Neglected tropical diseases: equity and social determinants 1 8 Jens Aagaard-Hansen and Claire Lise Chaignat Contents Water, sanitation and household-related factors 147 Environmental factors . 147 8.1 Summary . 136 Migration . 148 8.2 Introduction . 136 Sociocultural factors and gender . 148 Neglected tropical diseases. 136 Poverty as a root cause of NTDs. 148 Equity aspects of neglected tropical diseases . 138 8.6 Implications: measurement, evaluation Methodology . 138 and data requirements . 150 8.3 Analysis: social determinants of Risk assessment and surveillance. 150 neglected tropical diseases . 139 Monitoring the impact . 150 Water and sanitation. 139 Knowledge gaps . 151 Housing and clustering . 140 Managerial implications and challenges . 152 Environment . 141 8.7 Conclusion . 152 Migration, disasters and conflicts . 141 Sociocultural factors and gender . 142 References . 153 Poverty . 143 Table 8.4 Discussion: patterns, pathways and Table 8.1 Relationship of the 13 NTDs to entry-points . 144 the selected social determinants and the five 8.5 Interventions . 146 analytical levels. 145 1 The authors would like to acknowledge the valuable input of reviewers (especially Susan Watts and Erik Blas), and Birte Holm Sørensen for her comments regarding the potential of social determinants as indicators of multiendemic populations. Also thanks to staff members of the WHO Department of Neglected Tropical Diseases for their support and advice. Neglected tropical diseases: equity and social determinants 135 8.1 Summary Consequently, poverty should be addressed both in gen- eral poverty alleviation programmes for NTD-endemic The neglected tropical diseases (NTDs) are very het- populations and more particularly by ensuring afford- erogeneous and consequently the analysis of inequity able treatment. and social determinants is extraordinarily complex. The result is a pattern where the various NTDs are clus- Action 6: Setting up risk assessment and sur- tered in different ways. This leads to six recommended veillance systems. The NTDs are characterized by actions, all of which relate mostly to preventive and their focality determined by the complex combinations promotive measures. In each case the right of vulner- of environmental and social determinants. Pockets of able and marginalized groups to be heard and to exert multiendemic population segments are likely to “disap- political influence should be ensured. pear” within statistical averages and must be identified as a means to address inequity and in order to direct Action 1: Addressing water, sanitation and house- curative or preventive interventions to NTD hot spots, hold-related factors (the “preventive package”). thereby increasing efficiency. Cross-disciplinary risk The analysis shows overwhelming evidence of how the assessment and surveillance systems should be estab- intermediary social determinants of water and sani- lished based on combinations of epidemiological, tation, and housing and clustering, determine NTDs. environmental and social data, providing not only early Consequently, there is a need to address these risk fac- warnings for epidemics, but also evidence for long- tors in endemic communities to provide sustainable term planning under more stable conditions. prevention for clusters of NTDs. Action 2: Reducing environmental risk factors. 8.2 Introduction Environmental factors are essential determinants for many of the NTDs. These factors are often introduced by humans, either directly or indirectly. Planning based Neglected tropical diseases on health impact assessments for new projects and miti- gating revisions of existing schemes are needed in order This chapter considers the so-called neglected tropi- to control NTDs. cal diseases (NTDs) (1–3), focusing on the 13 diseases covered by the World Health Organization (WHO) Action 3: Improving health of migrating pop- Department of Neglected Tropical Diseases: Buruli ulations. Migration encompasses the movements of ulcer, Chagas disease, cholera, dengue fever (including nomads, labour migrants, people subjected to forced dengue haemorrhagic fever), dracunculiasis, lymphatic resettlement and refugees from natural disasters or filariasis, human African trypanosomiasis, leishmaniasis, armed conflict. Their movements influence exposure leprosy, onchocerciasis, schistosomiasis, soil-transmitted and vulnerability to some NTDs, and access to health helminths and trachoma. From a biomedical perspec- care systems is reduced. The particular NTD issues that tive, the 13 NTDs are very heterogeneous. Box 8.1 relate to these groups should be addressed in ways that gives a brief description of each disease. are tailored to local conditions (patterns of morbidity, mobility, environmental and sociocultural factors). An