The use of PCR technique in the identification of Mycobacterium species responsible for bovine tuberculosis in cattle and buffaloes in Pakistan.

Bovine tuberculosis is one of the important diseases of dairy and wild animals. The disease is prevalent all over the world, though developed countries have tremendously reduced the prevalence through eradication campaigns. The prevalence of disease in Pakistan on the basis of tuberculin testing or culture isolation of the organism has been reported previously. It is, however, important to use the latest diagnostic tools, i.e. PCR to confirm the type of Mycobacterium infecting the animals in Pakistan. Therefore, the present study was carried out to assess the utility of direct PCR on milk samples and nasal swabs to confirm the type of Mycobacterium infecting the animals. This study was carried out on 215 cattle and buffaloes of more than 2 years of age present at two livestock farms. The tuberculin results showed 22.5% prevalence at one farm and 25.9% at the other with an overall prevalence of 24.7%. The 92.5% of milk samples and/or nasal swabs showed positive PCR for Mycobacterium genus, 86.8% for Mycobacterium tuberculosis complex and 77.4% for Mycobacterium bovis. The M. bovis by PCR was detected in 13.2% of milk samples, 24.5% of nasal swabs and 39.6% of both milk samples + nasal swabs. The results suggested that there are 60% higher chance for a nasal swab to yield a positive PCR for M. bovis than the milk sample. It can be concluded from the present study that tuberculin testing is a useful method in studying the prevalence of disease as the PCR for Mycobacterium genus was positive in 92.5%, M. tuberculosis complex in 86.8% and Mycobacterium bovis in 77.4% cases.

Prevalence of paratuberculosis in water buffaloes on public livestock farms of Punjab, Pakistan.

The present study had the goal to assess the prevalence of paratuberculosis in 4 public livestock farms of the Punjab (Pakistan). It included 627 total animals of more than 2-year-old tested by Avian Tuberculin, i.e., Purified Protein Derivative. The results of the PPD test were confirmed by indirect ELISA and by Ziehl-Neelsen (ZN) test. An overall prevalence of 1.3% was recorded. The values were between 0.0% and 3.03%. The results of odds ratio suggested that there are 2.18 time's higher chances of disease when body weight of buffaloes is less than 500 kg; 1.65 times in  dry  than  lactating  animals;  2.58  times  when  small  ruminants  are  present;  and  1.19  times when cattle are absent. The total positive buffaloes observed by Avian PPD were 12, although only 10 were then confirmed by ELISA, and 8 by ZN faecal microscopy. The relative sensitivity and  specificity  of  Avian  PPD  by  considering  ELISA  as  standard  test  were  80.0%  and  89.47%, respectively.  Similarly,  the  relative  sensitivity  and  specificity  of  the  ZN  faecal  test  were  70.0% and 97.37%, respectively. The relative sensitivity and specificity of Avian PPD by considering ZN faecal test as standard were 100% and 90%, respectively. Among haematological parameters, platelets significantly decreased and MCH increased in paratuberculosis positive animals. It can be concluded that ELISA may be used as a screening test in future studies for paratuberculosis, tuberculin testing can be used when the ELISA is not affordable to assess the disease situation at the farm; while ZN microscopy, being it a non-invasive test, is a better option than skin testing.