Researchers have found why some people are naturally protected from parasitic worms while others are not, according to new research.

British researchers have identified a protein that exists in some people's gut mucus that seems to be toxic to parasitic worms. Those with the protein are able to ward off infection, while those who lack the protein are more easily infected with the parasites, researchers said.

Parasitic worms are a major cause of death affecting up to 1 billion people, particularly in Third World countries, as well as domestic pets and livestock.

"These parasitic worms live in the gut, which is protected by a thick layer of mucus," study researcher Dr. David Thornton, of the University of Manchester's Wellcome Trust Centre for Cell Matrix Research, said in a statement. "The mucus barrier is not just slime, but a complex mixture of salts, water and large 'sugar-coated' proteins called mucins that give mucus its gel-like properties."

To study parasitic worm infection, researchers looked at the whipworm Trichuris muris, which infects mice (the human equivalent is Trichuris trichiura).

Researchers had previously learned that mice were able to expel the whipworm from their guts by making more mucus, which contains a protein called Muc5ac. This particular protein is rarely present in the gut , but when it is, it alters the physical properties of the mucus gel.

So, researchers wanted to see how Muc5ac impacted the ability of worms to infect the mice's bodies. They engineered some mice to lack the Muc5ac proteins, and found that the mice genetically incapable of producing the protein were unable to expel the worms, despite having a strong immune response against these parasites, researchers said.

Researchers realized that the Muc5ac protein is toxic to the worms and damages their health, according to the study.

Muc5ac is also essential for getting rid of other kinds of worms that cause problems in humans, including hookworm and the spiral threadworm, the study said. Together, these worms cause mortality and morbidity in up to 1 billion people around in the world, according to the study.

"For the first time, we have discovered that a single component of the mucus barrier, the Muc5ac mucin, is essential for worm expulsion," said study researcher Dr. Sumaira Hasnain, also of the Wellcome Trust Centre for Cell Matrix Research, in a statement. "Our research may help to identify who is and who isn't susceptible to parasitic worms, and it may eventually lead to new treatments for people with chronic worm infections."

The study was published today (May 5) Journal of Experimental Medicine.

Pass it on: Some people are able to ward off parasitic worm infection because they possess a certain protein in their gut mucus that is toxic to worms.

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