A Brief Overview of the Important Aspects

The chapters in this book deal with specific aspects of the disease caused by M. bovis in humans, livestock, and wildlife with the focus on Africa and the challenges associated with the detection, epidemiology, control, and eventual erad­ication of the disease from the continent.

The second chapter provides a broad overview of the status of the disease and its control in Africa. Bovine TB (BTB) is globally a notifiable disease and is classified by the World Animal Health Organization (the OIE) as being of socioeconomic and of public health importance. It is now also classified as one of the important neglected zoonoses. Against this background and the known presence of the disease in humans and animals in Africa since antiquity, little is known about its current status even though the first diagnosis of BTB in livestock was made in South Africa in 1880 and in wildlife during the course of the 1920s, and it is now known to occur throughout the continent.

For long, it has been assumed that the European settlers introduced BTB into Africa during the time of colonization, but it subsequently transpired that there are a number of indigenous strains, the Af clonal complexes of M. bovis, causing BTB in Africa. Control of the disease is complicated by its characteristically slow, insidious spread in cattle herds and populations, the lack of specific clinical signs, and the difficulty of eradicating the disease from livestock even in the developed countries in the world.

The complexity of the epidemiology of BTB is a major reason for the difficulties experienced in controlling it. Bovine TB is a multihost disease that also occurs in wildlife, some of which are maintenance hosts. Given the experience in some of the developed countries, such as the UK, New Zealand, and the USA, it appears to be impossible to eradicate the infection once one of the wildlife species in the same ecosystem becomes a maintenance host of the infection. Initially, BTB was consid­ered to be a disease of intensively farmed cattle housed during winter, and that it would not be a problem in extensively farmed cattle. This still appears to be the situation in Africa where there remains a perception, shown since to be false, that local breeds were less susceptible to the infection, and that the extensive manage­ment systems practiced in many parts of the continent, will limit the extent of the disease, and thus its importance. Based on these assumptions, the lack of information about the distribution and extent of the infection in African livestock and wildlife, and the limited financial and human resources, policy makers and veterinary author­ities mainly focus on the control of what they consider to be a more serious threat, the acute epidemic and endemic infectious diseases.

The marked increase in the size of the human population on the African continent and the rapid rate of urbanization are causing an increasing change in animal husbandry practices. To augment their income and to satisfy the burgeoning demand for milk of the expanding urban populations, there is now a trend to establish small­scale dairy farming in urban and periurban areas, and these practices result in a marked increase in the prevalence of BTB in many of those herds.

Internationally, the control of BTB is increasingly complicated by the presence and persistence of the disease in free-ranging wildlife and its bidirectional spread at the wildlife-livestock interface. It is anticipated that Africa, with its rich diversity of wildlife species, will also be plagued by this problem. Examples of maintenance hosts that have already been identified in Africa include African (Cape) buffaloes (Syncerus caffer), greater kudus (Tragelaphus strepsiceros), and Kafue lechwe (Kobus leche kafuensis), and there may be others. The role of these maintenance hosts is largely poorly researched, and they may in future prove to be a major obstacle in controlling and eradicating BTB from Africa.

The most pressing problems in dealing with the issues are the lack of application, and the absence of statutory control policies including surveillance for the presence of BTB in most of the African countries. These events result in a lack of information required to develop sound control policies and programs. In most African countries, there is a total lack of information about the presence of the disease, its impact on the livestock sector, and its role in humans as a serious, but neglected, zoonosis.

It is critical for African countries to address the challenges and dangers of the presence of the disease, given the rapid expansion in the numbers of humans and animals on the continent that will enhance the impact of the disease, and if it remains uncontrolled, it may reach catastrophic proportions. Additionally, the presence of uncontrolled BTB across the continent will inevitably have a major negative impact on the international drive to eradicate TB in humans within the next few decades, irrespective of the specific cause and the presence of zoonotic TB.

Chapter 3, dealing in more detail with zoonotic TB caused by M. bovis, also emphasizes the lack of information about the prevalence of the disease in humans in Africa, primarily because of the lack of sufficient laboratory infrastructure and funding to distinguish between M. tuberculosis and M. bovis isolates. Humans contract the disease in different ways: by drinking unpasteurized milk, by inhaling infected droplets when in close contact with infected animals shedding mycobacteria, and by eating meat contaminated with M. bovis. The prevalence of zoonotic TB in Africa is unknown but it is known to be higher in countries in which the prevalence of the disease in cattle is high and in countries where BTB is common, and in which 10-15% of humans may suffer from zoonotic TB.

