Man dies from brain-eating amoeba linked to potted soil

While the symptoms associated with acanthamoeba castellanii can be scary, experts say it's not a major risk for those without compromised immune systems.
Close up of a man using a trowel to plant a small cucumber plant
An 82-year-old man in Georgia contracted a rare amoeba while gardening.Sherry Galey / Getty Images

A man in Georgia died at 82 after being infected by an amoeba that is presumed to have grown in soil, according to a case study published by researchers at Emory University.

According to the case study, an autopsy found "liquefactive necrosis" in the brain, which research published by the National Center for Biotechnology Information defines as "characterized by partial or complete dissolution of dead tissue and transformation into a liquid, viscous mass," which happens in just hours.

The amoeba, which was identified of the acanthamoeba species, is similar to Naegleria fowleri, another type of amoeba which is usually transmitted through water in lakes and ponds. The acanthamoeba castellanii is most commonly transmitted through soil, dust and some bodies of water, according to Dr. Ishan Mehta, one of the study authors and an assistant professor at Emory University School of Medicine in Atlanta.

In this situation, it appears that the man contracted the amoeba while taking care of a potted plant. Mehta said that because the amoeba is so rare, there isn't a lot of data about what kind of soil or environment it tends to thrive in.

The amoeba can be contracted through the respiratory system or by getting into the bloodstream.

"In order to develop the neurologic manifestation, it has to be either you breathe it in or you have direct skin contact so it essentially gets into your skin and then through the bloodstream passes into the neurologic system," Mehta said.

While the amoeba may sound alarming, researchers said that many people will contract it and never have symptoms.

"We do find it in patents that have no symptoms whatsoever," said Mehta. "It can be in the nasal passages and not actually do anything. ... What we have seen with this particular amoeba is that it affects patients that have a very compromised immune system."

While the man who died did have a history of lymphoma, Mehta said that the patient had been in remission for 10 years and had not had any treatments or chemotherapy during that time period. Only 11 other cases exist where a non-immunocompromised person died from exposure to acanthamoeba castellanii, according to Mehta.

In those rare cases or in situations where someone is severely immunocompromised, the amoeba will cause neurological problems and other symptoms in the brain. According to the case study, the man died nine days after he began showing symptoms.

"This type of amoeba can cause primarily neurologic symptoms, that's what our patient had, where he was just more confused over time, had pretty bad headaches, and then as time progressed he developed seizures and then essentially had a neurologic abnormality," Mehta said.

Mehta repeated several times that the general population is not really at risk for severe harm from the amoeba.

"It's such a rare organism, and anyone can be a host for it, but it doesn't infect everybody," Mehta said, adding that there is no need to worry that "any potting soil you buy at the planting store could have" acanthamoeba castellanii.

"This is not something we need to be freaked out about," he said.