This was a prospective, cross-sectional, observational study conducted among the human and animal population simultaneously. The study was conducted for the period of three years starting from January 2009 to December 2011 to determine the prevalence and risk factors associated with human and bovine tuberculosis.
a) Selection of study population
In this study, 3085 patients who were admitted in Dhobaura Health Complex and 649 cattle registered in Dhobarua Upazila Veterinary Hospital were selected. A detailed history, age, sex were recorded in a questionnaire from disease register maintained by the Upazila Tuberculosis and Leprosy Control Unit, Health Complex, Veterinary Hospital, human residence and animals owners houses of Dhobaura upazila in Mymensingh.
b) Diagnoses of cases The diagnosis of human tuberculosis was based on history, clinical examination, BCG test and Xray, Sputum examination, tuberculin test, lymph node biopsy and histological or cytological examination at Dhobaura Health Complex, Mymensingh; Mymensingh Medical college Hospital, Mymensingh; Department of Medicine, Bangladseh Agriculturl University, Mymensingh, Bangladesh. Acid fast bacilli were demonstrated in the section of chemical and mediastinal lymphnodes by acid fast staining. Bovine tuberculosis was diagnosed based on history, clinical findings, complete physical examination, Caudal fold tuberculin (CFT) test at Dhobarua Upazila Veterinary Hospital, Mymensingh and Department of Medicine, Bangladseh Agriculturl University, Mymensingh, Bangladesh. To determine the seasonal influence on the clinical prevalence of tuberculosis in human and animals, the data were collected in different months of the year.
c) Caudal fold tuberculin (CFT) test
This is the primary screening test to identify animals potentially infected with bovine TB. The test measures the immune response to Mycobacterium bovis, the causative agent of bovine TB. The test was performed by intradermal injection of 0.1 ml bPPD with a hypodermic syringe in the skin of the caudal fold (the fold of skin at the base of the tail). If the animal was exposed to mycobacteria, the immune system responded with inflammatory cells at the injection site to cause swelling and/or discoloration of the skin. After 72 hours, inspection and palpation of the injection site was done to evaluate for a response. Marked edematous swelling, reddening at the injection site classified the animal as a responder. If no response was noted, the animal was classified as CFT test-negative. Responder animals were further tested with CCT test for confirmation.
d) Statistical analysis
The collected data was compiled, tabulated and analyzed in accordance with the objectives of the study. The approximate percentage was calculated for each parameter. The questionnaire-based data was processed in Microsoft Excel and analyzed in SPSS. The z-test for proportions was done to find out the relationship of different factors on the occurrence of tuberculosis in human and cattle. Where Significance was determined in terms of age, sex, year and month of occurrence at 5% level.