REGULAR doses of worms might rid people of inflammatory bowel disease, say
researchers in Iowa. They believe this distressing condition, which is
increasingly common in the developed world, is caused by the absence of
intestinal parasites. 鈥淲e鈥檙e living in sterile boxes, breathing sterile air and
drinking sterile water,鈥� says Joel Weinstock, who led the research.
Weinstock and his colleagues at the University of Iowa have already fed six
sufferers eggs that hatched and developed into parasitic worms. The results were
so dramatic that they are planning a larger trial this autumn. 鈥淏etween the
second and third week after treatment, five of the six patients went into
complete remission,鈥� says Weinstock. A single dose of worms eased symptoms for
about a month.
Inflammatory bowel disease鈥攁n umbrella term for ulcerative colitis and
Crohn鈥檚 disease鈥攁ppears to be caused by an overactive immune system.
Symptoms include diarrhoea, abdominal pain, bowel obstruction and bleeding.
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Weinstock noticed that the rise in inflammatory bowel disease was preceded by
a decline in intestinal worm infections. Seventy years ago, he says, 40 per cent
of American children had worms such as Ascaris lumbricoides, which grow
up to 20 centimetres long. As recently as the 1940s, many were infected with
smaller whipworms (Trichuris trichuria). 鈥淏y the 1960s, kids no longer
had it,鈥� says Weinstock.
鈥淭he worms living in the gastrointestinal tract have been with us for 3
million years or longer,鈥� he says. 鈥淥ur immune systems have grown used to their
presence.鈥� And without such parasites, Weinstock believes the immune system is
more likely to produce powerful inflammatory agents such as gamma-interferon,
which fire up the activity of white blood cells called macrophages. 鈥淎s we鈥檝e
de-wormed, people have developed immune systems which are not damped,鈥� he
says.
The six patients in the initial trial were chosen because steroids and other
drugs designed to dampen down the immune system had not helped. Working with his
colleagues David Elliott and Robert Summers, Weinstock gave each patient a drink
containing microscopic eggs of a species of intestinal worm that doesn鈥檛
normally infect people. Although these worms can survive in the human gut,
growing to about 1 centimetre, they cannot reproduce and are eliminated after a
couple of months.
Balfour Sartor, an expert on inflammatory bowel disease at the University of
North Carolina in Chapel Hill, is intrigued by Weinstock鈥檚 experiment. 鈥淚t鈥檚 an
appealing way of using something that鈥檚 of fairly low toxicity to treat a set of
diseases that for now we don鈥檛 have a cure for,鈥� he says. Sartor is himself
experimenting with Lactobacillusand Bifidobacterium gut
bacteria, again with the idea that they may have dampening effects on the immune
system.
However, there is still a long way to go before doses of worms or bacteria
emerge as an accepted treatment for inflammatory bowel disease. Larger
controlled trials are needed to show that the results obtained so far aren鈥檛
merely due to the placebo effect.
