A Paradigm Shift: Urbanization and Intensification
With the exception, perhaps, of Namibia, Botswana, and South Africa, there are few countries in Africa with well-developed sophisticated dairy and meat industries that participate in the international trade.
In general, cattle farming on the continent utilizes the age-old traditional pastoral, extensive, or transhumant husbandry systems. These involve extensive seasonal movement, often over vast distances, within countries and across international borders, of people and animals in search of the limited sources of natural pasture and water.In traditional African livestock husbandry, livestock is deeply embedded in the social system, and stock ownership is a sign of wealth; the more cattle you have, the wealthier you are. The role of livestock in the agropastoral populations of tropical Africa is much more complex than in temperate climates (Alaku and Moruppa 1993; Coulibaly and Yameogo 2000). Cattle are seldom culled or sold, but are often exchanged, in a complex social system of mutual obligation, within and between families and other social groups. Also as part of this close association between humans and livestock in many parts of Africa, the stockowners share their houses with shoats, fowls, and often cattle. These practices, which lack the application of the most basic of hygienic precautions and biosecurity measures, set the stage for the rapid transmission of M. bovis when the disease is present in a herd (Carmichael 1938).
In Africa, between 40 and 45% of the population live in abject poverty, while a further 30% is classified as extremely poor. There is a rapid population growth of 3% per annum, and urbanization is increasing at a rate of 6% per annum and is a driver of the increasing poverty and lack of food security across the continent. These are major causes of concern particularly in sub-Saharan Africa (SSA) (Unger and Munstermann 2004), and people in urban areas here attempt to improve their livelihoods by diversifying their income, and a significant number of them are entering the livestock sector and, in particular, small-scale dairy farming within and around the cities (Awah-Ndukum et al.
2010). As a result, in all parts of Africa, an increase in milk production is observed around major towns and cities to satisfy the needs of the increasing urban populations. These farmers are often organized into designated milk-shed areas or into smallholder cooperatives, also known as bulking groups (Tschopp et al. 2013). Authorities in Africa support these initiatives (Asseged et al. 2000; Tschopp et al. 2013), particularly in peri-urban centers where the demand for dairy products is very high, because some of their major challenges are to ensure a year-round supply of sufficient infrastructure for processing, preservation, and marketing of the products (meat and milk) and animal feed (Unger and Munstermann 2004). To improve productivity in the sector, there is, in addition, an increasing effort to introduce improved dairy breeds and to change the extensive rural farming practices to intensive management systems.These changes are not without their challenges. Intensification of livestock production, particularly where regulations governing animal movement and importation are nonexistent or poorly enforced, often results in an increase in the incidence of BTB (Benkirane 1998; Boukary et al. 2012), and it has, in fact, become a serious problem in intensive dairy farms, impacting the productivity of the livestock industry in many of the developing countries. As an example, a recent study carried out on intensive dairy farms in and around Addis Ababa, Ethiopia, showed an overall prevalence of BTB of 10.3% and a prevalence of up to 90% in market-orientated farms that keep large numbers of improved HolsteinZFriesians and their crosses (Asseged et al. 2000). This situation can destroy years of genetic improvement of desirable production traits in a herd (Skuce et al. 2012). Bovine TB also negatively impacts the welfare of affected farming communities due to its effect on profitability and trade and the inability to participate in the lucrative international trade in meat and dairy products.
An additional, and critical, problem is that veterinary services, including access to diagnostic laboratories, in most of the nations are inadequate. They also fail to regulate animal movement because of the lack of systematic and verifiable animal identification systems (Amanfu 2006). This situation also does not allow them to trace the sources of BTB-positive cattle identified by skin testing or by meat inspection at abattoirs, and they have limited opportunity to control the disease under these circumstances.
There is a strong link between poor human health and poverty and their likelihood of contracting zoonotic diseases (Unger and Munstermann 2004). Under these circumstances, farmers, abattoir workers, butchers, and veterinarians are at a high risk of acquiring the infection. Because of traditional ethnic practices in certain countries in Africa, humans and animals share the same microenvironment, and under these circumstances, cases of zoonotic M. bovis infection in humans are common (Cosivi et al. 1998). As would be expected, this occurs particularly in peri-urban, unsanitary, livestock production centers that increase the risk of contracting zoonotic diseases. Transhumant communities in rural areas in certain countries are, unexpectedly, also exposed and subject to contracting zoonoses because of their close association with their livestock.
In countries where BTB is common, M. bovis infection is estimated to be responsible for 10%-15% of human TB cases (Ashford et al. 2001). Large sectors of the African population drink unpasteurized milk that is a common source of the infection, and it is only in urban areas that there is an increasing supply of processed pasteurized milk. There is a perception that the souring of milk, a common practice throughout Africa because of lactose intolerance, kills mycobacteria and renders the milk safe to drink, but the microbicidal effect of souring is dependent on the stage of the souring process, since viable M. bovis organisms still occur in the milk during the early stages of the process (Michel et al. 2015).
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