Epidemiology of Mycobacterium tuberculosis complex Infections in Cattle and Humans in the Remote Pastoral Settings of Southern Ethiopia

Temesgen Mohammed ¹ Fekadu Desta ² Biniam Wondale ³ Aboma Zewude ¹ Gezahegne Mamo Kassa ⁴ Hazim Khalifa ¹ Berecha Bayissa Demme ⁵ Gobena Ameni ^1,2*

• ¹ United Arab Emirates University, Al-Ain, United Arab Emirates
• ² Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Addis Ababa, Ethiopia
• ³ College of Social Sciences and Humanities, Arba Minch University, Arba Minch, Southern Nations, Nationalities, and Peoples' Region, Ethiopia
• ⁴ College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O. Box 34, Debre Zeit, Ethiopia., Addis Ababa, Ethiopia
• ⁵ National Laboratory for Veterinary Drug Residues, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China

Introduction: Mycobacterium tuberculosis complex (MTBC) infections are characterized by the development of granulomatous lesions in different parts of the bodies of animals and humans. MTBC infections causes significant economic and public health consequences in Ethiopia. However, there is a shortage of epidemiological data on the MTBC infections in the pastoral regions of the country. The objective of the present study was to investigate the epidemiology of MTBC infections in cattle and humans in the remote pastoral setting of southern Ethiopia.A cross-sectional study design was used to recruit 2396 cattle and 1200 TB presumptive human tuberculosis (TB) for this study from the southern pastoral districts of Ethiopia. Single intradermal comparative cervical tuberculin test (SICCTT) was used for screening bovine TB in cattle while mycobacterial culture and spoligotyping were used for the identification of mycobacterial species and strains in pastoralists.The herd and animal prevalences of bovine TB were 14.9% (95% confidence interval, CI = 10.2 -19.5%) and 3.2% (95% CI: 2.5 -4.0), respectively. Herd prevalence was associated with the district ( 2 = 40.10, p < 0.001). Based on multivariable binary logistic regression analysis, male animals were 1.77 (95% CI: 1.02 -3.05) times more likely to be TB positive than female animals. Similarly, cattle kept in Dasenech and Benetsemi districts were 10.65 (95% CI: 2.47-45.87) and 22.94 (95% CI: 5.48-95.94) times more likely to be TB positive than cattle kept in Selamago district, respectively. Mycobacterial culture positivity was 13.4% while spoligotyping identified Euro-American (EA), East-African-Indian (EAI), Indo-Oceanic (IO), lineage 7, M. bovis and M. africanum major lineages with proportions of 67.3% (105/156), 22.4% (35/156), 6.4% (10/156), 1.9% (3/156), 1.3% (2/156) and 0.6% (1/156), respectively.In general, the prevalence of bovine TB was relatively lower than those recorded in intensive dairy farms in central Ethiopia. Three species of MTBC namely, M. tuberculosis, M. africanum and M. bovis were isolated from pastoralists of southern Ethiopia. The isolation of M. bovis from pastoralist could suggest its zoonotic transmission from cattle to humans.