There is a general attitude, based on the universal lack of information about zoonotic TB and anecdotal evidence, that zoonotic TB in Africa is not a problem, and thus does not merit monitory expenditure to create the necessary diagnostic infrastructure. As a result, the role that it may play in the epidemic occurrence of TB in humans in Africa is largely ignored. This is against the background of the extent to which it occurred in some of the European countries before BTB was controlled in cattle and milk was pasteurized, where 50% of TB cases in children with lymphad­enitis, and 65% of intestinal TB cases, were due to an M. bovis infection. Zoonotic TB is the main reason for introducing pasteurization of milk and for justifying the massive financial expenditure over many decades by developed countries to control BTB in their national cattle herds. Large sections of the African population do not have access to pasteurized milk and prefer to drink raw milk, or partially fermented milk. Ethnic practices also cause people to eat high-risk meat and meat products, and contrary to common belief, certain sectors of the nomadic people live in close association with their animals, thus enhancing the likelihood of contracting the disease caused by M.

The likelihood that HIV-AIDS may enhance human infection with M. bovis in Africa has been raised as an additional reason why more attention should be given to this infection, but it appears, according to the limited available information, that this is not the case. One further important complication of not identifying M. bovis in human TB cases is the likelihood of the development of drug-resistant M. bovis strains as it is already resistant to rifampicin, one of the front-line drugs used for treatment of TB in humans. In this context, XDR M. bovis strains have been identified, and if they are to extend into Africa, their presence may develop into a health threat that would be most difficult to deal with.

The current Iiaisesfaire approach by policy makers and the human and veterinary regulatory authorities may yet prove to be a risky one, given the general lack of information about the disease. The occurrence of hotspots of M. bovis infection has been reported in Tanzania where, in areas, the prevalence of zoonotic TB in humans reached 10-38%. There may be many more such hotspots, and with the expected increase in the human population and urbanization, the general lack of control of the disease in cattle and the ignorance of farmers and consumers about the disease, zoonotic TB may have disastrous effects in times to come. As an example, an average herd prevalence of 10.5% and an in-herd BTB prevalence of up to 90% have been reported in intensive dairy farms in Ethiopia, and it is only reasonable to expect that this would eventually also be reflected in the number of zoonotic TB cases in those areas.

Chapter 4 deals with the control of the disease by applying the multidisciplinary approaches of One Health to facilitate the control and eradication of human TB, thus implying also the control and eradication of BTB. The complexity of BTB, because of the involvement of multiple susceptible species including humans, and the presence of wildlife maintenance hosts, makes it imperative that a broad multidisciplinary approach be adopted to engender some hope of success with the attempted control and eradication of both BTB and zoonotic TB in Africa.

Although it has been known since the 1920s that various African wildlife species may contract BTB, for many years little attention has been given to the disease in wildlife in Africa. The occurrence of BTB in African wildlife and its impact on the epidemiology of the disease is dealt with in Chap. 5. Currently, at least, 29 different free-ranging wildlife species have been diagnosed with BTB. Few of them, such as African buffaloes, greater kudus, warthogs, and Kafue lechwe are maintenance hosts, sustaining the infection and transmitting the disease to cattle and other species at the interface. Most of the others are spillover hosts that may, or may not, play a role in transmitting the disease to other wildlife, livestock, and humans.

Globally, the role of wildlife as maintenance hosts of M. bovis infections, and their role in the epidemiology of the disease increasingly became apparent during the last few decades. This situation creates a major challenge for Africa against the background of the diversity of its wildlife and the extensive intermingling at the interface between wildlife, livestock, and humans in many parts of the continent. Bovine TB in wildlife may also impact negatively on the species infected, particu­larly those that are endangered and close to extinction, on conservation efforts, and on the income generated by the lucrative wildlife ranching enterprises in Southern Africa. Fundamentally, the only way in which the infection in wildlife could eventually be controlled would be by vaccination, but no effective vaccine has yet been developed. For African countries that want to attempt to control and eradicate BTB, the extent of the infection and the epidemiology of the disease in wildlife will have to be determined, to allow the development of effective control programs that will have the potential to guide activities to eradicate the disease.

