| dc.description.abstract | Mycobacteriosis is a chronic or acute systemic granulomatous disease that affects mammals, fish and birds. There are over 150 species recognized in Mycobacterium genus. The genus is divided into three groups according to clinical importance: obligatory human and animal pathogens, potentially pathogenic microorganisms (opportunistic) for animals and humans, and saprophytes or ubiquitous microorganisms. In cattle, mycobacteriosis is mainly caused by Mycobacterium bovis subsp.bovis. Recently Mycobacteria Other Than Tuberculosis (MOTTs) have been isolated from tubeculous lesions in cattle. This study was carried out to determine the prevalence, etiology, public health importance, and economic impact of bovine mycobacteriosis in Laikipia County, Kenya. A cross-sectional study was conducted at Laikipia Municipality Abattoir in Laikipia County between January and July, 2015. Post mortem meat inspection was carried out according to procedures established by legislation (Meat Control Act, cap.356), where samples suggestive of tuberculous lesions from inspected cattle carcasses were taken, trimmed and packed in sterile labelled Falcon tubes, transported to the laboratory and stored at -20 OC before processing. During processing in a level II laboratory, samples were homogenized and decontaminated. Smears were prepared and stained by the Ziehl-Neelsen method. The samples were then cultured in three different Loweisten-Jensen (L-J) media containing either pyruvate, glycerol or para-nitro benzoic acid. Cultures were incubated for 4-12 weeks. The isolates were then speciated by molecular analysis using PCR. GenoType Mycobacterium MTBC, CM and AS kits (Hains Lifescience, Germany) were used in this analysis. Economic impact of mycobacteriosis at the abattoir was determined by estimating the value of organs and tissues condemned due to presence of lesions. At national level, a desktop study was conducted to collect and collate the information on losses of export opportunities due to bovine tuberculosis threat in Kenya. Trade inquiries for the last ten (10) years were analysed and given monetary values.
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One thousand (1000) cattle carcasses were sampled for the study and the prevalence was found to be 21.8% (218/1000) on the basis of gross lesion. Direct ZN staining detected Acid Fast Bacilli (AFB) in 28.9% (63/218) of all the lesions. L-J media isolated 22.9% (50/218) isolates, which were further analyzed for mycobacteria species using PCR. Mycobacteria were identified in 70% (35/50) of the isolates. The isolated mycobacteria were Mycobacterium fortuitum at 24% (12/50), Mycobacterium bovis subsp. bovis 6.0% (3/50), Mycobacterium shimoidei 4.0% (2/50) and Mycobacterium asciaticum, Mycobacterium interjectuctum, Mycobacterium szulgai, Mycobacterium celatum, Mycobacterium kansaasii at 2.0% (1/50) each. Mycobacterium species could not be speciated in 26% (13/50) of the isolates and 30% (15/50) isolates were negative for mycobacteria. The overall prevalence of mycobacteriosis in this study was 3.5% (35/1000) [95% CI: 2.53-4.83]. Condemned organs and tissues weighed 422 kilograms which translated to an estimated loss of 168,800 Kenya shillings for the study period. Annual estimated loss was 506,400 Kenya shillings (USD 5,604). At the national level two enquiries failed for the 10 year period under consideration (2008 – 2014) with an estimated economic loss of Kenya shillings 474mln (4.74million USD). This study demonstrated the presence of Mycobacterium bovis subsp.bovis, Mycobacterium fortuitum, Mycobacterium shimoidei, Mycobacterium asciaticum, Mycobacterium interjectuctum, Mycobacterium szulgai, Mycobacterium celatum, Mycobacterium kansaasii, and Mycobacterium species as causative agents of mycobacteriosis in cattle in the study area. Further, MOTTS isolated from cattle in this study have been found by other researchers to cause pulmonary tuberculosis in humans. In conclusion, diagnosis of bovine tuberculosis should take into account the pathogenic potential of Mycobacteria Other Than Tuberculosis (MOTTs). Condemnation of organs/tissues and restriction on animal trade due to bovine mycobacteriosis impacts negatively on the national economy. | en_US |
