Towards effective prevention and control of helminth neglected tropical diseases in the Western Pacific Region through multi-disease and multi-sectoral interventions
Graphical abstract
We describe a new approach to helminth neglected tropical diseases control: multi-disease, multi-sectoral interventions. A framework for disease, sector and activity identification is proposed.
Introduction
Neglected tropical diseases (NTDs) are a diverse group of diseases caused by a variety of pathogens whose distribution and local prevalence are intimately linked to conditions of poverty (Feasey et al., 2010, Hotez et al., 2007, Utzinger et al., 2012). Indeed, NTDs are the most prevalent diseases among the 2.7 billion people who currently live on less than US$ 2 per day (Liese et al., 2010). While NTDs do not cause mortality on a scale comparable to other communicable diseases such as malaria, tuberculosis and HIV/AIDS, the disability, human suffering and societal impact attributable to NTDs are considerable (Murray et al., 2012). NTDs cause sequelae such as anaemia (e.g. hookworm infection), blindness (e.g. trachoma), malnutrition (e.g. soil-transmitted helminthiasis), intellectual and physical growth retardation (e.g. schistosomiasis), damage to internal organs, and long-term physical disability and disfigurement that lead to stigmatization (e.g. lymphatic filariasis and leprosy) (Hotez et al., 2007, Utzinger et al., 2012, Weiss, 2008). Recent research also suggests that infections with certain NTDs may increase the vulnerability to other infectious diseases, such as malaria and HIV/AIDS (Emerson et al., 2008, Gyapong et al., 2010, Hotez et al., 2006, Secor, 2012), and contribute to the chronic disease burden (Tanowitz et al., 2009).
Although medically and epidemiologically diverse, NTDs share certain important characteristics that allow them to thrive in conditions of poverty, while remaining rare among affluent populations. As a consequence, NTDs are concentrated almost exclusively among impoverished populations with precarious access to clean water and improved sanitation and unsafe hygiene practices. Such groups often inhabit geographic areas highly marginalized by the health sector and have scant access to other basic services (Holveck et al., 2007, Hotez et al., 2006, Molyneux et al., 2005, Schratz et al., 2010). The impact of NTDs on individual health and societal performance furthers the entrenchment of poverty by trapping communities in poor health, resulting in decreased economic potential (Conteh et al., 2010, King, 2010, Utzinger et al., 2011). For example, chronic schistosomiasis japonica in the Philippines causes the loss of an estimated 45 days of work per infected person every year, demonstrating the appreciable social and financial burden of NTDs (Blas et al., 2006). On a national scale, there is evidence for a correlation between the average national intelligence quotient (IQ) and high parasite stress, perhaps because the energetic cost of the parasite burden redirects energy away from brain development (Eppig et al., 2010).
In the absence of population-based preventive and curative measures, most NTDs occur at stable levels of endemicity. NTDs thus generally do not cause epidemiological or public health emergencies, conspicuous morbidity or immediate mortality, and hence, NTDs are often not of high priority for policy makers, and are usually not subject to compulsory reporting. As a consequence, NTDs are not perceived as major public health problems compared to epidemic-prone diseases, such as influenza, which explains that they draw little attention from the media and public sector (Ehrenberg and Ault, 2005, Hotez et al., 2006). The minimal threat that NTDs present to high-income populations also renders the development of drugs, diagnostics and vaccines relatively unprofitable (Cohen et al., 2010, Ehrenberg and Ault, 2005, Keiser and Utzinger, 2012, WHO, 2010b).
The World Health Organization Regional Office for the Western Pacific (WHO-WPRO) groups together 37 countries and areas, stretching from China and Mongolia in the North and West, to New Zealand and the Pitcairn Islands in the South and East. The region is home to a range of NTDs, many of them caused by helminths. Soil-transmitted helminthiasis, schistosomiasis, lymphatic filariasis and food-borne trematodiasis combined form a group of infections known as helminth NTDs. These helminth NTDs put the highest number of people at risk of infection and cause the highest burden due to NTDs in the region. Table 1 provides an overview of the helminth NTDs covered in the current article. Additional NTDs occur in the Western Pacific Region, but are not considered in this paper (Fürst et al., 2012, Hotez and Ehrenberg, 2010, WHO, 2010b).
