Viewpoint Rescuing the bottom billion through control of neglected tropical diseases Peter J Hotez, Alan Fenwick, Lorenzo Savioli, David H Molyneux Lancet 2009; 373: 1570–75 People in the bottom billion are the poorest in the world; fi lariasis; most are adults and have lymphoedema, Sabin Vaccine Institute and they are often subsistence farmers, who essentially live hydrocele, and disfi guring elephantiasis.3 Trachoma and George Washington University, on no money and are stuck in a poverty trap of disease, onchocerciasis arise in about 84 million and 37 million Washington, DC, USA confl ict, and no education.1,2 One of the most potent people, respectively.3 In addition to these seven diseases, (Prof P J Hotez MD); Schistosomiasis Control reinforcements of the poverty trap is the neglected the vector-borne arboviral and protozoan diseases, Initiative, Imperial College tropical diseases (panel 1).3 Almost everyone in the including dengue, leishmaniasis, Chagas disease, and London, London, UK bottom billion has at least one of these diseases. Several human African trypanosomiasis, can result in high (Prof A Fenwick PhD); diseases coexist in 56 of 58 countries that are home to mortality in some disadvantaged areas. Department of Control of 3 Neglected Tropical Diseases, the people in the bottom billion. Here we outline The seven main diseases often cluster in the same rural World Health Organization, low-cost opportunities to control the neglected tropical geographic regions (fi gure 1), where commonly one Geneva, Switzerland diseases through preventive chemotherapy, and propose person is concurrently infected with several of the seven (L Savioli MD); and Centre for fi nancial innovations to provide poor individuals with neglected tropical diseases.3,4 Infections can last for Neglected Tropical Diseases, Liverpool School of Tropical essential drugs. decades and cause severe disability and disfi gurement, Medicine, Liverpool, UK 13 parasitic (helminthic and protozoan) and bacterial with profound economic, social, and political con- (Prof D H Molyneux PhD) tropical infections, and dengue are the highest-burden sequences.3,11,12 The core group of 13 neglected tropical Correspondence to: neglected tropical diseases; another 20 include fungal, diseases results in roughly 57 million disability-adjusted Prof Peter J Hotez, George viral, and ectoparasitic infections (panel 2).3,4 Seven life years lost, which are greater than those for malaria Washington University, 4 Microbiology, Immunology and diseases are noteworthy because of their high prevalence and tuberculosis. More than 90% of this disease burden Tropical Medicine, 2300 Eye and amenability to control. These are the soil-transmitted results from the seven major diseases.4 Three features of Street NW, Ross Hall room 736, helminth infections (hookworm, ascariasis, and these diseases have brought them to international Washington, DC 20037, USA trichuriasis); lymphatic fi lariasis; schistosomiasis; and attention: they lead to poverty; low-cost and highly [email protected] dis eases that cause blindness—trachoma and oncho- cost-eff ective control approaches might eliminate some cerciasis (river blindness; table 1). About 600–800 million of the diseases and create universal access to essential people, mostly children, have the soil-transmitted medicines; and control of these diseases would have helminth infections.3 Of these, hookworm infection, simultaneous and sustainable eff ects on poverty which causes childhood and maternal anaemia, results reduction. in the greatest disability, and is the highest-burden The economic eff ects of disease control have been neglected tropical disease.3,4 Among 200 million people shown around the world since the early with schistosomiasis, adolescents and young adults 20th century. 13 Investment in disease control could rescue (15–25 years) have the highest infection intensities, as the people in the bottom billion through its eff ect on measured by numbers of eggs in stool or urine, and the four key elements of the poverty trap: health (especially most severe adverse eff ects—anaemia, wasting, and maternal and child), agriculture, education, and pain.9 Another 120 million people have lymphatic infrastructure.2 Several major neglected tropical diseases adversely Panel 1: Poverty-promoting features of neglected aff ect a family’s economic potential through their tropical diseases debilitating eff ect on the health of children. The soil-transmitted helminth infections and schistosomiasis Reduced child survival impair children’s growth, development, and physical Hookworm infection; ascariasis; trichuriasis; schistosomiasis fi tness.3,4 Hookworm infection and schistosomiasis also Costs of treatments and seeking inappropriate or reduce child survival by causing