The human environment, occupation, and possible water-borne transmission of the human hookworm, Necator americanus, in endemic coastal communities of the Niger Delta, Nigeria

Abstract

A 15-month longitudinal study was carried out in four riverine communities of the Niger Delta to ascertain the impact of the environment and occupation on the transmission and infection pattern of the human hookworm Necator americanus. A total of 925 (50.10%) individuals were found to be infected. Male and female infection rates were 54.26% and 47.96% respectively. The difference was statistically significant (P less than 0.05). The prevalence of infection, the egg counts, and the seasonal incidence were related to the occupations and mode of transmission. The highest occupation prevalence of 60.92% occurred among the fishermen through water-borne transmission, while prevalence rates of 52.96% and 52.4% were recorded respectively through soil transmission. The difference between fishermen's prevalence and farmers' prevalence was statistically significant (P less than 0.01). Farmers' egg counts varied from 1,500 eggs per gram (epg) in the dry season to 7,500 epg in the rainy season. Fishermen's egg counts ranged from 3,000 epg in the rainy season to 8,000 epg in the dry season. The difference was not significant (P greater than 0.05). Among farmers the highest monthly incidence of 25% occurred in June, while the highest incidence of 35% occurred in fishermen in April. Incidence of infection among fishermen remained significantly higher (P less than 0.05) than in other occupation groups during the dry season months. Water-borne transmission of hookworm probably increases the incidence and egg counts among fishermen during the dry season.