aggregated measure of 11 of the 13 NTDs (omit- ting cholera and dengue fever) ranks sixth among the Action 4: Reducing inequity due to sociocul- 10 leading causes of disability-adjusted life years,2 ahead tural factors and gender. Sociocultural factors, of malaria and tuberculosis (4 ). Estimates are, how- which are often closely linked to gender roles, interact ever, uncertain, and recent studies argue that incidences with NTDs in various ways. In some cases NTDs incur and impacts of schistosomiasis (5 ) and trachoma (6 ) added burdens due to stigma, isolation and other neg- have been underestimated. Researchers have mapped ative consequences. These factors may also reduce the the global distribution of trachoma (7 ) and lymphatic acceptability of health services, leading to differential filariasis, onchocerciasis, schistosomiasis and soil-trans- health care outcomes. There are unexplored potential mitted helminths (8 ). Brooker et al. (9 ) have attempted advantages in addressing these issues from a multidis- to map helminth infection in sub-Saharan Africa. De ease perspective. Silva et al. (10 ) add an interesting time dimension to the analysis of soil-transmitted helminths, showing the Action 5: Reducing poverty in NTD-endemic trend 1994–2003. populations. Poverty emerges as the single most con- spicuous social determinant for NTDs, partly as a structural root determinant for the intermediary social determinants and partly as an important consequence 2 Disability-adjusted life years (DALYs) reflect a combination of the of NTDs, either directly (leading to catastrophic health number of years lost from early deaths and fractional years lost expenditure) or indirectly (due to loss of productivity). when a person is disabled by illness or injury. 136 Equity, social determinants and public health programmes BOX 8.1 Brief description of neglected tropical diseases Buruli ulcer is caused by a bacterium (Mycobacterium ulcerans) and is clinically characterized by big ulcers that lead to disfiguration and sometimes loss of limbs. There are indications that infection is based on direct contact to the environment, without vectors or animal reservoirs playing a role. Treatment is expensive and involves surgery and hospitalization. Chagas disease is caused by a protozoon (Trypanosoma cruzi). It is transmitted by various species of “kissing bugs” (Triatominae) that live either in houses or in forests, or via blood transfusion. Domestic and wild animals play important roles as animal reservoirs. The symptoms develop gradually, mainly affecting the heart and the intestines. The main control measure is vector control. The disease is confined to Latin America. Cholera is caused by different types of Vibrio bacteria. Water and food contaminated with human faeces are the main sources of infection. Cholera cases are characterized by profuse diarrhoea, and rehydration is the main treatment. Cholera is present worldwide though rarely in parts where the sanitary infrastructure is of adequate standard. Dengue fever is caused by an arbovirus and transmitted by mosquitoes (Aedes aegypti). The symptoms are fever, headache, musculoskeletal pain and rash. If the patients are reinfected with another serotype there is a risk of dengue haemorrhagic fever. Within recent decades the disease has spread from Asia to tropical areas in all parts of the world. Dracunculiasis (guinea-worm disease) is caused by a worm (Dracunculus medinensis), the larvae of which enter the human body through drinking water containing the tiny crustaceans that carry the larvae. Adult female worms erupt from the skin to shed eggs. Filtering water and surgical removal of adult worms are important control measures. Though much progress has been made, there is still a handful of endemic countries in Africa. Human African trypanosomiasis (sleeping sickness) is caused by various Trypanosoma spp. The disease is transmitted by tsetse flies (Glossina spp.), and various types of animals (pigs, cattle and antelopes) serve as reservoirs. The central nervous system is affected and treatment with drugs is difficult and expensive. Control is largely aimed at vectors. Leishmaniasis is caused by various protozoa (Leishmania spp.) transmitted by female sandflies (Phlebotomus and Lutzomyia spp.). Symptoms range from cutaneous or mucocutaneous cases to lethal visceral cases (in India known as kala-azar) and treatment is difficult. Apart from South Asia, animal reservoirs include rodents and canines. Leishmaniasis is widespread in tropical and subtropical areas. Leprosy is caused by a bacterium (Mycobacterium leprae) that affects the skin and nerves. The disease develops slowly and can lead to severe dysfunction and disfiguration. The main route of infection is from person to person,