Epidemiology of Necator americanus hookworm infections in Xiulongkan village, Hainan Province, China: High prevalence and intensity among middle-agedand elderly residents

Hookworm is highly endemic to Hainan Province, an island located in the Sou th China Sea. To investigate the prevalence and intensity of infection in t he area, the village of Xiulongkan was surveyed between April and July 1998 . A cross-sectional study was conducted in which fecal samples of 80% of th e village residents (631 individuals) were tested for the presence of helmi nth eggs. Hookworm was the predominant intestinal helminth in Xiulongkan. w here it was determined that 60% of those tested were infected. Necator amer icanus was the predominant species of hookworm in this population. The prev alence of hookworm increased with age, and then leveled to a plateau for ag es 41 yr and up. This observation was in contrast to infections with Ascari s lumbricoides, where the highest prevalences occurred among school-aged ch ildren. Women had a significantly higher prevalence of hookworm than men an d this difference emerged in early adulthood. The intensity of hookworm inf ection also significantly increased with age, with the highest intensity in fections occurring among middle-aged and elderly residents. Females were mo re likely to have moderate or heavy infections, whereas males were more lik ely to have light infections. The rates of hookworm transmission are partic ularly high among the middle-aged and elderly residents of Xiulongkan.