Progress against Neglected Tropical Diseases
April 2, 2011
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Significant progress towards the elimination and eradication of neglected tropical diseases has been made in the last decade. The development of public-private partnerships, drug donations from major pharmaceutical companies, increased country and international agency commitment and effective intervention strategies have led to dramatic declines in rates of infection from these debilitating diseases.
Over the last five years, neglected tropical diseases (NTDs)— a group of debilitating infectious diseases that contribute to extreme poverty—have been the focus of increased attention. Countries, supported by a variety of global initiatives, have made remarkable headway in combating NTDs—including diseases such as soil-transmitted helminths (intestinal worms), lymphatic filariasis (elephantiasis), onchocerciasis (river blindness), schistosomiasis (snail fever), and trachoma—and guinea worm may be the next disease eradicated from the planet.
The prospects for reducing the enormous burden caused by NTDs have changed dramatically in just the past few years, in part due to the growing recognition of the linkages between the fight against these debilitating diseases and progress towards the United Nations Millennium Development Goals (MDGs).
The remarkable efforts of public-private partnerships underthe leadership of the World Health Organization (WHO)— which include the pharmaceutical industry, academic and research institutions, donors, nongovernmental organizations, national governments and local communities—have revolutionized the treatment and control of many diseases. For example, when the Mectizan Donation Program was launched by Merck & Co. Inc. in 1987, collaboration between the public and private sectors in addressing global health challenges was uncommon. The program was initially established to oversee the donation of their drug Mectizan® (also known as ivermectin) “for as long as needed” to treat onchocerciasis, and was expanded to include lymphatic filariasis in 1998. Programs such as this one make it financially possible to provide the annual or biannual drug doses required for treatment of these diseases to the millions of people at risk.
Since then, pharmaceutical companies have donated billions of doses of drugs to programs such as the African Program for Onchocerciasis Control and the Onchocerciasis Elimination Program for the Americas (Merck & Co.), the Global Programme to Eliminate Lymphatic Filariasis (GlaxoSmithKline, Merck & Co.), the International Trachoma Initiative (Pfizer), Children Without Worms (Johnson & Johnson), and the WHO Program to Eliminate Sleeping Sickness (Bayer, Sanofi-aventis) to provide treatment for those NTDs. For schistosomiasis control, praziquantel has been provided via WHO by Merck KGaA and by MedPharm to the Schistosomiasis Control Initiative. Drugs for leprosy control are provided free by Novartis.
This collection of programs and alliances has been successful in bringing together partners to address NTDs, but there are others who also provide support to national programs fighting these diseases.
The Carter Center spearheads efforts with the Centers for Disease Control (CDC), WHO, and UNICEF to eradicate guinea worm disease. This disease has been eliminated in all but four countries, and cases have been reduced by more than 99 percent. The final battle to find and contain the last cases in the hardest-to-reach parts of the world is under way.
Bilateral development agencies also contribute, including the U.S. Agency for International Development (USAID) Neglected Tropical Disease Control Program, which was established in 2006 to reduce the burden of NTDs. USAID expanded efforts in 2008, launching the Neglected Tropical Diseases Initiative which committed $350 million (2009 to 2013) to deliver integrated NTD treatment to 300 million people in Africa, Asia, and Latin America. Furthermore, President Obama’s Global Health Initiative, announced in February 2010, also set ambitious goals for NTD treatment. One area the initiative hopes to address is the reduction of the prevalence of the seven most common NTDs by 50 percent among 70 percent of the affected population. Specific goals include the elimination of onchocerciasis in Latin America by 2016, and the elimination of lymphatic filariasis globally by 2017.
An improved understanding of the relationship between NTDs and extreme poverty has prompted other new initiatives. In addition to the MDGs, there are many international and regional goals which help spur action to improve health. For example, in 2001, WHO adopted a resolution to reduce parasitic worm infections by deworming 75 percent of all at-risk school-age children by 2010— the largest public health program ever attempted. WHO’s Global Plan to Combat NTDs has as its goal the prevention, control, elimination, or eradication of NTDs, particularly the elimination or eradication of a targeted group of diseases by 2015.2
Promoting even greater awareness and coordination is the Global Network for Neglected Tropical Diseases, an advocacy and resource mobilization initiative dedicated to raising the awareness, political will, and funding necessary to control and eliminate the seven most common NTDs, which launched in 2006.
innovation and Scientific advances
Development of innovative strategies for the delivery of existing drugs and methods to encourage behavior change have allowed for continued progress in controlling NTDs globally.
