Spoligotype analysis of Mycobacterium bovis isolates from cattle and assessment of zoonotic TB transmission among individuals working in bovine TB‐infected dairy farms in Ethiopia

Abstract

Bovine tuberculosis (bTB) is a disease with impact on dairy productivity, as well as having the potential for zoonotic transmission. Understanding the genetic diversity of the disease agent Mycobacterium bovis is important for identifying its routes of transmission. Here we investigated the level of genetic diversity of M. bovis isolates and assessed the zoonotic potential in risk groups of people working in bTB‐infected dairy farms in central Ethiopia. M. bovis was isolated and spoligotyped from tissue lesions collected from slaughtered cattle as well as from raw milk collected from bTB positive cows in dairy farms from six urban areas of central Ethiopia. From consented dairy farm workers, knowledge and practices related to zoonotic TB transmission, together with demographic and clinical information, was collected through interviews. Sputum or Fine Needle Aspirate (FNA) samples were collected from suspected TB cases. Spoligotyping of 55 M. bovis isolates that originated either from cattle tissues with tuberculous lesion or from raw milk revealed seven spoligotype patterns where SB1176 was the most prevalent type (47.3%). Most isolates (89.1%) were of the M. bovis African 2 clonal complex. All sputum and FNA samples from 41 dairy farm workers with symptoms of TB were culture negative for any mycobacteria. Among the 41 TB suspected farm workers, 61% did not know about bTB in cattle and its zoonotic potential, and over two‐third of these workers practiced raw milk consumption. Our spoligotype analysis suggests a wider transmission of a single spoligotype in the study area. The results reported here may be useful in guiding future work to identify the source and direction of bTB transmission and hence design of a control strategy. Isolation of M. bovis from milk, knowledge gap on zoonotic TB and practice of consumption of raw milk in the study population showed potential risk for zoonotic transmission.

Systematic Review of Knowledge, Attitudes, and Practices of Dairy Farmers and Consumers Towards Bovine Tuberculosis in Low- and Middle-Income Countries

“…Few studies investigated whether farmers knew that raw milk and dairy (Africa n=8; Asia n=2) or raw meat (Africa n=6) consumption could result in zoonotic infection with bTB (28, 30, 31, 33, 44, 62). Except for the farmer populations investigated by Kazoora et al (44), most studies found this knowledge was prevalent among less than 30% of the farmers interviewed.…”

Recent progress in the genotyping of bovine tuberculosis and its rapid diagnosis via nanoparticle-based electrochemical biosensors

“…Knowledge of the genetic diversity of M. bovis is necessary for detecting its routes of transmission. 135 Single nucleotide polymorphism (SNP) analysis within virulence genes, which appear with the highest number of SNPs, indicated that M. bovis was continuously modifying and adapting specific mechanisms to sustain dissemination among environments and different hosts. 136 The identification of non-synonymous SNPs on the virulence genes allowed for the differentiation of various groups.…”