Urinary schistosomiasis surveillance in primary health care in South Africa.

Abstract

A multifaceted Schistosoma haematobium study aimed at assessing five different diagnostic techniques of surveillance was conducted. Their use in varying operational circumstances with particular reference to Primary Health Care was conducted in three areas of varying prevalence of disease namely; Mpolweni Mission (44.1%), Empangeni (30.3%) and Verulam (72.0%), KwaZulu-Natal, South Africa. This study incorporated both theoretical and applied components. The theoretical components included freshwater snail surveys, review of literature of S. haematobium diagnostic techniques and an assessment of five diagnostic techniques with particular emphasis on diagnostic performance and cost analyses. Added to these components was migration and the assessment of the prevalence of disease amongst occupants of informal settlements in and around the greater Pietermaritzburg city centre. The applied component included the initiation of a holistic S. haematobium control programme based along the World Health Organisation Guidelines. The study provided insight into several of the countries health issues relevant to both schistosomiasis and other diseases and highlighted weaknesses that may hinder the successful implementation of the current National Framework for Parasite Control. The presence of urban schistosomiasis was noted for the first time in the city of Pietermaritzburg. The present schistosomiasis distribution could be influenced by the rural-urban migration that is impacting upon major metropolitan areas. Without intermediate host snail surveys and schistosomiasis prevalence surveys amongst members of the population, the real geographic distribution of the disease will not be known. The diagnostic methods that were compared included sedimentation, filtration, three brands of chemical urinalysis strips, urine colour scales and an indirect questionnaire. Sensitivity, specificity, positive predictive, negative predictive and efficiency values were determined. Using these values, diagnostic performance ranges were established. The ranges were influenced by the cut-off values used, technique and prevalence and intensity of infection of the study area. The chemical urinalysis strips at cut-off 10erythrocyes/μl (73.7% - 93.2%) were highly sensitive whereas urine colour scales (97.1% - 99.4%) and indirect questionnaire (80.4% - 90.3%) were highly specific. The relationship between the community prevalence rates measured by all five techniques varied significantly. A cost-analysis of the techniques/sample demonstrated a wide price range (20c - R4.32). Therefore their use would be dictated more by the availability of funding than by any operational advantages each individual technique may have demonstrated. Within the public health services a need for: (1) staff training programmes, (2) core staff based within the PHC system that is dedicated to parasite control and (3) a strengthening of infrastructure was demonstrated. These may be achieved via workshops, improved communication, education courses, specific time allocation to parasite programmes i.e. parasite week, project co-ordinators and the designation of tasks.