Science unravels tapeworm DNA

Scientists said Wednesday they had unravelled the genetic code of the tapeworm, unearthing data that should lead to more efficient drugs against the dangerous intestinal parasite. Tapeworms are among the first known parasites of humans, recorded by Hippocrates and Aristotle as long ago as 300 BC. Published in the journal Nature, the research highlighted genetic similarities between tapeworms and cancer tumours. The finding suggests existing cancer drugs that suppress cell division and prevent DNA replication point to a novel cure, which would save time and money in development, the authors said. "These genome sequences are helping us to immediately identify new targets for much-needed drug treatment," Matthew Berriman of the Wellcome Trust Sanger Institute said in a statement. People contract tapeworms by ingesting their eggs or larvae, found in raw or undercooked meat of an infected animal or freshwater fish, contaminated water or through close contact with an infected person or livestock. Areas of poor sanitation pose the highest risk. Some larvae settle in the human intestine and become adult worms of up to three metres (10 feet) long. The infestation can be easily treated with two standard drugs. But the larvae can also migrate to other body parts, where they continue to develop and are harder to spot and treat. Larvae cysts in the eyes can cause blindness, while cysts in the brain are a major cause of epilepsy in the developing world and are potentially life-threatening. "Tapeworm infections are prevalent across the world and their devastating burden is comparable to that of multiple sclerosis or malignant melanoma (skin cancer)," said Berriman. The tapeworm is specially adapted to parasitism, it has no gut, head or light-sensing organs, but has a unique surface able to withstand its host's digestive acids while still absorbing nutrients. Berriman and a team of researchers mapped the genomes of four types of tapeworm and discovered they all lacked the ability to synthesise fatty acids and cholesterol that are crucial for larvae development -- instead scavenging these from the host. An effective treatment could thus be to target the genes and proteins involved in the scavenging process, they wrote. The team also discovered why drugs that target enzymes in the central nervous system of other flat worms had not been effective: tapeworms produce few of these vital proteins. "Our data will serve as a 'parts list' for tapeworm scientists to explore and identify vulnerabilities over a much, much shorter timeframe," Berriman told AFP. "The study identifies some of the vulnerabilities already, such as parts of metabolism that the parasite is highly dependent on."