Epidemiology of poly-parasitism. I. Occurrence, frequency and distribution of multiple infections in rural communities in Chad, Peru, Afghanistan, and Zaire.

Parasitic diseases are predominantly rural diseases. They are often associated with poverty, illiteracy, poor sanitation and high risks of exposure to environmental and biological hazards. Because these factors are also essential determinants in the epidemiology of a variety of other infections with quite different etiologies, occurrence of multiple infections in the same people is common. In the tropics, polyparasitism may involve diseases of major public health inportance such as malaria, schistosomiasis, filarial infections, trypanosomiasis, and others. The paper presents data on the frequency and types of multiple infections with different parasitic and other infectious agents for thirteen villages of Chad, Peru and Afghanistan. The age and sex patterns of a number of observed combinations of parasitic and other diseases are shown for different ecological zones. Concomitant infections with up to five species of filarial worms are found in residents of villages in the Congo River Basin of Zaire. The specific types of combinations of these infections vary from place to place and appear to be closely linked to ecological factors.