Every year, up to 50 million people contract an infection that often seems like a mild stomach bug.
Most recover with only diarrhea. But for up to 100,000 people, the outcome is fatal.
The culprit is a single-celled parasite known as Entamoeba histolytica. It enters through contaminated food or water, particularly in areas with poor sanitation.
Once inside the body, it chews ulcers into the colon, melts parts of the liver, and can eventually reach the lungs and brain.
For decades, scientists were baffled by how this parasite could do so much damage while avoiding the body’s natural defenses.
A parasite in disguise
After more than 20 years of research, a team led by microbiologist Katherine Ralston from UC Davis has cracked the code.
The parasite survives by dressing itself in pieces of human cells.
Ralston’s studies revealed that E. histolytica rips apart human cells and steals surface proteins from them.
It then places these molecules on its own membrane, essentially cloaking itself in human tissue.
This disguise allows it to evade the immune system’s detection – especially from key components called complement proteins that would normally attack it.
In 2014, Ralston published early findings on how the parasite damages cells by biting chunks off them – a process called trogocytosis.
But it wasn’t until 2022 that she and her team connected these attacks to the parasite’s ability to camouflage itself.
A turning point in the fight
Even though the parasite is highly complex – its genome is far larger than those of HIV or salmonella – scientists have found a way forward.
By combining RNA interference (RNAi) with CRISPR gene-editing technology, researchers can now tag and alter specific parasite genes.
With this method, they can pinpoint the genes and proteins responsible for E. histolytica’s survival strategy.
The goal is to develop drugs or vaccines that disable the parasite’s disguise and stop its destruction.
This article is based on information from Popular Science.