The distribution of common intestinal nematodes along an altitudinal transect in KwaZulu-Natal, South Africa.

In order to study the effect of climate and topography on the distribution of common, intestinal nematodes in schoolchildren, changes in prevalence were investigated along an altitudinal transect from approximately 50 m above sea level (asl), near the coast, to approximately 1700 m asl, in the foothills of the Drakensberg Mountains, KwaZulu-Natal, South Africa. These changes were related to several permutations of temperature, rainfall and evaporation, using univariate and multiple regression analyses. A total of 693 primary schoolchildren aged between 7 and 15 years was examined from six communities along the 150-km transect. Changes in the prevalence of Trichuris trichiura were significantly correlated with temperature-derived variables whereas those of Ascaris lumbricoides and Necator americanus were correlated with rainfall-derived variables. A total of 17 parasite species was recovered along the transect but polyparasitism was negatively correlated with altitude.