Zoonotic BTB: Global Realities and Facts from the World Health Organization
The World Health Organization (WHO), in conjunction with the Food and Agriculture Organization (FAO) of the United Nations, previously recommended that the epidemiological data pertaining to human TB caused by M.
bovis infections, particularly in populations at risk (e.g., livestock workers, veterinarians, hunters, and zoo workers) (WHO-FAO 1994), be collected. The African countries, unfortunately, did not respond to this request, and the information about the disease on the continent remains piecemeal and anecdotal (AU-IBAR 2013). Based on the available raw and incomplete data, Muller et al. (2013) estimated that in Africa there would be 7 zTB cases/100,000 population/year, caused by infection with M. bovis, which is approximately 1% of the total human TB burden. More recently, in 2015, the WHO estimated that 149,000 cases of M. bovis zTB with a mortality of 13,400 occurred globally (WHO 2015a) and that of these 76,300 cases and 10,000 deaths were expected to occur in Africa (WHO 2016a). They considered these figures to be an underestimation given the absence of routine reporting of the disease in most countries in Africa in which BTB is endemic.The degree of under-investigation, and the likely underestimation of the number of zTB cases in Africa and in some of the other developing countries, implies that the actual number of human zoonotic BTB cases remains unknown but that it may be substantially more than the current estimate (Perez-Lago et al. 2014). With the persistence of M. bovis in cattle in most African countries (Cadmus et al. 2006; Perez-Guerrero et al. 2008; Oloya et al. 2008; Jenkins et al. 2011; Egbe et al. 2016) in association with the general poor standards of living and hygiene, there is a risk that zoonotic BTB will not remain an African problem but that it may become a global health threat (see also Chap. 3).
The increasing emphasis on addressing these issues is largely due to the attention that zTB received globally in recent times in a number of scientific meetings, workshops, symposia, and technical sessions on TB (WHO 2015b, c; IUATLD
2015). The WHO in 2016 (WHO 2016a) informed that:
... accelerating the annual decline in TB incidence, reaching the 2020 milestone of a 35% reduction in TB deaths, requires reducing the global number of people with TB who will die from the disease (the case fatality ratio, or CFR) from 17% in 2015 to 10% by 2020.
The WHO’s End TB Strategy (where every case of TB counts, no matter what its source) accepted by the World Health Assembly in 2014 (WHO 2015b) and the Global Plan to End TB in 2016-2020 (Stop TB Partnership 2015) further emphasize the need to address these deficiencies and to include the issue of zoonotic tuberculosis in planning the eventual eradication of TB. More importantly, the End TB objective was adopted as part of the global Sustainable Development Goals (UN 2015). Therefore, within this context, there were calls for better diagnosis and treatment of every human TB case, including those with zTB.
Apart from the aforementioned, the lack of global concern about zTB remains a problem, given that human TB is generally, and specifically in some African countries, considered to be caused only by M. tuberculosis, without taking into account the role played by other members of the MTC, particularly M. bovis. Consequently, the general consensus was that current global initiatives to control and eradicate TB must involve a more holistic approach. This is based on the knowledge that a critical mass of the world population lives in neglected communities where cohabitation with animals (particularly cattle) is common. Thus, as a way forward, a pragmatic approach to end TB must incorporate an all-inclusive strategy that will simultaneously focus on the disease in both humans and animals. Toward this end, a meeting of a committee of experts from academia, WHO, the World Organization for Animal Health (OIE), the FAO, International Union Against Tuberculosis and Lung Disease (IUATLD), and relevant research institutions was held at the WHO headquarters, Geneva, Switzerland, in April 2016 to deliberate on key priorities needed to reduce the burden of zTB.
This culminated in the acceptance of zTB as a priority of the WHO at its Strategic Technical Advisory Group for TB (STAG-TB) meeting in June 2016 (Green 2006; WHO 2016b).Because of the uncertainty about the actual number of zoonotic TB cases, the future prevention and control of M. bovis infections require the improvement of, and the use of rapid and accurate diagnostic tools, more comprehensive surveillance programs and greater collaboration between veterinary and medical health officials (Perez-Lago et al. 2014; WHO 2016b). These challenges provide an opportunity to reflect on the need for applying the principles of One Health to the control and eventual eradication of BTB and zTB.
4.4