A Cross-sectional Study on Zoonotic and Reverse Zoonotic Transmission of Tuberculosis in Central Ethiopia

Abstract Background: The zoonotic transmission of tuberculosis (TB) from cattle to humans has long been recognized while its reverse zoonotic transmission from humans to animals has recently been reported. The socioeconomic situations of the rural communities of Ethiopia are conducive for the zoonotic and reverse zoonotic transmission of TB between cattle and human. The objective of this study was to investigate the zoonotic and reverse zoonotic transmission TB between humans and cattle central Ethiopia.Methods: To achieve this objective a cross-sectional study was conducted on 1896 cattle slaughtered in two abattoirs and 392 TB suspicious human subjects visiting health institutions for treatment. Post mortem examination, mycobacteriological culture, and spoligotyping were used for the study. In addition, the Spoligotype International Types and VNTR (variable number of DNA tandem repeats) International Types (SITVIT2) database and the online “Run TB-Lineage” were used to identify SIT and lineages of the human and cattle isolates.Results: Gross TB lesion was detected in 4.2% (80/1896) the slaughtered cattle and predominantly (52.5%) found in the thoracic cavity. But culture positivity was only 26.3% (21/80) in suspicious lesions. Of the 21 cattle isolates, 12 (57.2%) were M. bovis while the remaining nine (42.8%) were M. tuberculosis. SIT50, SIT118 and SIT1318 were isolated from both humans and cattle. Similar to the low culture yield in cattle tissues, only 22% (86/392) the sputa from TB suspicious humans were culture positive. These 86 human isolates were classified into 81 M. tuberculosis, three M. africanum and two M. bovis by spoligotyping. The two human M. bovis isolates had the pattern of SB1443, which was not isolated from cattle in this study.Conclusion: The zoonotic and reverse zoonotic transmissions of TB were confirmed in Ethiopia by the isolation of two M. bovis from human and isolation of nine M. tuberculosis from cattle, which suggested higher role of M. tuberculosis in cattle compared to the role of M. bovis in humans.