severe anaemia during ineff ective health care pregnancy, which leads to low birthweight and increased 14 Leishmaniasis; lymphatic fi lariasis; onchocerciasis; human infant and maternal mortality. In Africa, anaemia African trypanosomiasis caused by hookworm infection can exacerbate the clinical course of falciparum malaria, especially in Reduced agricultural productivity children and women.15 For diseases, such as leish- Lymphatic fi lariasis; onchocerciasis; trachoma; hookworm maniasis, the treatment can easily cost a family’s income infection; schistosomiasis; dracunculiasis for the year and lead to sale of assets (eg, land and 16 Educational eff ects livestock). Hookworm infection; trichuriasis; ascariasis; schistosomiasis; Because they arise mainly in rural areas where families onchocerciasis depend on subsistence agriculture, the neglected tropical diseases impair agricultural productivity. 1570 www.thelancet.com Vol 373 May 2, 2009 Viewpoint deworming programmes have shown that intervention Panel 2: Neglected tropical diseases against neglected tropical diseases in childhood is a highly For more on neglected tropical diseases 21,25 see Helminth infections cost-eff ective approach to improvement of education. http://www.plosntds.org and Ascariasis;* trichuriasis;* hookworm infection;* An investment of US$3·50 per child on disease control http://www.globalnetwork.org 25 strongyloidiasis; toxocariasis and larva migrans; lymphatic could result in the gain of an extra school year. fi lariasis;* onchocerciasis;* loiasis; dracunculiasis;* Because these diseases prevent the achievement of the 3 schistosomiasis;* food-borne trematodiases; taeniasis fi rst six Millennium Development Goals, their control cysticercosis; echinococcosis with low-cost and cost-eff ective interventions could start long-term economic growth and development. Reduction Protozoan infections of disease burden or interference with transmission of Leishmaniasis;* Chagas disease;* human African neglected tropical diseases through population-based trypanosomiasis;* amoebiasis; giardiasis; balantidiasis chemotherapy was introduced in the 1920s. Examples of Bacterial infections success since then include mass drug administration Bartonellosis; bovine tuberculosis; buruli ulcer;* leprosy;* with diethylcarbamazine, and selective treatment or leptospirosis; relapsing fever; rheumatic fever; trachoma;* administration of diethylcarbamazine-medicated salt to 26 treponematoses interrupt the transmission of lymphatic fi lariasis. Similarly, vector control followed by mass treatment with Viral infections ivermectin led to the control of onchocerciasis in ten Dengue fever; yellow fever; Japanese encephalitis; rabies; west African countries,20 whereas azithromycin treatment haemorrhagic fevers and the SAFE (surgery, antibiotics, face cleanliness, and Fungal infections environmental improvement) strategy have eliminated Mycetoma; paracoccidiomycosis trachoma that causes blindness in Morocco, Oman, and Iran, as reported to WHO,27 and multidrug treatment Ectoparasitic infections has eliminated leprosy as a public health problem in Scabies; myiasis; tungiasis more than 93 countries.28 The effi cacy of mass treatment *13 core neglected tropical diseases. was confi rmed in a systematic review of randomised controlled trials.29 Because the major multinational pharmaceutical companies provide many of the drugs Agricultural activity is reduced directly from impaired used for mass treatment free of charge (whereas other worker productivity and hence reduced harvests, or drugs are available as low-cost generics), this approach is indirectly by reduction of food security when farmers one of the most cost-eff ective global public health control are forced to fl ee fertile areas because of high rates of measures.3 Mass drug administration for neglected endemic diseases. The seven main diseases have a tropical diseases also provides some of the highest rates particularly devastating eff ect on agricultural labour. of economic return in any public health programmes, Workers with lymphatic fi lariasis and chronic, often from 15–30%, and addresses fundamental irreversible lymphoedema of the lower limbs, and human-rights issues.3,11,28,30 Public–private partnerships hydrocele have substantially reduced agricultural working with WHO, the World Bank, and other UN productivity or, in some cases, they are forced to stop agencies are providing mass drug administration to working altogether.12,17 Similarly, blindness, resulting millions of people every year, leading to control and, in from trachoma or onchocerciasis,18,19 and anaemia, some cases, elimination of neglected tropical diseases.3,31 which might arise in adults because of hook worm In sub-Saharan Africa, the network of more than disease