A team at the University of East Anglia (UEA) has been investigating the secret behind the success of giardia, which has eluded scientists for more than 300 years.

They found that the parasite produces two main types of protein that enable it to cut through layers of protective mucus in the gut, breaking the links that knit cells together in order to easily access the nutrients within them.

The parasite, which people typically pick up through drinking infected water or contaminated food, causes a disease called giardiasis, with symptoms including diarrhea and stomach pains. Currently more than 200,000 people are ill with giardiasis and there are 500,000 new cases a year.

The research team, based in the National Institute for Health Research Health Protection Research Unit in Gastrointestinal Infections, at UEA’s Norwich Medical School, wanted to find out more about how the parasite’s activities can cause severe symptoms in some patients.

Working with colleagues at the Institute of Infection and Global Health at the University of Liverpool, the team looked at cell cultures infected with giardia in the laboratory to see what the parasite was producing that could be interacting with cells in the gut. Of the two “families” of protein identified, the team discovered that one “mimics” a group of human proteins called Tenascins.

Tenascin proteins are essential for us—they regulate cell adhesion during wound healing and tissue remodeling—providing help to cells to break apart when necessary and balancing the proteins that glue the cells together.

The giardia parasite has evolved by making proteins that are very similar to ours and able to trigger this process. However, the giardia tenascins are used instead to upset the body’s balance by preventing healing of the junctions between cells that hold them together.

The research is published in the journal GigaScience.