Can hookworms cure allergies?

Source: Web exclusive, July 2010

What would you rather have: a chronic health condition for which there is no cure, or the chance to rub a batch of parasitic worms into your skin? It may sound nutty and, well, disgusting. Nonetheless, many people are enthusiastically opting for the latter.

‘Helminthic therapy’ (taken from the word ‘helminth,’ for parasitic worm) is an upwardly trendy, somewhat controversial but undoubtedly provocative suite of treatments involving small doses of the eggs and larvae of parasitic worms to treat a range of common and incurable conditions.

The idea: to correct improperly functioning immune systems.

The target: chronic auto-immune-related illnesses, including hay fever and other allergies, asthma, eczema, and irritable bowel disorders such as Crohn’s disease, colitis and even’according to some of its proponents’multiple sclerosis.

Helminthic therapy stems from the ‘hygiene hypothesis,’ a theory that dates back to a seminal research paper published in 1989 in the British Medical Journal, which attempted  to explain the puzzlingly high incidence of autoimmune disorders in Western nations.

For example, almost 10 percent of Canadians age 12 and over have asthma today, according to the Asthma Society of Canada. That’s up from just 2.3 per cent in 1979 (in adults age 15 and over), and the prevalence continues to rise worldwide by about 50 percent every decade.

What could explain the increase? According to the hygiene hypothesis, we are too clean. This is a problem because not all bugs are ‘bad.’ In fact, some are indispensable’we would not be able to digest food or even live without many of the microbes found in our stomachs.

According to this theory, children’s immune systems fail to learn how to deal with foreign bugs properly without regular exposure to ‘normal’ levels of germs.

People in many tropical nations, where parasites are widespread, suffer lower rates of conditions that involve over-active immune responses such as asthma and allergies. Parasites evolved to dampen the immune system’s ability to fight them’so, the theory goes, if an immune system is overreacting, a small dose of parasites might just be what the doctor ordered.

Except that your doctor will not make such an order. It is not legal to prescribe parasitic worms in Canada. Health Canada has not yet approved any ‘medicinal maggots,’ which they classify as drugs, so it could be some time before such therapies are routinely available. Any Canadian eager to try them out now ‘should speak to their doctor about clinical trials,’ Health Canada said via email.

However, it is legal to order parasitic worms online from a handful of private suppliers. One of the most popular is the web-based company, Autoimmune Therapies.

Jasper Lawrence, who co-founded Autoimmune Therapies three years ago with chemist Marc Dellerba, says he decided to provide parasitic therapies after he managed to control his own ailments with hookworms.

After suffering from severe allergies and asthma for most of his life, Lawrence says he ‘gave up on modern medicine.’ He was inspired to try a dose of parasites after learning about immunologists experimenting with hookworms in Britain.

Unable to find any source of hookworm larvae in the U.S., ‘even on the Internet, where you can find all manner of weird things,’ he decided to go to an area in Cameroon where he says a fifth of the population plays host to the worms. His method of contraction? ‘I simply walked barefoot through the latrine areas.’

His allergies and asthma vanished months later, and he decided to offer the therapy to people in more palatable forms: sticky patches of whipworm larvae and whipworm eggs suspended in saline. He says he offers the chance of a five-year remission of symptoms (on average), whereas conventional therapies only offer the possibility of a lifetime on antihistamines, inhalers and other medications.

The treatment doesn’t come cheap: $2,900 US for a single dose of hookworm or whipworm, or $3,900 US for a combination of the two. According to Lawrence, the treatment typically works within two or three months, though he says that on rare occasions, patients have had to wait up to 11 months. So far, 180 people in total have received helminthic therapy through the Autoimmune Therapies website.

Is there a valid scientific basis for this?

‘There is a growing perspective that a lack of ‘external’ allergenic or pathogenic attacks on developing immune systems leads to immune systems that do not function properly, and there is a well-known link between parasitic helminth infections and allergic responses,’ says Professor Dan Brooks, a parasitologist with the University of Toronto, who studies parasites such as worms and how they affect their mammalian hosts. ‘But the crux of the matter, I believe, is what can we do ethically and morally to stimulate young and naive immune systems without violating the first line of the Hippocratic Oath: Do no harm.’

Lawrence insists that the treatment is low-risk: the doses are too small to result in a full-blown parasitic illness, the eggs and worms will not reproduce in your body (or be transmitted to anyone else), and if at any point you feel unwell (or just find the idea of deliberately infecting yourself with worms intolerable), you can easily rid yourself of them with a routine dose of anti-parasitic medication.

‘Between 25 and 30 percent of people who encounter this idea have a strong negative reaction, regardless of their education’it’s clearly because of the ‘yuck factor” but what is the harm in trying this, especially when conventional medicine has nothing else to offer in the way of a cure?’ he says.

Many academics agree that the therapy is not without some risks. Some researchers and clinicians are concerned that in some cases, a dose of worms could actually weaken the immune system. The Autoimmune Therapies website states that ‘people who are HIV positive or have some other serious chronic and incurable infection will be refused treatment.’

Nonetheless, many researchers say the idea is worth a closer look.

‘Helminthic therapies do seem to work, but unfortunately most of the evidence is just anecdotal,‘ says Professor Derek McKay, a physiologist at the University of Calgary. ‘It’s still just a hypothesis’not a theory.’

The low rates of autoimmune diseases in tropical, developing countries with high levels of parasitic infections could just be a coincidence. Other factors could be at play and much more research needs to be done, he says.

‘But in the meantime, I think there is a place for helminthic therapy as an option for people for whom steroids and anti-inflammatories have failed,’ he says.

As fringe as it may seem, these parasites may have much to teach researchers about how to recreate the effects of helminthic therapies in drug form.