Preface

Africa, considered to be the cradle of humankind, is a vast continent characterized by the richness of and variation in its ecosystems and human and animal populations. It faces major challenges as part of the developing world, and many of the countries on the continent are of the poorest on the globe.

This book deals specifically with tuberculosis of animals in Africa and its zoonotic implications for human populations in the various countries. It is known that human tuberculosis was rife in Egypt at the time of the Pharaohs, and it is thought that tuberculosis in cattle existed in North Africa since ancient times. At that time, and even now, nomadic human-animal population movements seem to facil­itate the spread of the disease throughout various regions in Africa.

Tuberculosis is one of the major economically important global diseases of humans and animals. It is of as great importance in Africa as it is elsewhere and it is endemic in African countries that report their disease status to the WHO and the OIE. In many of the countries, confirmation of the causal agent and determination of species and strains are not practiced because of the lack of suitable laboratories and of inadequate financial, human, and material resources. In most of the African countries, available funds are allocated to dealing with more immediate devastating animal diseases such as rinderpest (now eradicated), CBPP, and foot-and-mouth disease. Bovine tuberculosis, however, remains important as it limits the ability of countries to participate in international trade in animals and animal products to countries that are free from the disease, or are in the process of eradicating it.

For many years, it has been assumed that colonization and the importation of foreign cattle resulted in the introduction and spread of bovine tuberculosis in Africa. However, recent research suggests that unique African strains of Mycobacterium bovis occur in Western and Eastern Africa, and it appears that the disease in cattle in Africa was present before the importation of bovine tuberculosis-infected foreign cattle from Europe and Australia. It does appear though that the introduction of the foreign strains of M. bovis contributed to the large diversity of M. bovis strains isolated from cattle across Africa.

Tuberculosis in animals is caused by a number of bacteria of the genus Myco­bacterium. It is a chronic, contagious disease and, dependent on the mycobacterial species, has a wide host range and various routes of transmission.

The epidemiology of tuberculosis in animals is complex, and is even more so in Africa, given the extreme variation in ecosystems, poor border control, and farming practices that vary from extensive to intensive and, in many instances, the movement of livestock over vast distances because of nomadism and transhumance.

In parts of Africa, more recently, spread of M. bovis to wildlife has become common, and in some instances, wildlife species became maintenance hosts of the disease. In this respect, the role of lechwe (Kobus leche) in Zambia and that of African buffaloes (Syncerus caffer) in South Africa, Zimbabwe, Tanzania, and Uganda are good examples. This development has serious consequences for coun­tries attempting control and eradication of the disease in domestic stock as it has been shown that when bovine tuberculosis occurs in a number of species in a complex ecological system, eradication by applying current control measures becomes impos­sible. Cross-border control of the movement of wildlife is even more difficult than that of livestock, and this movement may become a bone of contention in the development of the large number of trans-frontier parks that straddle the border of a number of southern African countries.

The increasing use of contemporary molecular techniques, such as VNTR, in African countries as presented in this book, provides greater insights not only into the status of bovine tuberculosis in African countries, but, moreover, the interrelat­edness of outbreaks across international borders.

The information provided by current African research presented by the different contributors to the book and the reports of different African countries provide a better understanding of the epidemiology of M. bovis, M. africanum, and other closely related pathogenic mycobacteria in cattle, wildlife, and zoonotic tuberculosis in Africa. This improved understanding should be utilized by policy makers and animal and human health authorities to improve their decision-making and chances of success when attempting to control and eradicate the disease in their respective countries. It is also clear that future activities aiming to control and eliminate tuberculosis in animals and humans should employ interdisciplinary collaboration between medical and veterinary medical professionals as embodied by the philoso­phy of the “One Health” approach.

Tuskegee, AL

Asseged B. Dibaba

Nicolaas P. J. Kriek

Charles O. Thoen

Onderstepoort, South Africa

Ames, IA