Commentary
Neglected Tropical Diseases
Challenges, Progress, and Hope
Rapid-impact packages, which combine antimicrobials, can successfully treat these diseases. But funding their distribution is a long-term challenge.
By Ann M. Campagna, M.D., Mrinal M. Patnaik, M.D., and Patricia F. Walker, M.D.
In September of 2000, the United Nations adopted eight goals aimed at combating and eliminating extreme poverty, hunger, and disease in all countries by 2015. One of those goals is to “combat HIV/AIDS, malaria, and other diseases.”1 These “other diseases,” referred to as neglected tropical diseases (NTDs), are lesser-known, but equally devastating in terms of morbidity and mortality. They include 13 chronic disabling diseases that affect a disproportionate percentage of the world’s poorest citizens (Table).
These diseases have affected humanity for centuries. They promote poverty because they are associated with physical disfigurement and significant social stigma. The seven most prevalent diseases—roundworm, whipworm, hookworm, schistosomiasis, elephantiasis, trachoma, and river blindness—primarily affect people in rural parts of some of the most impoverished regions of the world.2 In addition to chronic morbidity, these diseases cause more than 534,000 deaths annually and are responsible for the loss of 57 million disability-adjusted life years.3
Clinical trials have shown that multiple drugs are effective in reducing transmission and prevalence of the 13 diseases. Diseases such as kala-azar (old-world visceral leishmaniasis), Chagas’ disease, African sleeping sickness, guinea worm, and buruli ulcers, which are found in specific geographical regions of the world, require fairly toxic parenteral forms of treatment. The seven most prevalent neglected tropical diseases have a broader distribution and are amenable to therapy with oral agents that often can be given in single doses.
The treatments for these diseases are highly effective; however, there are no commercial markets for the antibiotics that target them.1 In fact, only 1% of new drugs brought to market between 1975 and 1999 (13 of 1,393) targeted tropical diseases. Between 2000 and 2004, only four drugs entered the market—three for malaria and one for leishmaniasis. This abandonment of research into and development of treatments for these tropical diseases is often attributed to the developing countries’ lack of purchasing power and the consolidation of pharmaceutical companies and their emphasis on serving the most profitable segments of the market.
Several public-private partnerships including the African Programme for Onchocerciasis Control and the Global Alliance to Eliminate Lymphatic Filariasis have been working independently to control specific NTDs. The Global Network for Neglected Tropical Disease Control is a relatively new organization that works with these public-private partnerships and others to bring integrated drug treatment for these diseases to parts of the world that need them most. The goal is to provide communities with a specific group of antibiotics, collectively called rapid-
impact packages (RIPs), that can treat and prevent the spread of the seven most common NTDs.
Rapid-impact packages consist of four groups of antimicrobials (albendazole or mebendazole, ivermectin, Praziquantel, and azithromycin). When used in combination, they can successfully treat the most prevalent NTDs. Three of the five most commonly used antibiotics have been donated by pharmaceutical companies, while the remaining two have been made available at a greatly reduced cost. It has been estimated that this package of four antibiotics can be distributed for approximately $0.50 per person. It has been further suggested that these packages could be administered at the same time as vaccinations and vitamin supplementation. An additional benefit of the RIPs is that they are also effective for treating scabies, strongyloidosis, pediculosis, tungiasis, and cutaneous larva migrans.3
Challenges associated with using RIPs include patient compliance, the emergence of anthelmintic drug resistance, reinfection following treatment, and long-term sustainability of distribution through community-directed programs.3 In addition to monitoring success of the RIP distribution program, which has already been implemented in seven African countries, it has been suggested that the cost of ongoing surveillance be rolled into the cost of the drug packages and their distribution. Assuming the goals of reducing disease burden and interrupting disease transmission are achieved, we may need to develop more sophisticated means for detecting these diseases as they become less prevalent.
Although pharmaceutical companies are donating most of the medications for the RIPs, the cost of the two drugs that must be purchased—Praziquantel and albendazole—will add up over time. The Global Network for Neglected Tropical Disease Control has established the PUSH (Poverty reducing, Uplifting communities, Simple solutions, Hope for all) fund to pay for these medications. The total cost of the entire initiative is estimated to be between $1 billion and $2 billion. The U.S. Agency for International Development, Geneva Global, and the Bill and Melinda Gates Foundation have each contributed to the fund. However, their donations only cover a fraction of the total cost.
Thousands of African refugees now call Minnesota home, and it is important for the physicians who care for them to be aware of the diseases they may bring from their countries of origin and how to treat them. In our ever-expanding global village, it also is our responsibility to be aware of the challenges faced by developing nations and to recognize the fact that we can make a difference in the health and lives of the people who live in those countries.
Albert B. Sabin once said, “A scientist who is also a human being cannot rest while knowledge which might reduce suffering rests on the shelves.” We do live in a hope-filled world. The resources to combat these debilitating diseases are here today, ready to be used. We would like to see more physicians support efforts to eradicate neglected tropical diseases and eliminate the deaths and suffering that go along with them. MM
Ann Campagna and Mrinal Patnaik are residents in the University of Minnesota’s department of internal medicine. Patricia Walker is a professor of medicine at the University of Minnesota.
References
1. United Nations Millennium Declaration, 55th session. Agenda item 60 (b). 18 September 2000.
2. Molyneux DH, Hotez PJ, Fenwick A. “Rapid-impact interventions”: How a policy of integrated control of Africa’s neglected tropical diseases could benefit the poor. PloS Med. 2005;2(11):e336.
3. Hotez PJ, Molyneux DH, Fenwick A, Ottesen E, Ehrlich Sachs S, Sachs JD. Incorporating a rapid-impact package for neglected tropical diseases with programs for HIV/AIDS, tuberculosis, and malaria. PloS Med. 2006;3(5):e102.