Academic journal article Bulletin of the World Health Organization

Rapid, Low-Cost, Two-Step Method to Screen for Urinary Schistosomiasis at the District Level: The Kilosa Experience

Academic journal article Bulletin of the World Health Organization

Rapid, Low-Cost, Two-Step Method to Screen for Urinary Schistosomiasis at the District Level: The Kilosa Experience

Article excerpt

Introduction

Schistosoma haematobium is endemic in 43 of the 52 African states in the African, European, and Eastern Mediterranean Regions of WHO [1]. Only 11 of these countries have so far set up nationwide control programmes, while three more have completed comprehensive screening activities to gain an overview of the distribution and importance of the disease. In the remaining 29 endemic countries, the presence of the disease has been unsystematically reported, usually by many different sources over a few decades [2], and large areas remain whose urinary schistosomiasis status is unknown.

Because of the marked focal nature of transmission of schistosomiasis [3], a comprehensive epidemiological investigation has to be carried out before rational decisions can be made about controlling the disease. It is essential to concentrate available resources on detecting, treating, and protecting patients in high-risk areas, rather than screening and protecting mostly unaffected individuals in low-risk areas [4]. In this regard, the threshold of positivity, above which the use of specific financial and human resources is justified, is critical and has to be defined according to the results of longitudinal morbidity surveys and assessment of community priorities. Recent reviews of the medical and socioeconomic impact of schistosomiasis [5,6] have indicated that forth both intestinal and urinary schistosomiasis no simple criteria exist for defining this positivity threshold. As far as the setting of health priorities by communities is concerned, one tanzanian study has compared the disease perception of the leaders of political parties and school head-teachers with the results of parasitological surveys; this permitted definition of a high-priority threshold, a prevalence above which almost all respondents placed urinary schistosomiasis among the top four diseases for control [7].

Once such a threshold has been defined, a rapid and cost-effective diagnostic strategy should be worked out to classify the community units (schools, hamlets, villages, political units, etc.) into high-risk or low-risk groups. In the latter, any control, if needed, should be restricted to case detection within the existing health services [8]. In the high-risk groups, active case detection for treatment and other control measures could be introduced. In the United Republic of Tanzania school questionnaires proved to be rapid and very cost-effective for this preliminary, area-wide screening [7]; however, the results obtained permitted neither quantification of the infection rate nor the identification and treatment of infected children. A second step, consisting of application of a simple quantitative test, was therefore necessary.

Because of their operational simplicity, reagent sticks for the detection of blood in urine were considered to be the ideal tool for this purpose. Such sticks are highly specific, and, although they are less sensitive than urine filtration for detecting S. haematobium infections [9,10], recent studies have shown that the cases not detected were mostly very light infections (< 10 eggs/10 ml) and that reagent sticks are as efficient as urine filtration in detecting infections of [is greater than or equal to] 50 eggs per 10 ml [11]. (a) The sticks also have higher predictive values for macropathology visualized using sonography [12], and should therefore play a major role in a morbidity control approach [11-13]. (a) The operational value of reagent sticks for a control programme based on primary health care (PHC) has already been demonstrated in a study on Pemba Island [13].

Although PHC-driven schistosomiasis control should be integrated into existing health care structures [1], the health personnel in most endemic areas are overwhelmed by day-to-day clinical duties and can hardly be asked to perform systematic community screening. In the present study, we therefore asked non-health personnel to carry out the reagent stick testing. …

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