Parasitic worms (helminths) are a diverse and geographically widespread group of organisms which are responsible for infecting millions of people throughout the world. Many of these parasitic helminths are either zoonoses (disease agents naturally transmitted between vertebrate animals and man) or have evolved from animal parasites. Helminthic parasitism may be responsible for asymptomatic, mild, severe and even lethal infections in humans and some vertebrate animals. Many of these helminth species are primarily resticted to tropical and subtropical areas and others have greater prevalence in warm climates. In Africa, parasitic helminths, many of which are zoonoses, are of significant public health importance, are responsible for economic losses, may hamper rural development programmes and generally slow down the pace of economic development. Human migration and movements due to the ever expanding population, wars, famine or modiciation of the environment, and the increased proximity of people to areas inhabited by a great diversity of wildlife species, make zoonoses of special interest in Africa.Patterns of transmissions of helminth parasites (in Africa) are highly influenced by social and cultural interactions and by the unique variety of wildlife and habitats. It is not surprising therefore that approaches to the study and control of parasitic zoonoses usually requires a complex intersectorial co-operation between medical and veterinary experts, parasitologists, biologists, zoologists, demographers, anthropologists and engineers. This book is a selective, rather than a comprehensive, compilation on parasitic helminths, with some emphasis on helminth zoonoses, particularly those which are important in the context of Africa. Furthermore, the importance of animal models has been highlighted for some helminth parasites. The title of this book strongly reflects the three areas, ie. parasitic worms, zoonoses and Africa, in which the work of one man, Professor George Stanley Nelson, has made a major impact over a 40 year period. This volume was conceived with George Nelson Nelson very much in mind and is dedicated to him on his retirement.The subject of the chapters strongly reflect areas where he contributed directly or indirectly, and all the authors have worked with him or been influenced by him.
