Troubled by asthma? Hay fever? Obesity? Koichiro Fujita has a cure: Swallow a tapeworm. Off and on over the past 5 years, Fujita, a professor of environmental parasitology at Tokyo Medical and Dental University, has hosted tapeworms in his gut. He believes they not only have helped keep him slim but have cleared up his hay fever. He currently houses three. "Hosting the worms has been very beneficial," he says.
Fujita says parasites, particularly roundworms, were endemic among the Japanese until the government's postwar eradication programs. But just as parasites declined, asthma and other allergic conditions proportionally increased. Up to 40% of Japanese children now suffer from atopic dermatitis, a chronic skin condition unknown a generation ago. Fujita suspects that the Japanese fetish with cleanliness, which has led to heavy use of household disinfectants and antibacterial soaps, may be aggravating the problem by giving immune systems so few challenges that they overreact to allergens. Tapeworm secretions and excretions can spur the production of antibodies that block such responses, Fujita believes. He claims that a substance his team isolated from tapeworm secretions cleared up atopic dermatitis in mice (the study hasn't been published). Fujita says he has convinced his wife and a few postdocs to join him in hosting tapeworms, even though colleagues look down on the research and the university has forbidden human experiments.
Naohiro Watanabe, an immunologist and parasitologist at Jikei University School of Medicine, Tokyo, won't comment on Fujita's exercise. He says studies of patients with roundworms indicated they had heightened allergic responses. But for tapeworms, he admits, "we just don't have any scientific data."
