Helminth therapy, also known as helminthic therapy, is an experimental therapy in which people intentionally infect themselves with live helminth parasites. As helminths can alter a person’s immune response, some people believe that helminthic therapy may, one day, help doctors treat some autoimmune and allergic diseases.

Currently, doctors in the United States cannot prescribe helminth therapy as a treatment. However, researchers can test certain types of worms in humans to explore whether they have the potential to treat certain conditions.

This article looks at the theory behind helminth therapy and the diseases that it could potentially treat. It also discusses what the current scientific research has to say about the effectiveness and safety of helminth therapy.

a researcher is holding a glass jar in a laboratoryShare on Pinterest
Alex Potemkin/Getty Images

Helminth therapy is the deliberate introduction of helminth parasites to the body to help treat a health condition.

Helminths are a large group of worm-like parasites, which include:

As a 2018 article explains, helminths have evolved over millions of years alongside their hosts. This has made them incredibly good at suppressing and altering their hosts’ immune response.

A parasitic infection diminishes the body’s immediate immune response. However, in some cases, these changes to the immune system can benefit the host by reducing overall inflammation. This benefit is one reason why some scientists are interested in helminth therapy.

Interestingly, a 2015 study points out that helminth infections have decreased in high income countries, where inflammatory and autoimmune diseases are most common. Although this link does not establish cause and effect, it is certainly possible that helminth infections could help suppress the development of some inflammatory conditions.

The same 2015 study notes that scientists have become interested in treating three main kinds of disease with helminth therapy:

As allergic disorders and autoimmune diseases happen when a person’s immune system malfunctions, the immunosuppressant effects of certain helminths may help some people with these conditions.

Autism spectrum disorder

Scientists have discovered close connections between certain kinds of inflammation and autism spectrum disorder (ASD). Therefore, some researchers speculate that helminth therapy might, one day, help some people with ASD.

However, scientists call for more studies into this area of research to get a full understanding of its potential benefits.

Scientists do not yet know whether helminth therapy can be effective.

Although helminth infections do seem to have positive effects on inflammatory conditions, research suggests that these may only occur in people whose helminth infection predates their inflammatory condition.

In a 2018 review, researchers looked at several animal studies that explored the effects of helminths on inflammatory bowel disease — examples of which include Crohn’s disease and ulcerative colitis. Although many of these results were positive, the authors cannot know whether similar effects would occur in humans.

Research on humans remains inconclusive. A 2017 study looked at the effect of a species of helminth on adults with Crohn’s disease over 12 weeks. The researchers split the study participants into four groups. Three of these groups received different doses of helminth eggs, and the remaining group received a placebo.

Although those in the group that received the highest dose of helminth eggs were slightly more likely than those in the placebo group to go into remission, participants in the other two groups were less likely to do so. Moreover, laboratory tests showed that the levels of inflammation in all of these groups were the same.

More research is necessary to explore the health effects of helminth therapy further. However, current research does not show this method to be an effective treatment option.

It is uncertain whether scientists could develop a safe form of helminth therapy in the future. However, there is a lot of evidence that helminth infections can cause a variety of health problems and even be fatal.

The possible complications of helminth infections include:

If helminth therapy is to progress, scientists will need to weigh the alleged benefits of helminth therapy against the known issues. They will also need to understand how to reduce the risk of helminth-induced health problems.

Helminth therapy is an experimental therapy, and the Food and Drug Administration (FDA) has not approved it as a treatment. For this reason, doctors in the U.S. cannot prescribe helminth therapy as a treatment.

There have not been enough long-term studies on helminth therapy to confirm whether it is safe. Moreover, medical science has not yet determined how to perform helminth therapy in a controlled and principled manner.

However, the FDA has granted Investigational New Drug status to certain species of worms, including pig whipworm and human hookworm. This status means that researchers in the U.S. can test the worms in humans.

Learn how clinical trials work here.

Helminth therapy involves giving a person helminth parasites, such as hookworm, that will live in their body. This type of therapy may help treat certain health conditions, such as Crohn’s disease, allergies, and ASD. The helminth parasites may do this by triggering an immune response that can decrease inflammation in the body.

At this time, helminth therapy remains an experimental treatment option for autoimmune diseases. It is not FDA-approved.

Scientists will continue to research the potential health effects of helminths — both positive and negative.