Urban environment and intestinal parasitoses in the Sahel. A study in a Niamey District, Niger

Health and environment in Niamey a capital in Sahel, are particularly linke d owing to population growth, promiscuity and large pollution induced by hu man and animal excreta. One district, located in the centre of the town, was surveyed for drinking water quality (ammoniac and bacterial count) and use, as well as for the pr evalence of parasites through both a random sample (fixed tools with methio late-iodine-formaldehyde) and a systematic one (scotch-test). Water consumption was 16.5 litres/day/man from fresh water supplies (87%) a nd private wells (13%). Ammoniac measures were low in the wells but high in running water (pool and river). It was the same for faecal coliform bacter ia. These results give evidence of biotope faecal pollution. The random sam ple (322 persons, male/female seu ratio 0,85, average age 20,6 years) showe d a 42.1 % parasitic prevalence. Amoeba was the most frequent parasite (53. 6%); and Giardia (14.9%) was the most frequent pathogenic parasite. In the second sample (161 children under 10 years), 24.2% were carriers of oxyuris . This large intestinal parasitism without any change in connection with prev ious data in Niger; points to an important fecal contamination of the peopl e more by the way of "dirty hands" than consumption of drinking water: The parasites observed have a short biological cycle, not necessitating longter m maturation in the environment Those whose ova or larvae must complete the ir cycle outside have no possibility of suviving in Sahel, thanks to the be neficial effect of sunlight (heat and ultraviolet light). The inhabitants of this district seem to have adapted to intestinal parasit ism. But the occurrence of malnutrition linked to a new drought could lead rapidly to a very serious adverse result.