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. 2022 Aug 3;16(8):e0009964.
doi: 10.1371/journal.pntd.0009964. eCollection 2022 Aug.

Prevalence of bovine tuberculosis and characterization of the members of the Mycobacterium tuberculosis complex from slaughtered cattle in Rwanda

Jean Bosco Ntivuguruzwa  1   2 , Anita L Michel  1 , Francis Babaman Kolo  1 , Ivan Emil Mwikarago  3 , Jean Claude Semuto Ngabonziza  4   5 , Henriette van Heerden  1
Affiliations

Prevalence of bovine tuberculosis and characterization of the members of the Mycobacterium tuberculosis complex from slaughtered cattle in Rwanda

Jean Bosco Ntivuguruzwa et al. PLoS Negl Trop Dis. .

Abstract

Background: Bovine tuberculosis (bTB) is an endemic disease in Rwanda, but little is known about its prevalence and causative mycobacterial species. The disease causes tremendous losses in livestock and wildlife and remains a significant threat to public health.

Materials and methods: A cross-sectional study employing a systematic random sampling of cattle (n = 300) with the collection of retropharyngeal lymph nodes and tonsils (n = 300) irrespective of granulomatous lesions was carried out in six abattoirs to investigate the prevalence and identify mycobacterial species using culture, acid-fast bacteria staining, polymerase chain reaction, and GeneXpert assay. Individual risk factors and the origin of samples were analysed for association with the prevalence.

Findings: Of the 300 sample pools, six were collected with visible TB-like lesions. Our findings demonstrated the presence of Mycobacterium tuberculosis complex (MTBC) in 1.7% (5/300) of sampled slaughtered cattle. Mycobacterium bovis was isolated from 1.3% (4/300) animals while one case was caused by a rifampicin-resistant (RR) M. tuberculosis. Non-tuberculous mycobacteria were identified in 12.0% (36/300) of the sampled cattle. There were no significant associations between the prevalence and abattoir category, age, sex, and breeds of slaughtered cattle.

Conclusions: This study is the first in Rwanda to isolate both M. bovis and RR M. tuberculosis in slaughtered cattle indicating that bTB is present in Rwanda with a low prevalence. The isolation of RR M. tuberculosis from cattle indicates possible zooanthroponotic transmission of M. tuberculosis and close human-cattle contact. To protect humans against occupational zoonotic diseases, it is essential to control bTB in cattle and raise the awareness among all occupational groups as well as reinforce biosafety at the farm level and in the abattoirs.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Map of Rwanda with provinces and districts and red stars show the locations of abattoirs visited in this study.
This map was produced in the ArcGis Desketop 10.1–10.8.2 of the University of Rwanda with concurrent use and Education licence. Spatial data (shapefiles) are freely available from DIVA-GIS. (https://gadm.org/download_country.html and https://diva-gis.org/gdata).
Fig 2
Fig 2. Agarose gel electrophoresis of the Mycobacterium tuberculosis complex differential PCR assay.
Lane M: GeneRuler 100 bp (Invitrogen, Thermo Fischer Scientific, South Africa), lanes 1–4: Non-tuberculosis mycobacteria (NTM) which amplified 1030 bp; lane 5: M. tuberculosis which amplified 1030 bp, 372 bp, 235 bp, 172 bp, and 146 bp; lanes 6–9: M. bovis which amplified 1030 bp, 372 bp, 146 bp, and 108 bp; lane 10: sterile ultrapure water used as negative control; lane 11: M. tuberculosis reference strain 2517.
See this image and copyright information in PMC

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