Prevalence and Epidemiology of BTB in Rwanda

Bovine TB in Rwanda is listed as an endemic disease but without data estimates Cosivi et al. (1998). Contrary to the situation in human medicine where the diagnosis of TB is mainly based on microscopy, bacteriology, and molecular biological techniques, the diagnosis of BTB in Rwanda, like in many other developing coun­tries, is reliant on meat inspection, both for diagnosing and generating disease surveillance data.

An abattoir-based study conducted in 2009 at SABAN Nyabugogo Abattoir in Kigali, the capital city, revealed a prevalence of lesions consistent with those of BTB of 0.9% (n = 16,753). Mycobacterium bovis was confirmed to be present in about 60% of these cases (Habarugira et al. 2014). Additional data collected from the same abattoir indicated that the prevalence of BTB-like lesions fluctuates over time: in 2010, the occurrence of BTB lesions was 0.7%, it was slightly more than double in the following year (1.7%), and then varied between 0.5 and 1.5% in 2012 and 2013, respectively.

Although the prevalence of BTB in Rwanda appears to be low, it must be kept in mind that these data are based on the detection of macroscopic lesions during post-mortem examination of carcasses at abattoirs where commonly more than 50% of the BTB cases are missed during routine inspection (Teklu et al. 2004; Shitaye et al. 2006; Awah Ndukum et al. 2010; Biffa et al. 2010; Bekele and Belay 2011).

Bovine TB is an endemic disease in some neighboring countries such as Uganda and Tanzania (Ayele et al. 2004). Given the higher prevalence of BTB in Tanzania where it varies from 0.2 to 13.3% (Katale et al. 2012; Kazwala et al. 2001; Shirima et al. 2003), and in the western parts of Uganda that directly border on Rwanda and where the prevalence is up to 14.5% (Kazoora et al. 2014), it is likely that BTB could have a higher prevalence in Rwanda bordering those areas. Movement of BTB-infected cattle from these areas into Rwanda is highly likely considering the extent of animal trade between the countries, and particularly, the ongoing illegal movement of livestock across these international borders (Fig. 18.1).

As with other infectious diseases (Chatikobo et al. 2009; Juvenal and Edward 2010), it is possible that BTB is also prevalent in some of the wildlife species in the country. It is highly likely that it occurs in some of the wildlife species in the Akagera National Park in the Eastern Province of Rwanda where neighboring farmers graze their animals illegally in the Park allowing intermingling of livestock and wildlife that increases the likelihood of transmission of disease between them.

18.3