Index of potential contamination for schistosomiasis

Schistosomiasis occurs under a wide variety of climatic, geographical and o ther conditions. The basic reason for the transmission of schistosomes is, however, the low level of sanitation in endemic areas with the result that faeces or urine, or both, containing schistosome eggs get into water that c ontains freshwater snails susceptible to infection. Unfortunately, the degr ee of contamination of natural habitats with schistosome ova is difficult t o estimate; consequently, there are few data on how much contamination, rel ative to a defined snail population density, is necessary to initiate or ma intain transmission of schistosomiasis. This article discusses a little-use d method to estimate the degree of contamination or transmission - the inde x of potential contamination (IPC). The expected changes in IPC after prazi quantel treatment will be considered, as well as the level of reduction in IPC that might be needed to affect transmission or reduce morbidity.