Significant efforts have been made to prevent trachoma using the SAFE Strategy, which was introduced by WHO in 1996. The strategy uses surgery to correct eyelid defects that lead to blindness, antibiotics to treat active infections, face washing, and environmental improvement (by providing clean water and sanitation) to prevent transmission of the bacteria that cause trachoma.4
New strategies for distributing drugs to infected populations have increased access to medications and created the possibility of controlling some diseases to the point of elimination:
• Distribution of drugs to an entire population, known as mass drug administration (MDA), has allowed countries to significantly control onchocerciasis, lymphatic filariasis, schistosomiasis, trachoma, and soil- transmitted worms.5 An integrated approach using a combination of four drugs can treat multiple diseases at once.6
• Community-directed treatment is a sustainable and cost-effective method of MDA, which was developed by African researchers for the distribution of ivermectin to treat onchocerciasis (river blindness). This strategy empowers communities to take responsibility for drug distribution and has delivered hundreds of millions of drug doses, as well as other health interventions, often to populations with little access to health services.7
• To assist in implementing interventions, researchers have developed rapid mapping techniques which allow for targeting of drug distribution
programs and facilitate planning for more integrated approaches. This enhances efficiency and reduces costs, particularly by identifying where the diseases overlap.
National research programs, WHO and other international agencies, and foundations are supporting research and development for “tool-deficient” diseases, where existing drugs are inappropriate or diagnostic and surveillance tools inadequate. Innovative nonprofit product development partnerships have also emerged to fill the gaps.
Programs to treat and control NTDs are some of the most cost-effective in public health, with remarkable rates of return from annual treatments with donated products or other interventions.8 As a result of dedicated partnerships and increased global efforts, millions of lives have been saved or improved by preventing disability and disfigurement.
Guinea worm disease is on the verge of being the second disease in human history (after smallpox) to be eradicated. One of the most remarkable global health success stories, it will be eradicated without the use of vaccines or drugs.9 In 1986, there were an estimated 3.5 million cases in 20 countries. Since then, cases have declined by 99.7 percent. In 2009, 3,109 cases were reported globally, with cases confined to four African countries.10, 11
The number of new leprosy cases per year has also fallen dramatically, and the disease remains a public health problem in only seven of the more than 100 countries where it used to be endemic. Since 1985, 14.5 million people have been cured.
Lymphatic filariasis (elephantiasis) has been successfully controlled or eliminated in China, Costa Rica, Egypt, South Korea, Solomon Islands, Sri Lanka, Suriname, Thailand, and Trinidad and Tobago.12, 13
Since 2000, the Global Program to Eliminate Lymphatic Filariasis has helped to deliver 1.9 billion treatments to individuals living in 48 of the 83 filariasis- endemic countries. In 2007 alone, over 546 million people were treated.
Onchocerciasis (river blindness) has been eliminated in Colombia, and studies at sites in Senegal and Mali have demonstrated that elimination using ivermectin alone is feasible in Africa as well.14, 15 A program launched in 1974 that used insecticides to kill infected black flies eliminated the disease as a public health problem in 10 West African countries, benefiting 60 million people. In other regions of Africa, drug treatment is used instead to control blindness and skin disease. Community-directed distribution of ivermectin reached more than 54 million people in 16 countries in 2007. It is estimated that by 2010, the sight of 800,000 people will have been saved.16
Prevalence and intensity of infection of schistosomiasis (snail fever) have been significantly reduced in Uganda, Burkina Faso, Mali, Niger, Tanzania, and Cambodia. Prevalence in Egypt has been reduced from around 20 percent to less than one to two percent over the past two decades. China has also made substantial progress, reducing cases from 11 million in 1950 to less than one million in early 2000.
Trachoma has been reduced from 149 million cases in 1997 to 60 million cases in 2008, thanks to the implementation of the SAFE strategy. Oman, Morocco, and Mexico have eliminated blinding trachoma using this strategy. Another 15 countries are making strides towards elimination.
While the prospects for reducing the burden caused by these diseases have changed dramatically, challenges still remain. With a comparatively modest, time-limited financial push, many of these diseases can be controlled or even eliminated.
integrate control and elimination efforts with other programs
Traditionally, partnerships and programs have been devoted to the control or elimination of a single neglected disease. However, people can be infected with more than one NTD simultaneously. Since the donated drugs are effective against several of these infections, major health gains, as well as administrative efficiencies, are achieved by coordinating efforts to address several diseases at once. One study estimated that, if programs were combined, drugs could be delivered at a cost savings of 26 to 47 percent.17
Further benefits could be gained by including NTD control efforts in malaria and HIV/AIDS programs. Investing in NTD control also promotes and improves the efficiency and coverage of immunizations, vitamin A and bed net distribution, and maternal child health programs.18, 19
invest in research and development for drugs, diagnostics, and surveillance tools
Although there have been advances in drug development, essential medicines to treat many NTDs are too expensive, highly toxic or becoming less effective. Investments are needed in many
trypanosomiasis (sleeping sickness), visceral leishmaniasis, Chagas disease, and Buruli ulcer need to be improved.
• In some worm diseases, a drug which kills adult worms would pave the way to more rapid elimination and could lead to eradication.
• Tools to quickly and inexpensively identify whether a disease has reentered a population need to be developed for programs in the elimination phase.