Wildlife, livestock, and humans are also infected by other species of the Myco­bacterium tuberculosis complex (MTC) that evolved between 40,000 and 70,000 years ago from a common ancestral human pathogen of African origin. Many of these mycobacteria are host-specific but others cross species barriers. Some of the mycobacterial species are primarily found in Europe and Asia, but others, the African sublineage of the RD9-deleted clade, occur mostly in Africa. Mycobacte­rium africanum, a common cause of TB in humans in Western Africa, is rarely isolated from domesticated animals. The details of other wildlife-related species, including the chimpanzee bacillus, the dassie bacillus, M. mungi, M. surricattae, and M. orygis, are dealt with in Chap. 6. These organisms appear to be particularly host-specific and transmission to humans and livestock seems to be unlikely. However, being able to identify these mycobacteria may be important in the understanding of the epidemiology of TB in humans and animals, and the conse­quences of these infections for free-living wildlife and domesticated species. It is important, though, to keep in mind that the growth characteristics of these bacteria are poorly defined, that they are usually slow growers, and that they are difficult to culture. In addition, the genetic markers used to define lineages of the MTC may be ambiguous, and may result in the misclassification of some of the species in the MTC.

To adequately design control strategies for BTB, knowledge of its epidemiology that varies from country to country and even within countries is important. The data available for Africa are largely incomplete, fragmented, historical, often contradic­tory, and difficult to process. That which is known is collated in Chaps. 7 and 8, respectively, presenting the data based on the Epidemiologic Problem Oriented Approach (EPOA) and its molecular epidemiology. The lack of formal control measures for BTB, prevailing animal husbandry practices such as transhumance (leading to the uncontrolled movement of cattle and other livestock within and between countries), increasing urbanization and burgeoning smallholder dairy farm­ing in urban and periurban areas, and the presence of the infection in a large number of wildlife species are distinctly different from the situation on other continents. Because of these differences, the epidemiology of BTB and zoonotic TB is antici­pated to be different from those on other continents and unique for the African continent. Diagnosing the infection remains one of the most critical issues and is an additional complicating factor because of the lack of sensitivity and specificity of the various currently available diagnostic techniques.

The primary mode of transmission of the disease is dependent on the individual species, and often varies, depending on the local animal husbandry practices, within countries. In cattle, the main mode of transmission is by inhalation, but in certain settings, per os infection is important. Aerosol transmission is particularly important in cattle in a confined airspace and with crowding, but it also occurs when they are exposed to droplets of contaminated water, droplets expelled during eructation when grazing, and by inhaling contaminated dust particles. The presence of lesions in the palatine tonsils indicates that per os infection may be more important in cattle than previously anticipated. However, per os infection appears to play a lesser role in the transmission of the infection, as much higher doses than with aerosol transmission are required for cattle to contract the disease. This mode of infection, however, is more commonly seen in goats and camels. Few calves, unless fed pooled milk containing M. bovis, contract the disease by consuming infected milk because of the low occurrence of the infection in the udder of cattle. Predators, such as lions, too are prone to contract the disease per os while eating M. bovis-infected organs and tissues. Licking, grooming, and suckling also may result in per os transmission. Other forms of transmission, such as the percutaneous route, appear to be important in lions and in kudus.

Several host-specific risk factors play a role in cattle contracting the disease, and these are often related to specific management practices. Commonly, higher preva­lences are encountered in urban and periurban smallholdings following uncontrolled movement of cattle between herds. But, contrary to the general expectation, in Africa, high prevalences can also be encountered in extensively managed cattle and other livestock because of the practice of housing them indoors at night in confined, roofed enclosures. Herd size, high animal densities, and the housing of cattle and other domesticated species are often proxies for the presence of and a high prevalence of the infection. Other herd-level risk factors in Africa include mixed rearing of domestic stock, such as goats, sheep, and camels, and intermingling with wildlife at the wildlife-livestock interface. Age is a risk factor and increasing numbers of infected animals are generally encountered with advancing age. This is particularly important in parts of Africa where cattle are kept for purposes other than the production of meat and milk; in those instances, the numbers of livestock owned are a sign of wealth, and they form part of a complex traditional social system. The role of gender as a predisposing factor varies according to management systems, and under specific circumstances, both cows and heifers, or oxen may present with higher prevalence rates. There were perceptions that breed may also play a role in susceptibility, and that African cattle breeds were more resistant to becoming infected with M. bovis, but ultimately it transpired that specific management prac­tices were more important in determining the prevalence of the infection in the different breeds. Immune status may determine susceptibility to infection, and this too is an important risk factor in Africa, particularly in those animals owned by transhumant ethnic groups. Immunosuppression is a characteristic of animals kept under poor hygienic conditions, those subjected to climatic and feed stress, crowding and poor ventilation, and those with coinfections with pathogens that characteristi­cally cause immunoincompetence.

