A popular public beach on an Iowa lake was forced to close over the weekend after a visitor from Missouri was infected with a rare brain-eating amoeba.

Last Friday, Lake of Three Fires State Park in Taylor County was closed to swimmers after the Missouri resident became ill from a rare brain infection caused by the amoeba Naegleria fowleri. The swimmer had recently visited the beach before being hospitalized and placed in the intensive care unit.

According to the Iowa Department of Public Health, the beach was closed as a “temporary precaution” as federal and state authorities are investigating the danger presented by the amoeba and the extent of its presence at the lake. Missouri officials said that the ongoing investigation may go beyond the lake as a source of infection to determine its origin.

"It’s strongly believed by public health experts that the lake is a likely source, but we are not limiting the investigation to that source because it hasn’t been confirmed. Additional public water sources in Missouri are being tested," Missouri's public health department said.

Naegleria fowleri is a microscopic single-celled free-living ameba that can cause a rare life-threatening infection of the brain called primary amebic meningoencephalitis (PAM). Once infected, PAM can cause a person to experience nausea, vomiting, fever, or headache and, if left untreated, hallucinations, seizures and confusion. However, it is not considered to be contagious.

According to the Centers for Disease Control and Prevention, the fatality rate is over 97% for those who become infected with the single-celled living organism.

Last August, a 7-year-old boy from Tehama County, California, died after being infected with Naegleria after swimming in a local lake. A month later in September, a child in North Texas died after contracting the rare brain-eating amoeba at a city splash pad.

People who believe they may be experiencing symptoms associated with a Naegleria fowleri infection after swimming in freshwater are advised to seek medical attention immediately.