The Bill and Melinda Gates Foundation recently committed $34 million to help fight what are called neglected tropical diseases. These parasitic diseases plague the world's poorest people who frequently live in remote areas without clean running water. The diseases are called "neglected" because they are often given less priority than diseases with high mortality rates.
The World Health Organization reports that about one billion people are affected by Neglected Tropical Diseases.
Guinea worm, river blindness, hookworm, schistosomiasis, trachoma, lymphatic filariasis and sleeping sickness are some of the diseases in this group.
They are spread by insects and contaminated water and soil.
From 1975 to 1999, according to the WHO, less than one percent of the 1300 new drugs on the market were targeted for treatment of NTDs , or Neglected Tropical Diseases.
Dr. Peter Hotez of the Global Network for Neglected Tropical Diseases says getting money for treatment was difficult until the Gates Foundation addressed the need.
"So it is a real hurdle to get drugs, vaccines, diagnostics for these NTDs [Neglected Tropical Diseases] developed. All I can say is thank God for the Bill and Melinda Gates Foundation that has stepped up, come through and led the way in terms of research and development," Dr. Hotez said.
Dr. Hotez says the $34 million from the Gates Foundation will help treat seven of the most common Neglected Tropical Diseases at an average cost of 50 cents a year per person. The cost of treatment is kept down, he says, because five of the needed drugs will be donated for free or at low cost by pharmaceutical companies.
The near eradication of the guinea worm is perhaps the greatest success story among the group of Neglected Tropical Diseases.
Guinea worm disease has existed since the beginning of civilization. Mummies like this one, exhumed centuries after burial, have shown traces of Guinea worms.
In modern times, guinea worms are more commonly found in people who live in rural areas without adequate sanitation.
Craig Withers is an expert on guinea worm disease with the Carter Center in Atlanta, Georgia. "The people who have this disease are in the most remote, rural, poorest areas of the world," he said. "They live in unhygienic environments."
Guinea worm disease occurs when stagnant water used for drinking and bathing is contaminated by the worm's larvae.
When a person comes into contact with the infected water, he or she ingests the larvae which then mature and mate. The female worm grows and then breaks through the human skin.
Craig Withers says the cycle continues when the infected person seeks relief from pain by going into the water. "People go to that water to cool off the sensation, and as soon as you touch the water, the eggs are emitted into the water," he explained.
Two decades ago, guinea worm infestation was at its peak in 20 countries in Asia and Africa. Three and a half million people were infected.
Then, in 1998, former U.S. President Jimmy Carter visited Ghana and saw how guinea worm disease made life miserable for the villagers. He organized a coalition of international health agencies in endemic countries to fan out and teach local people how to eradicate the disease.
Withers says now, before villagers drink from stagnant water, they are taught to use a simple filter or cloth to block the larva.
Today, only about 5,000 cases of guinea worm disease still exist, primarily in southern Sudan.