Helminths refer to small parasitic animals that infect humans and are transmitted through contaminated soil. There are three types of soil-transmitted helminths:

Around the world at any given time, about 807 to 1,121 million people are infected with Ascaris, 576 to 740 million people are infected with hookworm, and 604 to 795 million people are infected with whipworm, according to the Centers for Disease Control and Prevention.

These infections were once common in the United States and other developed countries. However, they are much less widespread today due to improvements in hygiene, sanitation, and living conditions. Now they are almost exclusively found in developing countries.

Helminths are passed from animals to humans through contact with infected feces. The ways that this may happen include:

  • drinking water that has been infected
  • walking barefoot on contaminated soil
  • not washing hands after handling pets or using the bathroom
  • eating fruits and vegetables that have not been carefully cooked, washed, or peeled

Once inside the body, helminths thrive inside the small intestines. Symptoms may cause:

  • blood loss
  • diarrhea
  • abdominal pain
  • nutritional deficiencies

Infections can be cleared up with prescription medication.

A helminthic infection may seem like something to try to avoid. However, some people purposely infect themselves to manage the symptoms of chronic illness. This is called helminthic therapy.

Helminthic therapy involves intentionally being infected with helminths, like hookworms or whipworms. This therapy is used to treat:

Helminths are thought to help treat these diseases by inhibiting the body’s immune response, which in turn reduces inflammation.

To begin the treatment, you will receive an injection of the worm’s eggs or drink several doses of a liquid containing the worm’s eggs. Your doctor will monitor your condition closely so that you don’t get sick over the course of treatment.

Over time, the worms may cause dangerous side effects. These include increased risk for anemia. A protein deficiency may also develop, leading to difficulty in the ability to think, and stunting physical growth in some patients.

Medications are available to offset these side effects. People undergoing helminthic therapy may also be prescribed iron supplements for anemia.

There is evidence from studies in mice and rats that helminth infections are able to inhibit the immune response. A 2017 review of three studies concluded the treatment is both safe and effective.

A 2017 study tested how whipworm affected 252 people with Crohn’s disease. The study showed that dosing study subjects over 12 weeks was safe, but there was no clinical difference in remission rates between the people who received the whipworm and the people who received the placebo.

Additional research is needed to determine to clearly establish the safety and effectiveness of this treatment.

One major problem for people looking for helminthic treatment is that they will often have to travel outside of the United States to be infected with the worms.

Currently, only one clinic in Tijuana, Mexico, is providing hookworm treatment for Crohn’s disease. However, as more research is done, there may be an increase in the availability of helminthic therapy.

It is unsafe to treat yourself by ordering hookworm or other helminth eggs over the Internet. You should only undergo helminthic therapy under the supervision of a doctor. There are many potential side effects.

The U.S. Food and Drug Administration (FDA) hasn’t approved helminth therapy. The FDA has granted Investigational New Drug status to several species of worms, including pig whipworm (Trichuris suis) and human hookworm (Necator americanus).

This means that U.S. researchers are allowed to test the worms in humans. There has been a special interest in the pig whipworm because it can’t live inside the human gut for very long. This might make it a safer option for humans.