Put parasitic worms on yourself

In 2004, David Pritchard himself covered his arm with a cloth covered with hookworm larvae, like maggots on the surface of meat. He kept the covering for a few days to make sure that those zigzag-shaped freeloaders would infiltrate his body.

He said: 'It is impossible to describe the itch when they penetrate your skin. My wife was quite worried about this issue. '

Dr. Pritchard, an immunologist at Nottingham University, is not a madman. That act was merely his scientific passion.

When he went to Papua New Guinea in the late 1980s, he found that Papu people (Australian aborigines) were infected with Necator americanus hookworms, parasites that live in the human intestines, and suffer from less related diseases. Autoimmune diseases include hay fever and asthma. For many years, Dr. Pritchard developed a theory to explain this phenomenon.

He said: 'The allergic reaction has been developed to eliminate parasites, and we think that worms have found a way to neutralize the immune system in an effort to find a way to survive. That's why people with hookworms have fewer allergy symptoms. '

To test his theory and find out if he could transform this phenomenon into a cure, Dr. Pritchard recruited experimental treatment participants ready to receive 10 hookworms. They can hope to eliminate allergy and asthma symptoms.

Since no one was involved in his experimental treatment, Dr. Pritchard used himself as an experimental subject to obtain approval from the National Health Department's internal rules committee.

In tropical regions, usually every year, hookworms are the cause of death of 65,000 people and cause hundreds of thousands of people with anemia. However, Dr. Pritchard said in controlled experiments with a small number of adults, this type of worm has never caused any problems.

His passion for immunology about parasitic infection began in 1977. Attracted by anecdotal reports from third world countries that parasites cause symptoms to disappear. Allergy, he completed his doctoral thesis at Birmingham University on the subject.

Later, he became an allergist to a pharmaceutical company, but the work made him bored, he returned to the academy world in Nottingham in 1981, studying how parasitic worms disable the system. rodent immunity.

He said: 'At that time, I noticed that this work must eventually be done on people. So I started looking for suitable tropical regions for research '.

In the late 1980s, the Wellcome Trust approved funding, and Dr. Pritchard and his Nottingham team went to Karkar Island, Papua New Guinea.

He recalled: 'We do not speak the native language, and are very poorly equipped. But we have built good relationships with people there. We gave them worm medicine and asked them, in compensated English, to concentrate their feces in a bucket for us. '

Hookworm larvae.(Photo: Hazel Thompson)

Hookworm infiltrates the victim's body when the larvae hatch from the eggs in the stool of an infected person, passing through the skin, usually through the soles of the feet. From there they blend into the bloodstream in the body, go to the heart and lungs, and then get swallowed into the intestines when they reach the throat. They mature in the small intestine, where they live for many years by clinging to the intestinal wall and sucking blood. After screening stool samples to remove hookworms destroyed by worm medication, the team came to a very interesting conclusion: The villagers have high levels of allergy-related antibodies in their blood. most have the smallest and smallest parasitic worms, which suggests that these antibodies produce a certain level of protection against parasitic worms.

Hookworms seem to be equipped to resist. After they developed in the digestive system, the host often interpreted an abnormal immune response, which led Dr. Pritchard to suspect that worms reduced the body's protective effect, causing the environment of they become easier.

He emphasized: 'Living in the forest for a long time gives you time to think. Since then I have the idea that moderate levels of worms can be beneficial in certain cases. '

He began to consider this possibility. Suppose he can concentrate people with allergies, put worms in their bodies and see if symptoms like wheezing or teary eyes disappear?

Nearly 20 years later, his dreamy idea blossoms. After Dr. Pritchard's self-infecting experiments, the National Health Commission's Commission allowed him to conduct a study with 30 volunteers in 2006, 15 of whom received 10 hookworms. . Tests showed that after six weeks, T cells of people infected with worms began to produce chemical concentrations associated with less inflammatory reactions. This suggests that their immune system is more inhibited than 15 recipients. Although becoming a host with a small number of parasites, recipients of worms only feel a bit inconvenient.

Participants were very satisfied with the disappearance of allergy symptoms. People with chronic allergies start making online comments about research, a Yahoo group of 'worm therapy' appears.

