Worm infections point researchers toward inflammation therapies

Parasitic worms that infect billions of people may help researchers design new treatments for inflammatory disease, according to a Yale School of Medicine review. The same immune-dampening tactics that let the worms persist in the body can also blunt responses to vaccines, cancer and other infections, the review said.

Neima Briggs, an instructor of medicine in infectious diseases at Yale School of Medicine, examined how helminths shape the immune system in a review published in Clinical & Translational Immunology. Yale said the work focuses on infections caused by helminths, a category that includes tapeworms, flukes and roundworms.

About one in four people worldwide has a helminth infection, according to research cited by Yale. The worms range widely in size, from about 1 millimeter to 15 meters, and spread most often in places with poor sanitation through fecal-oral contact, Yale said.

Depending on the species, helminths can infect the intestines, gastrointestinal tract, lungs or other internal organs, according to the review. Yale said the infections can injure tissue, but often do so in a way the host can tolerate without developing a specific disease.

How worms quiet the immune system

The review said helminths can live in a host for years because they reduce immune activity enough to prevent strong protective responses. Briggs described the worms as highly successful regulators of immunity, saying their high infection rate and relatively low host mortality make them a compelling subject for immunologists.

According to the review, helminths alter the body’s type 2 immune response, which is activated when protective tissues are damaged and inflammatory signals known as alarmins are released. Because the worms need to remain inside the host, they suppress parts of this parasite-fighting response and push the immune system toward a more controlled state, Yale said.

Briggs calls that process “trained tolerance,” according to Yale. The idea is that in settings where people are repeatedly exposed to worms, tolerating a limited infection may cause less damage than mounting a strong inflammatory reaction each time.

That immune control is medically important for two reasons, the review said. It can leave people less able to respond to vaccines and other health threats, while also pointing to immune pathways that could be used to calm harmful inflammation.

Vaccine, cancer and autoimmune questions

Briggs is studying ways to improve vaccine performance in people who have, or previously had, helminth infections, Yale said. According to Briggs, weaker vaccine responses are especially evident with live vaccines, including measles vaccine and the BCG vaccine used against tuberculosis, where both response strength and durability are reduced.

The review also raised questions about helminths and cancer. Briggs said three helminths are classified as human carcinogens, and the review suggests they may affect cancer development by causing ongoing tissue injury, disrupting repair processes and changing immune defenses against tumors. Yale said more research is needed to define how helminths affect cancer risk and progression.

In autoimmune diseases, the review pointed to a different possibility. Yale said research in conditions such as Crohn’s disease and type 1 diabetes suggests helminths may reduce some inflammation and slow disease progression, prompting efforts to turn those effects into safe therapies.

The Briggs Lab is working to identify how helminths induce trained tolerance and whether those mechanisms can be adapted for inflammatory conditions, according to Yale. Briggs said the parasites may offer lessons that help advance human health, even as their infections remain a major global burden.

This story draws on original reporting from Medical Xpress.