Molecular epidemiology of bovine tuberculosis in Northern Ghana identifies several uncharacterized bovine spoligotypes and suggests possible zoonotic transmission.

Objective: We conducted an abattoir-based cross-sectional study in the five administrative regions of Northern Ghana to determine the distribution of bovine tuberculosis (BTB) among slaughtered carcasses and identify the possibility of zoonotic transmission. Methods: Direct smear microscopy was done on 438 tuberculosis-like lesions from selected cattle organs and cultured on Lowenstein-Jensen media. Acid-fast bacilli (AFB) isolates were confirmed as members of the Mycobacterium tuberculosis complex (MTBC) by PCR amplification of IS6110 and rpoß. Characterization and assignment into MTBC lineage and sub-lineage were done by spoligotyping, with the aid of the SITVIT2, miruvntrplus and mbovis.org databases. Spoligotype data was compared to that of clinical M. bovis isolates from the same regions to identify similarities. Results: A total of 319/438 (72.8%) lesion homogenates were smear positive out of which, 84.6% (270/319) had microscopic grade of at least 1+ for AFB. Two hundred and sixty-five samples (265/438; 60.5%) were culture positive, of which 212 (80.0%) were MTBC. Approximately 16.7% (34/203) of the isolates with correctly defined spoligotypes were negative for IS6110 PCR but were confirmed by rpoß. Spoligotyping characterized 203 isolates as M. bovis (198, 97.5%), M. caprae (3, 1.5%), M. tuberculosis (Mtbss) lineage (L) 4 Cameroon sub-lineage, (1, 0.5%), and M. africanum (Maf) L6 (1, 0.5%). A total of 53 unique spoligotype patterns were identified across the five administrative regions (33 and 28 were identified as orphan respectively by the SITVIT2 and mbovis.org databases), with the most dominant spoligotype being SIT1037/ SB0944 (77/203, 37.93%). Analysis of the bovine and human M. bovis isolates showed 75% (3/4) human M. bovis isolates sharing the same spoligotype pattern with the bovine isolates. Conclusion: Our study identified that approximately 29% of M. bovis strains causing BTB in Northern Ghana are caused by uncharacterized spoligotypes. Our findings suggest possible zoonotic transmission and highlight the need for BTB disease control in Northern Ghana. Author summary: Bovine tuberculosis (BTB) is a disease of global public and animal health significance. The disease is endemic in major livestock producing countries in sub-Saharan Africa. Little or no attention is given to the disease and its impact on livestock and humans. We conducted a cross sectional molecular epidemiology study in Northern Ghana to understand the population structure and distribution of tuberculosis in cattle and to assess the possibility of transmission of the disease to humans. We collected tuberculosis-like lesions from selected cattle organs from three regional abattoirs in the five administrative regions of Northern Ghana and found half of the total samples to be infected with Mycobacterium bovis. Majority of our isolates appeared to be uncharacterised suggesting the need for routine tracking and characterisation of the M. bovis species circulating in the sub-region. Comparison of our analysis of the M. bovis from bovine origin to that obtained from human M. bovis from the same geographical area showed 75% (3/4) of the human M. bovis isolates having same molecular pattern with the bovine isolates. Our findings suggest possible zoonotic transmission and highlight the need for BTB disease control in Northern Ghana. [ABSTRACT FROM AUTHOR]