Close-up of a parasitic worm. Picture: ISTOCK
Close-up of a parasitic worm. Picture: ISTOCK

After 30 years of suffering, John Scott had given up on doctors and medicine — until he met the amazing Dr Wriggly.

Scott’s problems began when he developed allergic asthma as a child, which evolved into perennial rhinitis in his teens. By the time he was in his thirties, the Englishman’s food intolerance was so bad it threatened his survival.

Doctors discovered that he was suffering from Crohn’s disease. He tried everything modern medicine had to offer, Scott says, but nothing worked. Then, at a clinical trial at the University of Nottingham in the UK, he was introduced to Dr Wriggly: a hookworm a centimetre long and as thin as a hair that feasts on blood in humans’ small intestines.

"What he doesn’t know about the human immune system is clearly not worth knowing," Scott wrote about Dr Wriggly, the name he gave to his parasites. After infecting himself with the worms, he noticed after 12 weeks that his allergies had diminished.

A year-and-a-half later, Scott was eating normal foods for the first time in three decades. "It was simply amazing."

For most of the past century, Dr Wriggly and his friends were considered public enemy number one as science tried its best to eradicate them through mass deworming programmes. But now scientists are beginning to look at parasitic worms in a more favourable light.

Across the globe there is a growing underground movement using parasitic worms — or helminths — to treat auto-immune disorders such as Crohn’s disease, asthma and inflammatory bowel syndrome. It is known as helminthic therapy and the people who practise it often have to dodge law enforcement authorities to import the worms.

The parasites appear to have a magic switch that dials down overreactive immune systems.

"The theory is that the worm is a symbiotic organism that has evolved with us," explains Dr Katherine Smith of the division of immunology at the University of Cape Town.

"It doesn’t want to harm you, so it pretends it is not there by putting up a smokescreen."

This is known as the hygiene hypothesis and the idea is that a lack of exposure to parasites in early childhood — particularly in the first world — caused a rise in susceptibility to allergic illnesses such as asthma and hay fever in the 20th century.

"Hosting worms is something humans and our proto-ancestors have been doing for our entire time on the planet, with the exception of the last 50 years. The absence of worms is the abnormal condition that should be considered more carefully," says Garin Aglietti, who runs a website called, which offers helminthic therapy.

Smith is trying to understand what the worms are doing to immune systems at a molecular level. "Then we will see if it can be replicated with a drug." While tests on mice have shown clearer links between helminths and suppressing immune illness, human trials have been inconclusive. "It is harder with the human population, as we don’t have the controlled conditions, as with the mice," Smith says.

A possible side effect of helminthic therapy is what is known as worm flu, when the host experiences a period of fatigue and inflammation. Symptoms usually disappear after a couple of months.

"It has grown significantly over the last 10 years", says Aglietti, who became involved with helminthic therapy after he treated his psoriasis with hookworms from Belize.

"Certainly people are more aware and an increasing number of doctors seem to be adopting the therapy.

Some helminths are more harmful than others. The bilharzia fluke, which is known to suppress human immune systems, can cause serious liver and bladder damage

"When I first opened the clinic in 2007 maybe one in 10 doctors were aware or interested in our therapy — now we are probably closer to five in 10."

Critics of helminthic therapy point to the reason that medicine had launched mass worm-eradication programmes. Worms are known to affect nutritional intake and are linked to anaemia, weight loss and malnutrition. Studies also show that children infected with helminths are often too sick or tired to concentrate at school.

Some helminths are more harmful than others. The bilharzia fluke, which is known to suppress human immune systems, can cause serious liver and bladder damage.

"I think at the moment we don’t know enough; we still need to do fundamental research. Our ultimate goal is to move away from mice to humans," says Smith.

But helminthic therapy supporters point out that they use worm parasite species, such as the pig hookworm and whip worm, that have less harmful effects on the human body.

People who commit to helminthic therapy are in it for the long haul. It took Dr Wriggly four years to sort out most of Scott’s ailments. Today his Crohn’s disease is in remission and, even in the height of pollen season, he hardly gets a sniffle.

But to maintain this, he has to keep Dr Wriggly.

"Worm colonies need to be managed long term, but this concept is somewhat challenging for modern western humans, who’ve become accustomed to solving their health problems rapidly by popping a pill or two," explains Scott.

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