Federal and state health officials on Wednesday confirmed the presence of a brain-eating amoeba in an Iowa lake after one swimmer was infected and later died. The lake will remain open as infections are rare, but officials will create signage that warns of the parasite. 

The amoeba, also known as Naegleria fowleri, was found in the Lake of Three Fires, which is located in Bedford, Iowa, according to a statement from the Iowa Department of Health and Human Services (HHS) and the Iowa Department of Natural Resources, in conjunction with the Centers for Disease Control and Prevention. 

“Naegleria fowleri is an amoeba that commonly occurs in warm freshwater such as lakes, rivers, ponds and canals,” Wednesday’s news release said. “In extremely rare cases, it can cause primary amebic meningoencephalitis (PAM), a brain infection that may result when water containing the amoeba rushes up the nose and reaches the brain.”

Earlier this month, according to state officials, a Missouri resident swam in the Iowa lake and contracted primary amebic meningoencephalitis, which led to his death. 

Only 31 cases of the amoeba have been reported in the United States between 2012 to 2021, HHS said in its news release. The low infection rate makes it hard to determine why certain people get infected, when “millions of others who used the same or similar waters across the U.S. during the same time period,” the agency said. 

Even though officials confirmed Naegleria fowleri was present at the Iowa lake, it will reopen on Thursday, the state said. No more testing of the water is planned, but officials will add signage that warns swimmers of the dangers of the parasite. The lake had been closed since July 8. 

“There is no rapid, standardized test to detect Naegleria fowleri in water, which is why HHS and DNR recommend that Iowans assume the parasite is present and limit the amount of water that goes up your nose to help reduce your risk of infection,” the news release read. “Swimmers are encouraged to be informed and take precautions.”