HOUSTON. The World Health Organization (WHO) estimates that less than 10% of the $56 billion spent worldwide each year on health research is directed toward diseases that afflict 90% of the world's population. According to U.S. Senator John Kerry, "Market disincentives, especially the lack of a viable, cash-rich market, play against investment into these vaccines." In addition, many drugs effective against tropical diseases are no longer available or in danger of being pulled from the market because they are unprofitable, say researchers from the Baylor College of Medicine and Centers for Disease Control and Prevention (CDC). "Parasites are a very common causes of disease in the world but because there is no market for antiparasitic drugs, drug companies are discontinuing production," says Clinton White of the Baylor College of Medicine in Houston. This is because parasitic diseases are most commonly found in developing countries without funds to effectively support production of these drugs.