Everything You Need to Know About Helminth Therapy

Helminth therapy is an experimental treatment involving intentional infection with live parasitic worms called helminths. These parasites have evolved to protect themselves by altering their host's immune responses.

Researchers are studying these intestinal worms as possible treatments for many conditions involving inflammation. These include COVID-19 and long COVID, autoimmune diseases, allergic conditions (such as eczema), asthma, and autism spectrum disorders.

This article looks at the types of helminths being investigated, plus the potential uses, benefits, risks, and effectiveness of helminth therapy.

3D illustration shows a cross-section of an intestine with helminths inside it.

tussik13 / Getty Images

What Does "Experimental" Mean?

An experimental treatment is one that has been through basic laboratory testing and approval by the Food and Drug Administration (FDA) to be tested in humans. Experimental treatments are not yet available from your healthcare provider.

Types of Helminths

Helminth therapy involves any of three types of worms that infect humans. They’re most common in moist, warm climates and unsanitary conditions. Typically, they’re spread through contaminated soil. The three types of helminths are roundworms, flatworms, and thorny-headed worms.

Helminth infection is rare in the United States. Around the world, though, about 24% of the population is infected at any given time.

Roundworms (Nematodes) 

Common types of roundworms (nematodes) are whipworms and hookworms. Their bodies are shaped like cylinders, similar to earthworms.

Roundworms cause the most human infections worldwide. They most often infect the intestines but can also be in your blood, lymphatic system, or internal tissues.

Flatworms (Platyhelminthes)

Two common types of flatworms (platyhelminthes) are flukes and tapeworms. As their name suggests, they have flat bodies. Their leaf-shaped head has a sucker that allows them to attach themselves to humans.

Flatworms typically infect the liver, blood, or bile ducts (tubes connecting the liver and small intestine).

Thorny-Headed Worms (Acanthocephalans)

Thorny-headed worms (acanthocephalans) have round bodies and barbs on their heads. They’re related to both tapeworms and roundworms.

They commonly infect animals, but human infection is rare. They live in the gastrointestinal (digestive) tract.

How Treatment Is Given

In current helminth therapy, a healthcare provider gives you an injection or a drink that contains helminth eggs. The unpleasantness of this practice may be too much for some people to handle, however.

Researchers are studying ways to develop medications based on helminth secretions or lab-created versions of them that would be easier to stomach and provide a safer, more consistent therapeutic amount.

Medications could also make it possible to deliver medicine directly to the site of the inflammation, even when the worms themselves can’t survive there.

Uses

Parasites sometimes change your body in ways that help them survive. Helminths give off substances that can alter or suppress your immune system, so it’s harder for you to fight these substances off. That’s similar to how immunosuppressant medications work.

Chronic (long-term) inflammation is a common factor in these conditions. Acute (short-term) inflammation is created and maintained directly by the immune system in response to damage or perceived threats. Its purpose is to get more oxygen and nutrients to the site so you can heal.

When inflammation becomes chronic, it stops being helpful and causes pain and other symptoms. That’s when inflammation needs to be treated.

COVID-19 and Long COVID

The SARS-CoV-2 virus that leads to COVID-19 causes inflammation in your immune system.

Symptoms of severe COVID-19 infection include trouble breathing, persistent pain or pressure in the chest, confusion, inability to wake up or stay awake, and in light-skinned people, pale, gray, or blue-appearing lips, skin, or nails.

Some researchers have hypothesized that specific helminths may help combat the systemic inflammation of coronaviruses responsible for much of the respiratory effects.

Autoimmune Diseases

In autoimmune diseases, the immune system mistakes a healthy cell, substance, or tissue in your body for a foreign invader. Researchers have identified more than 100 different autoimmune diseases, each with its own target or targets.

Immunosuppressant drugs are a common treatment for autoimmune diseases. Early research suggests helminth therapy may also be effective. A review of research details several helminth secretions that alter immune function. It also suggests helminth treatment was effective in animal models of common autoimmune diseases, including lupus, colitis, and arthritis.

Another review cites several human trials suggesting helminths are effective treatments for:

Some researchers have even speculated that helminths may contain the key to curing autoimmune disease.

Allergies

When you’re allergic to something, your immune system overreacts to a typically harmless substance it believes to be a pathogen. The runny nose, watering eyes, sneezing, and other symptoms are designed to flush unwanted substances out of your system.

Common allergens are:

Research suggests allergic diseases are increasing globally as parasitic-infection rates go down. Some scientists suspect that’s because the parasites have historically helped prevent the development of allergies.