To successfully control and prevent helminth NTDs, the attention of all key stakeholders is needed as sustaining reduced prevalence rates following mass drug administration requires integrated approaches (Utzinger and de Savigny, 2006). Multi-disease, multi-sectoral interventions may offer an opportunity for sustaining control efforts and achieving, in some instances, elimination. In this paper, we explore the feasibility of a multi-disease and multi-sectoral package of interventions for preventing and controlling helminth NTDs in a sustainable and cost-effective manner. We review current strategies for helminth NTD control, and identify activities of different sectors that are likely to have a significant impact on one or more helminth NTDs. In addition, we discuss our experience and the challenges inherent in multi-sectoral collaboration.
Section snippets
Preventive chemotherapy and other strategies
As helminth NTDs affect large numbers of people and most infections are concentrated in the poorest population segments, their prevention and control must rely on low-cost and practical tools that can easily be deployed to large populations, and require limited technical skills. In their first global report on NTDs, the WHO recommended five specific public health strategies for the prevention and control of NTDs: (i) preventive chemotherapy; (ii) intensified case management; (iii) vector
Identification of multi-disease, multi-sectoral interventions
To determine the potential of multi-disease, multi-sectoral interventions for the prevention and control of helminth NTDs in the Western Pacific Region, a series of matrices was developed to identify and visualize synergies between programmes. The activities and interactions between sectors are complex and may vary between specific geographic and socio-political settings. Programmes from each sector must, therefore, be systematically examined at the activity level in order to identify potential
Helminth NTD co-endemicity maps
Fig. 1, Fig. 2 visualize the co-endemicity of soil-transmitted helminthiasis, schistosomiasis, lymphatic filariasis and food-borne trematodiasis in the Philippines and the Lao People's Democratic Republic. In the Philippines, these four diseases are widely endemic, with the highest risk of co-endemicity in the eastern and southern provinces. Five provinces (Agusan del Norte, Compostela Valley, Leyte, Sorsogon and Surigao del Norte) are co-endemic for all four NTDs, and sixteen provinces for
Discussion
Opportunities and challenges to multi-sectoral coordination and collaboration are not confined to helminth NTD control alone. The importance of extrinsic determinants of health and the challenges of engaging partners with a different focus has been recognized before, including in a number of public health interventions focussing on health equity, non-communicable disease prevention, tobacco control, and environmental health (Prüss-Üstün, 2006, WHO-WPRO, 2009c, WHO, 2009, WHO and PHAC, 2008).
Conclusions and next steps
The matrix exercise evaluated the impact of a wide range of activities implemented by multiple sectors with regard to their potential impact on a set of selected high-burden helminth NTDs. The mapping of the overlaps in helminth NTD endemicity demonstrated the considerable scope for targeting multiple helminth NTDs in the same area. This position paper aims to draw attention to multi-sectoral collaboration for the sustainable control and prevention of these helminth NTDs. Preventive
Acknowledgements
This paper was developed following a series of consultations, discussions and contributions from colleagues from a number of institutions, including managers and staff from the WHO Regional Office for the Western Pacific. The authors thank the participants of the informal consultation on novel approaches to the prevention and control of NTDs as well as the Special Programme for Research and Training in Tropical Diseases (TDR) for offering technical advice and opinions on the proposed
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2014, The Lancet Infectious DiseasesCitation Excerpt :Transmission is ongoing and signs suggest emergence or re-emergence for many of the food-borne parasitic zoonoses, echinococcosis, and dengue.21,40,44 For NTDs whose transmission is strongly linked to the environment (eg, schistosomiasis and echinococcosis), an integrated, multisectoral approach is necessary to achieve elimination.24,45,46 Continuous improvements in living standards, placing an emphasis on access to clean water, adequate sanitation, and greater hygiene, will effectively contribute to the reduction of NTDs when transmission is mainly governed by social and cultural factors (eg, soil-transmitted helminthiasis).47,48