Diagnosis and Treatment of Schistosomiasis in Children in the Era of Intensified Control

Stefanie Knopp; Sören L Becker; Katrin J Ingram; Jennifer Keiser; Jürg Utzinger

Disclosures

Expert Rev Anti Infect Ther. 2013;11(11):1237-1258. 

In This Article

Abstract and Introduction

Abstract

In the current era of intensified and integrated control against schistosomiasis and other neglected tropical diseases, there is a need to carefully rethink and take into consideration disease-specific issues pertaining to the diagnosis, prevention, control and local elimination. Here, we present a comprehensive overview about schistosomiasis including recent trends in the number of people treated with praziquantel and the latest developments in diagnosis and control. Particular emphasis is placed on children. Identified research needs are offered for consideration; namely, expanding our knowledge about schistosomiasis in preschool-aged children, assessing and quantifying the impact of schistosomiasis on infectious and noncommunicable diseases, developing new antischistosomal drugs and child-friendly formulations, designing and implementing setting-specific control packages and developing highly sensitive, but simple diagnostic tools that are able to detect very light infections in young children and in people living in areas targeted for schistosomiasis elimination.

Introduction

Schistosomiasis is a chronic neglected disease of poverty caused by blood flukes of the genus Schistosoma.[1–3] Hence, schistosomiasis mainly affects people who live in deprived or marginalized communities in the tropics and subtropics. According to the Global Burden of Disease Study 2010 (GBD 2010), schistosomiasis ranks third after leishmaniasis and soil-transmitted helminthiasis among the neglected tropical diseases and is responsible for an estimated 3.3 million disability-adjusted life years.[4] In 2012, the WHO announced the new goals for 2020, namely to eliminate several of the neglected tropical diseases and to intensify control of other neglected tropical diseases, so that they no longer pose public health problems.[5] WHO gets support from public (e.g., Ministries of Health) and private partners (e.g., pharmaceutical companies) and nongovernmental organizations. These partners collectively signed the London Declaration and are thus committed to tackle neglected tropical diseases including schistosomiasis.[301] Specifically, the aim for schistosomiasis-endemic countries is to periodically administer the antischistosomal drug praziquantel to populations at risk of infection and hence prevent morbidity. This strategy is phrased 'preventive chemotherapy.' The primary target, as endorsed by Member States in World Health Assembly (WHA) resolution 54.19 in 2001 – but still far from being met – is to treat at least 75% and up to 100% of school-aged children (SAC) who are at highest risk of morbidity.[6,7] In May 2012, WHA resolution 65.21 has been endorsed, acknowledging progress in schistosomiasis control and hence considering elimination as the next logical step and an attainable goal in some low-endemicity areas.[8] Hence, Member States are encouraged to work toward the interruption of transmission and to initiate elimination campaigns wherever appropriate.[8] Additionally, the Schistosomiasis Consortium for Operational Research and Evaluation is currently supporting a multiyear integrated program aiming at schistosomiasis elimination on Zanzibar.[9] Lessons learnt will be important for shaping the elimination agenda.[10] Although the primary tool for large-scale schistosomiasis control programs is preventive chemotherapy,[11] Member States and the international community should not only provide means for treatment, but instead improve the water and sanitation infrastructure, alongside setting-specific hygiene interventions and snail control.[8,12]

In this review, we summarize the epidemiology of, and morbidity due to, the three main Schistosoma species infecting man. The centerpiece of our review focuses on tools and strategies to diagnose, prevent, treat and control/eliminate schistosomiasis. In view of intensified control efforts, we highlight available drugs and regimens, different control approaches, novel diagnostic tests and the potential impact of schistosomiasis on co-infections and comorbidities due to HIV/AIDS, tuberculosis, malaria and intestinal protozoa infections. Since children are the main carriers and spreaders of schistosomiasis, particular emphasis is placed on this age group with child-related aspects discussed in detail toward the end of each subchapter.

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