What the Hook?

Do you suffer from asthma, hay fever or some other allergic reaction? If so, how far would you go to get rid of your wheezing, incessant sneezing, itchy and watery eyed symptoms? Giving your allergies the boot has little to do with any drugs and more to do with Necator americanus – the hookworm. Research on hookworms in tropical soil has shown curative promise for autoimmune-related illnesses. Not convinced. Well there are enough believers in this non-FDA approved “helminthic therapy” since a Mexican clinic has been opened by entrepreneur Jasper Lawrence at a whopping cost of close to $4000 a pop per worm inoculation.

The basis for this new found therapy started in 2000 when immunologist Maria Yazdanbakhsh was studying over 500 Gabonese children infected with Schistosoma haematobium, one of a family of parasites that cause schistosomiasis, a parasitic infection uncommon in the United States. Those infected with the parasite had a lower immune response to dust mites which is one of the most common environmental allergens around. Four years later, Dr. David Pritchard took the idea of the hookworm’s allergy stopping abilities to the next level when he infected himself with 50 hookworms. The British scientist placed the pin-sized hookworms, which look like maggots on rotting meat, on his arm and covered it with a dressing. The itch as the worms penetrated Pritchard’s skin he explains only as “indescribable.”

Pritchard’s action was a follow-up to his earlier observations in Papua New Guinea during the late 1980s. He observed that Papuans infected with the hookworm, Necator americanus did not experience autoimmune-related illnesses such as hay fever and asthma. Pritchard developed a theory for his observation in New Guinea. He theorized that the parasites figured a way to switch off the body’s immune response which created an environment within the host that was suitable for its survival. Consequently, those infected with the hookworm had fewer allergic symptoms.

To get the National Health Services (NHS) ethics committee in Britain on board with his theory Pritchard tested himself. The quantity he inoculated himself with gave him stomach pain and diarrhea. But in 2006, armed with data from his Papuans study and the promise of using fewer worms to minimize the side effects, the NHS allowed him to conduct a small scale study using 30 test subjects. He infected 15 of the study’s participants with 10 worms each. Compared to the placebo group those who received worms not only showed little discomfort as hosts to a small amount of hookworms but they also experienced no allergic reactions.

The participants spread word about this new hookworm therapy and soon a Yahoo helminthic therapy group popped up. While the worm rave among allergy sufferers is growing many experts are concerned about the process of infecting patients with hookworms. Peter Hotez, a microbiologist at George Washington University is developing a hookworm vaccine. However, he worries that the hookworm therapy in the current form is too risky because infection carries the effects of stunted growth and malnutrition in developing countries. This allergy eradicating hookworm may be a welcomed therapy for some; however, in the tropics it kills. 65,000 people in tropical regions die each year and many more suffer from severe anemic conditions. Hotez and others recognize the important contribution hookworms can provide to help treat autoimmune-related diseases but think that direct infection carries too many potential risks for patients. Hotez stated, “The real question is could you isolate the molecules the worms are using to suppress the immune system and use them for therapeutic purposes?”

This is exactly what Pritchard envisions. He hopes to identify the mechanism hookworms use to turn down the immune response to allergens and provide an alternative to the current allergy drugs and immune-suppressant treatments available. Ultimately, developing a new drug class that can be offered to treat patients with other autoimmune diseases such as arthritis and Crohn’s disease minus the health risks associated with direct infection by hookworms.

Sources: http://www.nytimes.com/2008/07/01/health/research/01prof.html?ref=science