Zoonotic transmission of tuberculosis between pastoralists and their livestock in South-East Ethiopia.

Balako Gumi,Wondale Mekonnen,Elena Hailu,Esther Schelling,Abraham Aseffa,Rebuma Firdessa,Girume Erenso,Jemal Hussein,Ermias Melese,Stefan Berg,Jakob Zinsstag

doi:10.1007/s10393-012-0754-x

Abstract

Despite huge global efforts in tuberculosis (TB) control, pastoral areas remain under-investigated. During two years sputum and fine needle aspirate (FNA) specimens were collected from 260 Ethiopian pastoralists of Oromia and Somali Regional States with suspected pulmonary TB and from 32 cases with suspected TB lymphadenitis. In parallel, 207 suspected tuberculous lesions were collected from cattle, camels and goats at abattoirs. All specimens were processed and cultured for mycobacteria; samples with acid-fast stained bacilli (AFB) were further characterized by molecular methods including genus and deletion typing as well as spoligotyping. Non-tuberculous mycobacteria (NTM) were sequenced at the 16S rDNA locus. Culturing of AFB from human sputum and FNA samples gave a yield of 174 (67%) and 9 (28%) isolates, respectively. Molecular typing was performed on 173 of these isolates and 160 were confirmed as Mycobacterium tuberculosis, three as M. bovis, and the remaining 10 were typed as NTMs. Similarly, 48 AFB isolates (23%) yielded from tuberculous lesions of livestock, of which 39 were molecular typed, including 24 M. bovis and 4 NTMs from cattle, 1 M. tuberculosis and 1 NTM from camels and 9 NTMs from goats. Isolation of M. bovis from humans and M. tuberculosis from livestock suggests transmission between livestock and humans in the pastoral areas of South-East Ethiopia

Highlights

Ethiopia ranks seventh among the world’s 22 countries with high tuberculosis (TB) disease burden and had an estimated incidence rate of 379 cases per 100,000 people per year (WHO 2008)
Cattle are considered to be the main hosts of M. bovis, isolations have been made from many other livestock and wildlife species and transmission to humans constitutes a public health problem (Ayele et al 2004; OIE 2009)
The objectives of this study were first to assess the presence of M. bovis among human TB patients and to describe mycobacterial strains circulating in South-East Ethiopian pastoralists and their livestock using a ‘‘One health’’ approach, studying human and livestock hosts simultaneously (Zinsstag et al 2009)

Summary

Introduction

Ethiopia ranks seventh among the world’s 22 countries with high tuberculosis (TB) disease burden and had an estimated incidence rate of 379 cases per 100,000 people per year (WHO 2008). Cattle are considered to be the main hosts of M. bovis, isolations have been made from many other livestock and wildlife species and transmission to humans constitutes a public health problem (Ayele et al 2004; OIE 2009). BTB has been reported from 33 of 43 African countries (Ayele et al 2004). Human cases of bTB have been described in Ghana, Niger, Uganda and Tanzania (Idigbe et al 1986; Addo et al 2007; Oloya et al 2008) and in immigrants from Chad (Godreuil et al 2010)

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