One review notes inconsistent results in human studies of allergies. Still, researchers say there’s enough solid evidence to keep looking into helminth therapy.

Eczema (Atopic Dermatitis)

Eczema (dermatitis) involves inflammation in the skin. The most common type, atopic dermatitis, is caused by allergies.

Studies on helminth infection and eczema have been inconsistent. Some have shown that the parasites offer some protection against atopic dermatitis. Others have shown they make eczema more likely to occur. The difference may lie in the specific type of helminth that caused the infection. More research is needed.

Asthma

Asthma is a chronic, inflammatory condition that involves swelling of the airways, excess mucus, wheezing, coughing, and shortness of breath.

Asthma comes in several forms, but allergic asthma is the most common. A review of research shows promising evidence of helminth-derived asthma treatments. As with eczema, it may be that some helminth types increase the likelihood of asthma, while others decrease it or have no effect. Again, more research is needed.

Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a developmental disability that comes from differences in the brain.

Research suggests ASD involves inflammation in the brain (neuroinflammation) and abnormalities in the brain’s dedicated immune system. One study hypothesizes that a specific type of helminth may be beneficial for treating ASD due to its ability to alter the immune system.

Benefits

The benefits of helminth therapy may include: 

  • Lowering inflammation and its associated symptoms (such as pain, impaired mobility, and allergy and asthma attacks)
  • Stopping and preventing damage from autoimmunity (including joint or organ damage)
  • Possibly a lower side effect risk than current medications
  • New options for people who can’t take current medications for their condition(s)

The actual value of these benefits will only be known with more research and increased use of helminth treatments.

Risks

Even natural treatments can have risks and side effects. Helminth therapy is no exception.

Researchers know that some types of helminths may worsen certain conditions, such as asthma. They need to figure out which ones help and which ones do harm.

Infection with a small number of worms often causes no symptoms. At higher levels, they may also trigger parasitic disease, with symptoms including:

  • Abdominal pain
  • Diarrhea
  • Blood loss
  • Rectal prolapse
  • Slow physical growth and cognitive development 

Side Effects

In studies, side effects have been uncommon. They include:

  • Fatigue
  • Skin rashes
  • Digestive problems

Anthelmintic drugs can help clear the worms out of their system in people with parasitic diseases or bothersome side effects.

Vaccine Interference

A concern about helminth therapy is that animal studies suggest an active helminth infection may interfere with some vaccines. Researchers looked at H1N1 (swine flu) vaccines in helminth infected and noninfected mice. The vaccine failed significantly more often in the infected mice.

It’s unknown whether the same would happen in humans or with other vaccines. However, it could be a potential limiting factor in who could get helminth therapy and when. For instance, it might not be wise to start it before you’re scheduled for a vaccine or booster.

Effectiveness

The jury is still out on how effective helminth therapy is for any condition. Early studies provide some statistics, but they’ll need to be replicated in more extensive studies before we know how accurate they are.

Insignificant Difference

In a Crohn’s disease study, helminth therapy at low and medium doses was less effective than a placebo (an intentionally ineffective treatment used to provide a control group in research studies). The largest amount was effective in just over 47% of participants, compared to about 43% in the placebo group—not a significant difference.

Summary

Helminths are parasitic worms that can dampen the human immune response. That means they may be an effective treatment for immune-related, inflammatory diseases. These include COVID-19, autoimmune diseases, allergic conditions, and autism spectrum disorder. Research is in its early stages, so little is known about the safety and effectiveness of any condition. This treatment is classified in the United States as experimental.

A Word From Verywell

If you’re living with an inflammatory disease, you may be frustrated that a potential treatment like helminth therapy isn’t available yet. Remember, though, that proven treatments for your condition have established safety profiles. Alternative therapies, such as heminth therapy, can be tempting to try, but just because they’re natural doesn’t mean they’re safe. Be sure to clear any alternative treatments with a healthcare provider before trying them.

Frequently Asked Questions

  • Is helminth therapy safe?

    Early research suggests helminth therapy may be safe for many conditions. However, it does come with risks, including parasitic disease and a potential risk of worsening some conditions. More research will need to be done before we understand how safe this treatment is.

  • What diseases can helminths treat?

    Helminths may be able to treat autoimmune, inflammatory, and allergic diseases plus autism spectrum disorder. Research is promising but still in its early stages. In the United States, helminth therapy is classified as experimental, meaning your healthcare provider can’t yet prescribe it.

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