Against the background of the very limited information about the extent and spread of BTB in Africa, it is clear that its distribution is not uniform. Its prevalence varies substantially between countries and also within countries where in certain regions the within-herd prevalence may be as high as 50%. This variation suggests the presence of hotspots of BTB within countries, and these may be the consequence of management practices, locality such as urban and periurban areas, and, in rural areas, factors such as communal water points and pastures and the aggregation of various herds during vaccination campaigns, at dip tanks, and at auction markets. Intermingling with wildlife maintenance hosts and contamination of the environ­ment by feces or exudates following which mycobacteria may remain alive for varying periods of time that may be as long as 6 weeks during the winter, are additional sources of M. bovis.

The main epidemiological factors of importance in Africa determining persis­tence and spread of the infection include: the growing population and increasing demand for milk and meat, pastoral and transhumance husbandry practices, increas­ing herd sizes, confinement with high animal densities, and the practice of housing animals in homes during the night for security purposes. These practices are likely to persist indefinitely, and unless addressed, will serve to perpetuate the presence of BTB throughout Africa.

The use of molecular epidemiological techniques has become common practice in the developed countries to analyze outbreaks and the origin and spread of BTB. It is only recently that these techniques have been applied in some countries in Africa, but sufficient information has been generated to provide a broad understanding of the epidemiological dynamics of the disease on the continent. Using spoligotyping, deletion analysis, MIRU-VNTR, and RFLP as typing techniques, an evolving pattern of the distribution and movement of different M. bovis types could be determined.

A number of pivotal events that occurred over the last four millennia most likely determined the distribution of the various M. bovis types. The major events include, particularly, the occupation by the Romans and Arabs during earlier times, the migration of various ethnic groups within Africa, the more recent colonization by European countries, and the consequence of the devastating rinderpest epidemic that decimated cattle herds and caused a bottleneck in their numbers toward the end of the nineteenth century. Typing confirmed the presence of unique indigenous African strains of M. bovis that existed before colonization that has for long been assumed to introduce BTB into Africa. Based on archeological findings, it appears that M. bovis was already present in cattle and other livestock on the European continent about 4000 years ago and that it may thus also have been present in cattle in certain regions of Africa at that time. The distribution of these African strains was probably determined by the migration of ethnic groups in Africa, including the Bantu, from Western Africa, and the Luo, Mande, and Omoti people in Eastern Africa. Currently, there are two groups of M. bovis in Africa, those that are unique to the continent and those introduced by the settlers from the colonial countries. This latter group, having been introduced after the rinderpest epidemic, appears to be, with the exception of those in Western Africa, the major types of M. bovis in most of the African countries. In addition to the Af1, Af2, and the putative Af3 and five clonal complexes, a number of unique African spoligotypes also occur, for instance, in Chad, Tunisia, Ethiopia, Uganda, and Zambia to the south. Two complexes, Af1 and the putative AF5, occur in Western Africa particularly in Chad, Niger, and Cameroon, while most of the spoligotypes that occur in low frequency tend to be country-specific. The Af2 clonal complex is limited to the countries in eastern East Africa, as are some spoligotypes referred to as the “indigenous East African spoligotypes.” The situation in Northern and South Africa is quite different, and in these regions, most of the spoligotypes belong to the Eur1 clonal complex, while in Madagascar all the isolates belong to the putative Af3 complex. Within this context, the dynamics and practices of livestock movements, the prevailing animal husbandry practices, and trade have had the biggest impact on the distribution of the various strains in the different African regions. Examples of these dynamics include the massive Sahel-Western African transhumant movement of humans and their livestock across international borders. These movements provide in-contact networks that promote the spread of the infection. In Eastern Africa, where the in-country profiles are more distinct, the effect of transhumance appears to be less, but it is, nonetheless, still apparent. Sudan appears to be the point of convergence of the two giant carousels of transhumant movement, and it may eventually play a pivotal role in the further dissemination of the various types of M. bovis in that part of Africa. In many of these countries, because of the changing dynamics in farming practices, and attempts to genetically improve the local breeds, there are also centrifugal and centripetal movements of cattle that, given the absence of any form of control of BTB, enhance the spread of the disease within these countries. Similar patterns of migration do not exist in Southern Africa, except for the localized migration in Zambia in the Kafue basin. In Southern Africa, as is the case in Zambia, and perhaps a developing trend in South Africa, the role of free-ranging wildlife in the epidemiology of the disease may become an important factor. Its role in the epidemiology of the disease in countries on the continent currently remains speculative because of the limited information about the disease dynamics in wildlife and their role in sustaining the infection in livestock. The extending wildlife-livestock interface, may yet, as in other countries, prove to complicate the control of BTB to the extent where it becomes impossible to control it. Application of molecular epidemiological tech­niques should equally address many of the questions about zoonotic TB, and the extent to which it occurs in those communities and groups of people at risk of contracting the infection.

