A soil bacterium protein used to kill insects on organic crops has been shown to be a highly effective treatment for intestinal parasitic roundworms. These parasites, which include hookworms and whipworms, infect about two billion people in underdeveloped tropical regions and are cumulatively one of the leading causes of debilitation worldwide. Scientists report that a crystal protein known as Cry5B produced by Bt (Bacillus thuringiensis) is highly effective at a single dose at curing mammals of intestinal roundworm infections.
The researchers showed that Bt crystal proteins, used as insecticides for over five decades and known to be non-toxic to vertebrates, kill roundworms. Parasitic roundworms are considered by public-health officials to have a combined debilitating impact on human populations that is comparable to, or in some estimates greater than, that of malaria or tuberculosis. Intestinal roundworm diseases are among the most important causes of disease burden in school-aged children worldwide, leading to stunted growth, retarded cognitive and mental development and malnutrition. Children with these parasites are more likely to be trapped in poverty because they cannot physically work or think their way out of their condition. The parasites also have a significant burden on pregnant women and working adults.
Despite the large impact of these parasites on the developing world, few drugs have been developed to effectively combat their infection in human populations. Only one drug, albendazole, is now widely used in administering single-dose treatments to large populations. But because of the enormous numbers of people that need to be treated repeatedly, the development of resistance to albendazole is a serious threat and is already suspected in three studies in Sri Lanka, Ethiopia and Uganda. Furthermore, albendazole is a far from ideal drug, having poor impact on whipworms and less than ideal incomplete impact on hookworms. The latest drug to be developed is tribendimidine, which clinically has similar efficacy as albendazole. But the Bt Cry5B protein is three times better than tribendimidine. Comparisons from the literature with the other anti-worm drugs against this same mouse parasite, Heligmosomoides bakeri, indicate that Cry5B is anywhere from 4 times to 10,000 times more effective than various other anti-worm drugs. Most of the Cry5B is degraded in the stomach, so if the protein can be protected from stomach degradation, it is likely to be an even more powerful drug against parasites. These results pave the way to developing Cry5B as a safe and superior drug against roundworms that can rid a terrible class of parasites from hundreds of millions of children and adults around the world.
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