in last eight years (2002–2009) was recorded and risk factor analysis for species, age and sex was made. Bt prevalence was found significantly higher (χ² test; P<0.01) in cattle (5.02%) as compared to buffaloes (3.08%). Risk of disease was found higher (1.66 times) in cattle as compared to buffaloes as revealed by risk ratio and odds ratio. Age wise, disease prevalence was non-significantly higher (χ²=3.37; p=0.499) in animals of higher age group indicating chronic nature of disease. In each sex group, there was no significant influence of age for positivity. Similarly, at each age group there was no significant association between sex and test positivity. In view of the above, under the scenario of extensive cross breeding programs being practiced, control of tuberculosis in high yielding cross breed animals need special emphasis.