Epidemiology of Hymenolepis nana infections in primary school children in urban and rural communities in Zimbabwe.

Fecal specimens were obtained on 3 occasions at 10-12 wk intervals from 315 children in 3 rural villages in Zimbabwe and from 351 children in the high-density suburbs of an adjacent small town. Specimens were examined qualitatively and quantitatively for eggs of Hymenolepis nana, and these were found in 142 (21%) children. Infections occurred more frequently in younger children in the urban area but in older children in rural areas. The prevalence in urban areas (24%) was higher than in rural areas (18%), and in urban areas infection correlated with low "hygiene scores" (determined by observation) and with the presence in the household of an infected sibling. The prevalence of infection in the 3 rural communities did not correlate with availability of water, number of households per toilet, with low "hygiene scores," or with the presence of an infected sibling. Treatment with a single oral dose of 15 mg/kg praziquantel cured 84% of the infected children. New or reinfections occurred more frequently in households that had an infected sibling in an urban but not rural setting. The study demonstrates distinct differences in the transmission of H. nana infection in rural and urban communities. The data suggest intrafamily transmission in urban areas, particularly in households with poor hygiene behavior, leading to primary infection early in life. In rural areas, the prevalence of infection and the incidence of reinfection were highest in children of school age, and there was little evidence for intrafamily transmission of the parasite.