Comprising an editorial and seven articles, this special report provides an overview of health issues in these countries. The risk factors and modes of transmission for the most widespread tropical diseases (malaria, yellow fever, dengue fever, schistosomiasis, acute diarrhea, HIV infections and AIDS, meningitis) are briefly described, with a special focus on the Ebola virus disease epidemic in Zaire. The epidemiological transition currently underway in some of these countries is compared with the observed demographic transition. Changes in lifestyle—including, among other things, a significant rural exodus—have created new risk factors (malnutrition, alcohol and tobacco use, and in urban areas: violence, pollution). The inadequacy of health systems in addressing these new diseases necessitates the implementation of new health policies, with the assistance of international organizations and NGOs. Programs must take into account the specific needs of rural areas. Health risks for travelers in developing countries are addressed, along with preventive advice.