This review assesses the impact which animal populations, or their health status, may have on our environment. The review is divided into two parts and includes sixteen papers by various experts on this subject. The first is devoted to relationships between the multiplication of various animal populations and the equilibrium of natural environments. The papers in this section show how animals participate in maintaining this balance and how it can be disrupted by certain human interventions. There is special reference here to Africa and Asia. The problem of pollution of towns and countryside by growing numbers of animals is also discussed.
Part two is devoted to relations between pathogens and the environment, and the conditions under which pathogens develop, circulate and survive. Details on the persistence of viruses and bacteria in soil and water are also provided.