Abstract
Mycobacterium tuberculosis complex (MTBC) comprises closely related species responsible for human and animal tuberculosis (TB). Efficient species determination is useful for epidemiological purposes, especially for the elucidation of the zoonotic contribution. In Algeria, data on MTBC genotypes are largely unknown. In this study, we aimed to investigate the occurrence and diversity of MTBC genotypes causing human and bovine TB in Northern Algeria. During a two-year sampling period (2017–2019) in two regions of Northern Algeria, we observed an overall prevalence of 6.5% of tuberculosis (TB) among slaughtered cattle, which is higher than previous Algerian data yet comparable to neighboring countries. A total of 296 Mycobacterium tuberculosis complex (MTBC) isolates were genotyped by spoligotyping: 181 from tissues with TB-like lesions collected from 181 cattle carcasses and 115 from TB patients. In human isolates, we identified 107 M. tuberculosis, seven M. bovis and one “M. pinnipedii-like”, while for bovine samples, 174 isolates were identified as M. bovis, three as M. caprae, three as “M. pinnipedii-like” and one as “M. microti-like”. The majority of isolates (89.2%) belonged to 72 different known Shared International Types (SIT) or M. bovis spoligotypes (SB), while we also identified seven new SB profiles (SB2695 to SB2701). Twenty-eight of the SB profiles were new to Algeria. Our data suggest zoonotic transmission in Sétif, where significantly more TB was observed among cattle (20%) compared to the slaughterhouses from the three other regions (5.4%–7.3%) (p < 0.0001), with the isolation of the same M. bovis genotypes from TB patients. The present study showed a high genetic diversity of MTBC isolated from human and cattle in Northern Algeria. Even though relatively small in terms of numbers, our data suggest the zoonotic transmission of TB from cattle to humans, suggesting the need for stronger eradication strategies for bovine TB.
Highlights
Among infectious diseases, tuberculosis (TB) is one of the most significant in terms of public and animal health because of its high morbidity and mortality rate in humans, in addition to the economic losses related to affected herds [1,2]
The infection is caused by bacilli of the Mycobacterium tuberculosis complex (MTBC) [3], which includes 11 species: M. tuberculosis, M. bovis, M. africanum, M. microti, M. canettii, M. caprae, M. pinnipedii, M. suricattae, M. mungi, M. orygis and the dassie bacillus
Post-mortem inspection showed an overall prevalence of carcasses with TB-like lesions of 6.5% (232/3,546), with inter-region variability representing 5.4% (35/650) of cattle in Kherrata, 6.1% (150/2,460) in Bejaia and 7.3% (23/316) in El-Eulma abattoirs, which is significantly less compared to the 20% (24/120) in Setif (p < 0.0001; Table 1)
Summary
Tuberculosis (TB) is one of the most significant in terms of public and animal health because of its high morbidity and mortality rate in humans, in addition to the economic losses related to affected herds [1,2]. M. tuberculosis is the most prevalent causative agent of human pulmonary TB [4], infecting more than one-quarter of the world’s human population [5]. According to the World Health Organization (WHO), more than 10 million human TB cases were reported in 2018. The largest incidence rate of human TB occurred in the South-East Asian region, followed by the African region and the Western Pacific, with 44%, 24% and 18% of new cases, respectively [8]
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