Introduction
Mycobacterium tuberculosis, known to be responsible for most tuberculosis (TB) infections in humans, is inadvertently considered to be the only cause of the disease in humans in Nigeria.
Consequently, very little is known in the country about zoonotic TB caused by M. bovis, and other members of the M. tuberculosis complex (MTC) including M. africanum, M. caprae, M. bovis BCG, M. canetti, M. microti, and M. pinnipedii. Though human TB and bovine TB (BTB) are highly prevalent, respectively, in the human and cattle populations in Africa (including Nigeria), limited actions, particularly as they relate to BTB, are taken to reduce the prevalence of these dangerous diseases (Ayele et al. 2004).With over 170 million people, Nigeria has the largest human population in Africa, making it the most populous black nation in the world (WHO 2015). Additionally, Nigeria has a rapidly growing livestock population, estimated at 20.5 million cattle,
23.1 million sheep, and 28.1 million goats (FAO 2014). Despite this huge livestock resource, Nigeria has a large proportion of the world’s poor livestock keepers, making it a potential hotspot of neglected zoonoses, and a reservoir of endemic tropical diseases.
Nigeria remains one of the countries with the highest human TB burdens in the world, and it is currently ranked 4th globally, and 1st in Africa (WHO 2015). To reverse this situation, the Federal Government of Nigeria has been collaborating with the World Health Organization (WHO) and other international donors (e.g. Global Fund) over the past decade to improve the infrastructure to control TB (an initiative that is currently directed exclusively at controlling human TB) by increasing the number of directly-observed-treatment-short-course (DOTS) centers in the 774 local government areas (LGAs) in Nigeria. Very little consideration is, however, still
S.
I. B. Cadmus (*)Tuberculosis and Brucellosis Research Laboratories, Department of Veterinary Public Health & Preventive Medicine, University of Ibadan, Ibadan, Nigeria
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A. B. Dibaba et al. (eds.), Tuberculosis in Animals: An African Perspective, https://doi.org/10.1007/978-3-030-18690-6_17 given to the fact that most Nigerians live in settings that facilitate the transmission of zoonotic BTB at the human—animal interface. For example, in most rural areas, people live in close contact with their animals, and the current TB control initiatives do not make any provision for the protection of livestock handlers who are at a greater risk of exposure to zoonotic TB due to their unhygienic working conditions in livestock markets, and in urban and peri-urban abattoirs. Disruption of public health services, poor social amenities, lack of infrastructure such as piped water, and high levels of illiteracy, promote the persistence of poor hygienic conditions and low sanitation levels. These have led to the continuing spread of neglected tropical and other zoonotic diseases, including BTB in Nigeria. Other local risky practices that enhance the occurrence of zoonotic BTB infections in humans specifically occur when people drink unpasteurized milk and milk products, and consume meat and meat products contaminated with M. bovis (Cadmus et al. 2006).
Knowing that human and animal health are intricately linked in the Nigerian socio-economic setting and geographical space, it is imperative that we take a closer look at BTB in Nigeria. The objectives of this chapter are to review the burden and risk factors of BTB in Nigeria, and the challenges facing its diagnosis and control. The contribution of BTB to the overall human TB burden in Nigeria and factors contributing to the zoonotic transmission of M. bovis are also assessed. Finally, it is hoped that this information will assist governmental decision-makers to design a comprehensive strategy based on the One Health approach to reduce the impact of zoonotic BTB on Nigeria’s diverse human population.
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