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Every year, 13 diseases that affect a fifth of the world’s population are responsible for the loss of 56.6 million disability-adjusted life years and 534,000 deaths. But because these diseases only afflict the world’s most impoverished and powerless people, the international community has forgotten about them.

Neglected tropical diseases (NTDs) are a group of parasitic worm and bacterial infections that together represent a huge disease burden. The seven most common NTDs are ascariasis, hookworm, trichuriasis, elephantiasis, river blindness, schistosomiasis, and trachoma. A 50 cent integrated package of rapid-impact medications has the ability to safely obliterate these seven diseases. Cheap therapeutics are available for other NTDs as well, but there is little funding for implementation.

Unlike HIV/AIDS, tuberculosis, and malaria, Neglected tropical diseases (NTDs) do not typically kill on their own, but they do lead to massive debility and poverty. Also unlike AIDS, NTDs lack a vocal afflicted but wealthy population to advocate for treatment. Many NTDs are ancient diseases that no longer threaten the developed world.

NTDs are largely neglected by the media and donors because they have a lower death percentage, said Dr. Edward T. Ryan, director of the Massachusetts General Hospital’s Tropical Medicine program.

“To a large extent, these are chronic diseases that disproportionately affect the most impoverished on the globe,” Ryan said. “They are often not on the radar screen of health funding agencies.”

Several NTDs also have the ability to either increase susceptibility to or worsen the course of the “big three” diseases — AIDS, tuberculosis, and malaria. For example, women with female genital schistosomiasis, a disease caused by the parasitic blood-fluke (schistosome) contracted by contact with contaminated freshwater, acquire problems ranging from infertility, to bladder cancer, to anemia and stunted growth in children. In addition, women also develop genital ulcers, and thus become much more vulnerable to sexually transmitted diseases, including HIV. A World Health Organization (WHO) working group concluded that there is a possible link between female genital schistosomiasis and HIV acquisition.

“This is one of the biggest underlying reasons for HIV” said Dr. Peter J. Hotez, president of the Sabin Vaccine Institute and a leading global health expert.

With as many as 45 million women infected with genital schistosomiasis, eradicating schistosomiasis has major implications for halting the spread of HIV as well.

A person with an NTD caused by a parasitic worm infection has a greater chance of contracting tuberculosis, and this chance increases with the number of infections. Co-infection of hookworm and malaria causes severe anemia in children and pregnant women, and this contributes to almost half of all deaths due to malaria.

According to Hotez, the international development community overlooks the chronic debilitating effects of NTDs and its impacts on the more famous “big three” diseases.

“The disease burden of NTDs is grossly underestimated,” Hotez said.

Historical neglect

In September of 2000, the United Nations articulated eight goals that would be the major focus of the global development community. The Millennium Development Goals (MDGs) called on the world to end extreme poverty, gender inequality, and solve other major problems that were hindering social and economic development in the world’s poorest countries. The UN General Assembly said that these goals should be achieved by 2015, four years from now.

MDG 6 was to “combat HIV/AIDS, malaria, and other diseases.” In the specific targets for this goal, the General Assembly acknowledged the many impacts of HIV/AIDS, malaria, and tuberculosis.

The importance placed on the Millennium Development Goals were such that MDG 6 was successful in promoting public sympathy for these three major diseases and billions of dollars in funding were raised. The Global Fund to fight AIDS, Tuberculosis, and Malaria raised $22 billion, the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) raised $32 billion, and the President’s Malaria Initiative (PMI) also committed $1 billion.

However, “other diseases” were neglected, and became known as neglected tropical diseases (NTDs). This glossing-over in the MDGs has complicated the work of tropical disease advocates.

“This was a huge problem,” Hotez said, “I mean, who wants to advocate for something called ‘other diseases’? You can’t really see Angelina Jolie doing that.”

Part of the confusion about “other diseases” stems from an inconsistent definition of NTDs. The Global Network, an advocacy organization dedicated to NTDs, cites 13 diseases caused by bacteria and parasites. On the other hand, the WHO’s NTD department covers 17 diseases. In academic papers, NTDs sometimes refer to a group of more than 30 diseases.

Hotez writes in the New England Journal of Medicine that a program to control NTDs would cost less than 10 percent of the programs for HIV/AIDS, tuberculosis, or malaria, and at the same time save the equivalent number of disability-adjusted life years. According to Hotez, the time has come for funding programs like PEPFAR, the Global Fund, and others to pay more attention to “other diseases.”

“We need to start integrating NTD control into the big funds” Hotez said.

“For relatively small investments,” Ryan added, “major scourges of humanity can be addressed. In terms of cost-effectiveness, a number of experts would say this is very cost effective for the global community.”