Urinary schistosomiasis surveillance in primary health care in South Africa.
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Date
1998
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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.
Description
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.
Keywords
Schistosomiasis--Epidemiology., Public health--KwaZulu-Natal., Schistosoma haematobium., Schistosomiasis--Prevention., Schistosomiasis--Diagnosis., Health education., Theses--Entomology.