Genetic Diversity of Mycobacterium bovis Strains in Tanzania

There is a relatively extensive genetic polymorphism of M. bovis isolates in the different geographical regions in Tanzania, and the various strains are not uniformly distributed throughout the country (Mwakapuja et al.

Strain diversity is a characteristic of the isolates from across the country. Katale et al. (2013) and Mwakapuja et al. (2013a, b) reported a set of M. bovis strains, some of which were novel strains, in indigenous cattle. Another set of 13 different pTBN12 RFLP and 13 different spoligotypes isolated from animals and humans

Table 21.1 Risk factors associated with BTB in Tanzanian cattle herds (Katale etal. 2013; Shirima et al. 2003; Kazwala et al. 2001)

also confirmed the high degree of relatedness (86%) between the dominant pTBN12 genotypes (Kazwala et al. 2006).

The diversity of M. bovis spoligotypes in Tanzania requires further epidemiolog­ical studies given the detection of novel strains such as SB2289 and SB2290 (Katale et al. 2015) and SB2190 (de Garine-Wichatitsky et al. 2013) in indigenous cattle (Table 21.2). Some of these isolates from (SB2290) differed from those found in wild animals by the loss of a single spacer, suggesting that BTB infections in wild animals and cattle are epidemiologically linked (Katale et al. 2015). The genetic relatedness of M. bovis isolates from indigenous cattle and wild animals further suggests the existence of either evolutionary spillback of M. bovis infection from wild animal reservoirs to livestock or micro-evolutionary events of M. bovis in the cattle populations in the ecosystem, although some of them may have been

Table 21.2 Mycobacterium bovis strains (spoligotypes) isolated from cattle, other animals, and humans in Tanzania

introduced from elsewhere into the cattle and wildlife populations (Katale et al.

2015). In the Mikumi-Selous ecosystem, M. bovis was isolated only from indigenous cattle, highlighting the importance of pastoral livestock as a reservoir for M. bovis in systems in which both livestock and wildlife occur.

21.4