A number of issues hamper progress in the management and control of zoonotic TB. In addition to the general assumption that it is not a problem in Africa, the lack of adequate disease control and eradication policies, the absence of continental reference databases and laboratory capacity for the isolation and genotyping of M. bovis, and the weak transdisciplinary and interlaboratory collaboration are major obstacles that will have to be overcome to get some degree of cooperation in regional and continental levels if the control of both BTB and zoonotic TB is to succeed in Africa.

Diagnosing BTB in live and dead animals is dealt with in Chap. 9. This is one of the most critical global impediments in the attempt to control BTB and zoonotic TB. The available tests and procedures all lack sensitivity and specificity, and are essentially herd, and not individual animal, tests. In spite of these deficiencies, some of the developed countries still managed to control and eliminate the disease from their cattle herds, albeit at a substantial cost, and over many years. In Africa, the lack of the technical capability and financial resources to use these tests commonly reduces the will of the politicians and regulatory authorities to control the disease.

As there is an international drive to eradicate human TB, by implication BTB and zoonotic TB must also be eradicated. Effectively eradicating the disease is dependent on the availability and use of detecting all the infected animals. In Africa, the lack of financial resources largely determines the diagnostic techniques that can be used, and meat inspection at slaughter remains the only affordable method by which the disease can be diagnosed and its spread and prevalence determined. Detecting BTB by meat inspection lacks sensitivity and specificity with the result that the informa­tion generated by its use is incomplete and unreliable. In many African countries, only a small percentage of carcasses for human consumption are processed, and most livestock are slaughtered informally and are not subjected to meat inspection. Using the data generated by the abattoirs largely becomes a process of counting numbers, without providing information that will augment the possibility of reducing the infection. There is a substantial variation in the epidemiology of BTB in individual countries and it is important that appropriate data are available to design effective control and eradication programs specifically for each individual country.

In addition to testing and applying the test-and-slaughter approach to deal with the disease, pasteurization of milk is the single most important intervention by which to reduce the prevalence of zoonotic TB. Although there is an increase in the provision of pasteurized milk, a large proportion of milk in Africa is still consumed raw, or after fermentation, particularly in rural areas where many ethnic groups are ill informed about the dangers associated with zoonotic TB and prefer raw instead of treated milk and meat. These practices remain a major risk, the extent of which is likely to increase with the increasing numbers of humans and cattle on the continent.

Tuberculosis is a disease without visible clinical signs, except for those in which it has reached an advanced stage. Even then, the signs are nonspecific and could be confused with those caused by a number of other diseases. This, too, is the situation in wildlife in which BTB may be asymptomatic, or cause nonspecific lesions that do not allow a definitive diagnosis. The intradermal skin tests (the single and compar­ative intradermal, and the caudal fold tests), and the INF-γ assay are the only ones approved by the OIE for use in cattle for diagnostic purposes. Although there is an increasing number of other tests, including serology, none of them has been vali­dated and their interpretation remains uncertain, and many are less sensitive and specific than the skin tests. With the exception of African buffaloes for which the skin tests have been validated, the same situation prevails in wildlife.

In addition to being prohibitively expensive in Africa, the use of the skin tests in cattle and other livestock is also impaired by a number of other factors. One of the biggest problems in Africa is the lack of adequate road networks and other infra­structure to do the tests, and the reluctance of cattle owners to return their cattle to the testing site to evaluate the reaction. Further impediments include the limited avail­ability of tuberculin, and the lack of trained human resources to do the tests. A number of other factors such as the impact of various types of stress and coinfection with diseases that cause immunosuppression and suppress the test reaction when doing the single intradermal test also play a role. Nonspecific reactions caused by infection with nontuberculous mycobacteria that cause nonspecific reactions in as many as 50% of animals tested in specific test cohorts are also major complicating factors in many parts of Africa.