• Monitoring drug efficacy is essential because of the potential development of drug resistanc-especially given the huge scale of mass-treatment programs. New antihelminthic (anti- worm) drugs are needed to keep ahead of potential resistance and shorten the duration of interventions.6
increase global financing to control and eliminate NTDs
An estimated $2 to $3 billion will be needed over the next five years to control and eliminate NTDs.20 The funding gap for drugs alone is an estimated $222 million (from 2008 to 2012).3 Additional funds are needed to cover drug delivery costs, social mobilization, training, and monitoring and evaluation. U.S. funding is expected to increase, and the United Kingdom has committed £50 million over the next five years to fight NTDs.1 Overall, however, the funds committed represent only a fraction of what is needed for global control of the seven major diseases.3
1. USAID NTD Initiative, “About the NTD Initiative,” http://www.neglecteddiseases.gov/about/index .html (accessed September 20, 2009).
2. WHO, Global Plan to Combat Neglected Tropical Diseases 2008–2015, 2007, http://whqlibdoc .who.int/hq/2007/WHO_CDS_NTD_2007.3_eng .pdf (accessed September 18, 2009).
3. P. Hotez, et al., “Rescuing the Bottom Billion Through Control of Neglected Tropical Diseases,” Lancet 373 (2009): 1570–5.
4. S. Polak, et al., “Mapping the Global Distribution of Trachoma,” Bulletin of the World Health Organization 83 (2005): 913–919.
5. P. Hotez, et al., “Control of Neglected Tropical Diseases,” The New England Journal of Medicine 357 (2007): 1018–1027.
6. D.H. Molyneux, P. Hotez and A. Fenwick, “‘Rapid-Impact Interventions’: How a Policy of Integrated Control for Africa’s Neglected Tropical Diseases Could Benefit the Poor,” PLoS Medicine 2 (2005): e336.
7. WHO, “How Community-Directed Treatment with Ivermectin (CDTI) Began,” http://www.who .int/apoc/cdti/history/en/index.html (accessed September 18, 2009).
8. D.H. Molyneux, “‘Neglected’ Diseases but Unrecognised Successes—Challenges and Opportunities for Infectious Disease Control,” Lancet 364 (2004): 380–383.
9. C. Paddock, “Guinea Worm Eradication Almost Complete Says Jimmy Carter,” 2008, http://www .medicalnewstoday.com/articles/132147.php. (accessed September 15, 2009).
10. The Carter Center, “Guinea Worm Eradication Program,” 2009, http://www.cartercenter.org/ health/guinea_worm/index.html (accessed September 23, 2009).
11. WHO, “Monthly Report on Dracunculiasis Cases, January–April 2009,” Weekly Epidemiological Record 84 (2009): 212.
12. E.A. Ottesen, et al., “The Global Program to Eliminate Lymphatic Filariasis: Health Impact After 8 Years,” PLoS Neglected Tropical Diseases 2 (2008): e317.
13. M. Bockarie and D. H. Molyneux, “The End of Lymphatic Filariasis?” British Medical Journal 338 (2009): b1686.
14. The Carter Center, “Onchocerciasis Elimination Program of the Americas,” 2009, http://www .cartercenter.org/health/river_blindness/oepa. html (accessed September 24, 2009).
15. L. Diawara, et al., “Feasibility of Onchocerciasis Elimination with Ivermectin Treatment in Endemic Foci in Africa: First Evidence from Studies in Mali and Senegal,” PLoS Neglected Tropical Diseases 3 (2009): e497.
16. WHO, “African Program for Onchocerciasis Control (APOC): About Us,” http://www.who.int/ apoc/about/en/ (accessed September 22, 2009).
17. M.A. Brady, P.J. Hooper and E.A. Ottesen, “Projected Benefits from Integrating NTD Programs in Sub-Saharan Africa,” TRENDS in Parasitology 22 (2006): 285–291.
18. B.G. Blackburn, A. Eigege and H. Gotau, et al., “Successful Integration of Insecticide- Treated Bed Net Distribution with Mass Drug Administration in Central Nigeria,” American Journal of Tropical Medicine & Hygiene 75 (2006): 650–55.
19. Special Programme for Research and Training in Tropical Diseases, Community-Directed Interventions for Major Health Problems in Africa: A Multi-Country Study (Geneva: WHO, 2008).
20. White House Press Office, “Fact Sheet: Fighting Neglected Tropical Diseases Around the World,” Press Release, 2008.
21. D.H. Molyneux, “Elimination of Transmission of Lymphatic Filariasis in Egypt,” Lancet 367 (2006): 966–968.
22. R.M.R. Ramzy, et al., “Effect of Yearly Mass Drug Administration with Diethylcarbamazine and Albendazole on Bancroftian Filariais in Egypt: a Comprehensive Assessment,” Lancet 367 (2006): 992–99.
23. Global Alliance to Eliminate Lymphatic Filariasis,
The Global Elimination of Lymphatic Filariasis: The Story of Egypt (Geneva: WHO, 2003).
24. Global Alliance to Eliminate Lymphatic Filariasis, “10 Years of Progress Towards Elimination: Success in a Changing Policy Environment,” http://www. filariasis.org/documents/GAELF5reportEnglishWeb. pdf (accessed September 30, 2009).