Molecular epidemiology of Mycobacterium tuberculosis COMPLEX (MTC) and Mycobacterium avium subsp. paratuberculosis in peri-urban and urban dairy farms of Guwahati
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Date
2022
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College of Veterinary Science, Assam Agricultural University, Khanapara Campus
Abstract
Bovine tuberculosis (bTB) and paratuberculosis (JD) are the two most common diseases caused by pathogenic mycobacterial species in livestock.Bovine tuberculosis is a chronic type of neglected zoonotic disease caused by Mycobacterium bovis which is distributed worldwide. The present study was carried out from December, 2020 to November, 2021 and envisaged to collect the baseline data from peri-urban and urban dairy farms of Guwahati following questionnaire method and molecular detection of Mycobacterium tuberculosis complex (MTC) and M. avium subsp. paratuberculosis (MAP) using specific primer on the targeted DNA. Farms (36) were identified from 12 different locations and the GPS coordinates of latitudes and longitudes of the selected farms were recorded. A total of 360 animals (10 from each farm) were initially screened by SICCT to determine the prevalence of bTB. PCR was carried out from 620 samples for detection of bTB (milk: 360, nasal swab:150 and tissue samples from slaughtered cattle: 110) and for detection of paratuberculosis, 220 samples (milk:100; intestine: 60 and fecal: 60) were targeted. Baseline data revealed that 61.11% respondents were of illiterate, 66.67% had no awareness about bovine tuberculosis and 41.67% consumed unprocessed milk and milk products. SICCT depicted 38 cattle to be positive reactors for bTB, yielding the overall prevalence of 10.55%. Age group 5 years and above was found to be more susceptible for bTB (17.18%). PCR of 16 (4.44%) milk samples showed presence of Mycobacterium genus specific hsp65 gene and two milk samples revealed the presence of MTC DNA by amplifying the IS6110 sequence. Presence of hsp65 gene was detected only in 1 (0.6%) nasal swab whereas, out of 110 tissue samples, 24 (21.81%) were detected as genus Mycobacterium by the presence of hsp65 gene in PCR. IS6110 & IS1081 PCR confirmed the presence of MTC DNA in tissue samples 15 (13.36%) and 18 (16.36%), respectively. Speciation of MTC DNA showed 8 (7.27%) and 5 (4.54%) by amplifying 500 bp fragments and RD4 region, respectively. Most of the MTBC positive samples in conventional PCR, were detected as positive by real-time PCR targeting insertion element IS6110 and IS1081 with Ct values ranging from 13.45 to 34 and 12.88 to 33, respectively. In molecular detection of paratuberculosis, 7/60 (11.66 %) intestinal samples and 1/60 (1.66%) fecal samples showed the presence of both hsp65 and MAP specific IS900 gene and their identities were confirmed by sequencing. The study highlighted the wide spread prevalence of bovine tuberculosis and paratuberculosis in peri-urban and urban dairy farms and it is of utmost importance to undertake a comprehensive epidemiological study and implementation of one health approaches for strategic control and prevention of bTB and MAP.