Of all the available postmortal diagnostic techniques, meat inspection and nec­ropsy remain the least expensive and, if correctly applied, one of the most specific and sensitive of the available diagnostic tests. For it to be used effectively, investi­gators must be adequately trained because of the extensive inter- and intraspecific variation in the macroscopical and histopathological appearance of the lesions and the difficulty of detecting them when only single lesions are present. In addition, the issue of no visible lesions and latent infections complicates the matter even further. Commonly when doing routine meat inspection in abattoirs about 50%, and in some reports, up to 90% of BTB cases are not detected. The meat inspection protocols in Africa are mostly insufficient for the purpose, and many of the meat inspectors are not well trained. If meat inspection is to be used as a diagnostic technique, the working conditions of meat inspectors will have to be improved and their workload reduced, the physical facilities in which they work will have to be improved, and quality control measures will have to be instituted.

The physical appearance of the lesions of BTB is not that typical. Hence, a final diagnosis cannot be made on visual inspection alone, and confirmation of the diagnosis should be made by histopathological examination, or preferably, by culture, which is considered the gold standard for diagnosing TB. The success of culturing is dependent on a number of factors including the way in which the specimens are collected, their storage and transport, and the media on which they are cultured. Culture in itself is only a means of isolating the bacteria, and they must be identified and typed using specific techniques. The commonly used molecular typing techniques in Africa include RFLP, spoligotyping, deletion analysis, and MVLA-VNTR, but their use is limited because of the cost, and the lack of trained human resources and adequate laboratory infrastructure. The interpretation of most of these tests also has to be adapted for specific countries because of the variation in the molecular biological characteristics of the strains circulating in each of them. Using combinations of tests is one way of solving this problem, but it is necessary to combine different tests for different countries, based on the variation, and the molecular characteristics of the M. bovis strains in each of them. Since most of the initial diagnoses are made during postmortal examination, confidently diagnosing BTB in African wildlife is even more challenging given the marked variation in the appearance of the lesions in the various species. This is an important issue because of the anticipated importance of wildlife in the epidemiology of the disease in many countries on the continent and the importance of determining their role in the epidemiology of the disease.

In Chap. 10, the available options for the control of BTB are dealt with. Because of the complexity of the disease, the lack of reliable diagnostic techniques, the absence of an effective vaccine, and the expected duration and cost of eradication programs, it is almost impossible for most of the African countries to attempt controlling the disease. The test-and-slaughter approach that has been applied by the developed countries is, however, currently the only available option, and poor countries will have no alternative when attempting to control BTB, but to apply the process in a selective way by focusing on hot spots of the infection, and those animals in areas that are of epidemiological significance. Testing alone is not the solution to the problem. To have any hope of success, surveillance to determine the extent and distribution of the infection, and to allow risk factor analysis, increasing the knowledge and attitude of farmers and policy makers, improving the competency of veterinary and abattoir officials, and improving movement restrictions and biosecurity measures should be addressed. Whether the African countries will be able to do this is a moot point, and without the support of international agencies and NGOs, it is unlikely that they will be close to attaining the international goal of eradicating both human tuberculosis, and by necessity, BTB because of its zoonotic potential.

Chapters 11-23 are reports of the situation in 13 of the 54 countries on the continent. In many of them, BTB is recognized as a major animal health problem. The variation in the status of the disease, its economic impact, the application (or lack) of control measures, and the zoonotic role of BTB is probably an adequate reflection of the situation in those countries that are not represented. These chapters provide a focused rendition of the situation that varies from a total lack of informa­tion, to the more sophisticated control programs applied by South Africa.

The information provided also emphasizes the marked differences in husbandry practices, ethnic traditions, and mostly the lack of control of the disease because of the lack of movement control within and across international borders. In addition, the lack of dealing with known BTB infections by not removing infected animals from the system and allowing free movement of them within countries and across international borders further complicate the process. These country reports also provide some insight into the ethnic practices that enhance the risk of contracting zoonotic TB and the general lack of knowledge about the disease, its dynamics, and the risk that it poses to human health.

If the content of this book manages to create awareness of an important neglected disease on the continent and to stimulate some form of activity to address the problems caused by M. bovis infections, it would contribute substantially to increas­ing the health and welfare of the humans and the health and productivity of the animal populations in Africa. We believe that this book provides useful information that will provide policy makers and regulatory authorities with a sound basis to enable them to make better-informed decisions about the importance of the disease and the need for its control and eventual eradication from the continent.