Dr Pritchard said: 'Many people who are given the drug have asked to switch to worms, and many people infected with worms have chosen to keep them.'

He currently recruits patients for large-scale experimental therapy, hoping to announce the results next year.

Some allergic patients are anxious to try the measure. The executive of the Yahoo group, Jasper Lawrence, a Silicon Valley businessman, established a clinic in Mexico, which provided this treatment (once a worm was put in the body for $ 3900).

Dr. Pritchard said he understood the motive of those unregulated efforts. He said: 'The incident is also worrying. Obviously there are many patients who desire to be cured, and they consider it a perfect method. '

Dr. Pritchard was the first scientist to insert hookworms into patients under experimental conditions, but he was not the first to conclude that parasite infection can alleviate allergy symptoms. Previous studies also have a certain support for his ideas.

In 2000, Maria Yazdanbakhsh, an immunologist at Leiden University in the Netherlands, studied 520 Gabonese children and found that children with Schistosoma haematobium, a parasite that causes schistosomiasis, have The fewer allergic reactions to pollen, this is one of the most common types of environmental allergies.

Dr. Prichard and Carstern Flohr, another Nottingham scientist, returned to Southeast Asia in 2006 to continue the study of Dr. Yazdanbakhsh with a survey of 1,600 children in rural Vietnam. They achieved results that matched studies in Papua New Guinea and Gabon.

Subjects with higher levels of infection have less allergic reactions to pollen than uninfected children. Although reports of parasites reinforcing allergy resistance have been introduced for many years, only in 2005 did Rick Maizels, a biologist at the University of Edinburgh discover an explanation. reasonable biology.

When Dr. Maizels and colleagues introduced Heligmosomoides polygyrus, a round worm similar to hookworms in humans, into mice. They discovered that mice for some unknown reason created more T. control cells.

Dr. Maizels said that T cells regulate the resistance response by secreting interleukin-10, a compound that counteracts the stimulating effects that immune system cells produce in an allergic reaction.

He said: 'There is a lot of evidence that allergy is the over-reaction of the immune system. Worms only adjust for it to decrease. '

Based on the results of his research, Dr. Maizels said Pritchard's work is very promising. He said: 'I think it is very likely that hookworms have a similar effect on the immune system in humans.'

Some scientists argue that Dr. Pritchard is balancing on moral strings, because putting parasites into the patient's body can affect their health. Peter Hotez, microbiologist at George Washington University, who is developing hookworm vaccine, said parasites are one of the first causes of inhibition of growth and malnutrition in developing countries. .

Dr Hotez said: 'If a child is infected with 25 hookworms, it will lose the amount of iron needed daily, and because this worm reduces the ability of the immune system, they can increase risk of diseases such as AIDS or malaria in the host. So in the current situation, I think this therapy is too dangerous. '

But he still supports Dr. Pritchard's work from the basic aspect of the idea: 'The question is whether you can isolate the worm's molecule used to neutralize the immune system and use it. they are for treatment purposes'.

Because of the potential side effects, Dr. Pritchard never imagined that thousands of patients would line up in clinics to get parasites and flu vaccinations.

He said: 'The worst scenario is the damage that may occur. I worry about intentional infection, but at the same time feel that my hypothesis should be carefully checked. '

His long-term goal is to find out exactly how worms reduce the immune system's surveillance, so he can find ways to develop anti-allergy and immune-suppressing drugs.

He said: 'We are studying the molecular mechanism that this worm uses, and hope that it is possible to find a molecule that distracts the immune response from allergies.'

A new drug that mimics the effect of hookworms on the immune system is also capable of curing Crohn's disease, arthritis and other autoimmune conditions.

Despite the hope that he could eventually eliminate the hookworm completely from his allergy treatment, Dr. Pritchard still fears the potential danger that no parasite researcher has ever experienced. .

He recounted: 'I brought myself into my body 50 worms, then had stomach pain and diarrhea. But with 10 children, we determined the dose did not produce those symptoms. The patients are very satisfied. They kept the worms, every day I received e-mails from people who wanted to get worms all over the world. '