The use of questionnaires and parasitological analyses to identify groups at low risk of becoming infected with bilharziasis and the factors that might contribute to this in a community in the endemic area in South Africa
Groups at low risk of becoming infected with Schistosoma haematobium, as well as factors minimising such a risk, were identified in a study in the Limpopo Province of South Africa. Urine samples were collected from 623 persons of whom 276 were males. Schistosome ova were isolated by filtering the entire urine sample through a VisserHelminth Filter®. The isolated ova were counted and expressed as numbers per 10 ml urine. Information with regard to age, sex, level of schooling, knowledge of the disease, history of previous anti schistosomiasis treatment, visits to the river and details of activities performed at the river was obtained from the people tested by means of a questionnaire. A peak in prevalence as well as intensity of infection in especially the males in the 3-9 and 10-14 age groups was found. In the 3-9 year age group the availability of a toilet was found to correlate well with the absence of schistosome infections while no such factors could be found in the 10-14 year and older than 23 year age groups. The availability of either a house or communal tap was identified as a factor that correlates well with the absence of infection in both males and females in the 15-22 year age group. Knowledge of the disease and bathing in the river were respectively identified as factors in females in the 3-9 and older than 23 year age groups, which correlate well with the absence of infection. The majority of males and females had low infection rates, while only 3,6% of the males and 2,7% of the females were heavily infected.