Academic journal article Bulletin of the World Health Organization

Questionnaires for Rapid Screening of Schistosomiasis in Sub-Saharan Africa. (Public Health Reviews)

Academic journal article Bulletin of the World Health Organization

Questionnaires for Rapid Screening of Schistosomiasis in Sub-Saharan Africa. (Public Health Reviews)

Article excerpt

Introduction

Schistosomiasis is a widespread parasitic disease of the tropics that places an enormous toll on the public health of affected regions. Of the 200 million people infected worldwide, 85% of the burden is concentrated in Africa south of the Sahara (1, 2). In most epidemiological settings, the intermediate host snails cannot be controlled by cost-effective interventions, and in the absence of a vaccine, schistosomiasis control largely relies on chemotherapy, with praziquantel as the drug of choice (1). An important feature of the disease is its focal distribution (3). This results in a patchy distribution of risk, and communities across a region or country do not attach the same importance to schistosomiasis. Praziquantel is therefore not required everywhere and proper targeting is crucial, given the limited resources and the many other problems facing primary health care systems in sub-Saharan Africa.

The first step in targeting health interventions is to map the disease geographically and rank it according to the risk of infection and morbidity. In 1987, the first attempt to systematically map schistosomiasis on a global scale resulted in the Atlas of the global distribution of schistosomiasis (4). A more recent effort using geographical information systems highlighted the scarcity of data for Africa (5), and underscored the need for a rapid and inexpensive epidemiological assessment tool that can be fully integrated within existing administrative systems. Such a tool, relying on simple school questionnaires, was developed more than a decade ago for Schistosoma haematobium and has since been validated in a variety of ecological, epidemiological, and sociocultural settings across sub-Saharan Africa. More recently, the approach was extended to S. mansoni and its validity assessed in several large-scale studies.

This article is a comprehensive review of the experiences and evidence from sub-Saharan Africa with questionnaires for rapidly screening for schistosomiasis. The questionnaires can be used at both community and individual levels, and this approach allows communities with a high risk of schistosomiasis to be identified. Resources for controlling the parasite can thus be allocated in a more cost-effective way (6). We also discuss how this tool will contribute to a more sustainable and integrated system of control of schistosomiasis.

Questionnaires for diagnosing Schistosoma haematobium infection at a community level

The presence of blood in urine (haematuria) has been associated with S. haematobium infection since ancient times, but its use as an indirect indicator for this parasite was first investigated only two decades ago, in a study that simply asked community members living in Ghana and Zambia about their history of haematuria. These studies showed that haematuria was promising as an indirect indicator, but there was considerable variation in its diagnostic performance between the two settings (7).

Urinary schistosomiasis as illness was well perceived and correlated with infection in a rural community of the Kilombero District in the United Republic of Tanzania in the mid-1980s (8, 9). As a result, a district-wide study that emphasized rapid and inexpensive community diagnosis was initiated in 1986. The study aimed to identify high-risk communities, rather than infected individuals, because the highest priority for control was to target praziquantel chemotherapy in areas at greatest risk. A simple questionnaire that asked respondents whether they had experienced any of eight symptoms and eight diseases common in the area was developed and administered to all primary schools through the existing education system (10). The key features of this questionnaire are described in Box 1 (11, 12). Within six weeks, 75 of 77 schools returned completed questionnaires with a total of 6772 children interviewed. A mobile laboratory team then visited 56 schools for parasitological validation. …

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