Are worms vital to human health?

"Could the humble worm hold the key to wiping out allergies and a whole lot of disorders of the immune system? Researchers in Nottingham are investigating whether giving hook worms to asthma sufferers can cure their condition. Another group in the US is trying a pig worm on patients with ulcerative colitis or inflammation of the colon and bowel. And scientists in Cambridge have proved that giving an extract of the tropical worm which causes billharsia to mice can stop them developing type 1 diabetes" - BBC