Participatory epidemiology is a branch of veterinary epidemiology that uses a combination of practitioner communication skills and participatory methods to involve animal keepers in the analysis of animal disease problems, and the design, implementation and evaluation of veterinary programmes and policies. Much of the early development of participatory epidemiology occurred in remote areas of Africa, where conventional veterinary services were limited, but where pastoralists possessed rich indigenous knowledge on animal diseases. This book presents some of the early studies on participatory epidemiology in East Africa, and assesses the validity and reliability of the approach by comparing information derived from adapted participatory methods with conventional veterinary investigation and epidemiological information. Field research with pastoralist communities in South Sudan, Kenya and Tanzania is described, covering cattle diseases such as "chronic wasting", trypanosomiasis, and foot and mouth disease. These validation studies demonstrated why participatory epidemiology was an important approach for improving livestock disease control and human welfare in resource-poor settings.