Deadly amoeba brain infection can result from unsafe nasal rinsing, CDC warns

The Centers for Disease Control and Prevention (CDC) has issued a new report that highlights a potential danger of nasal rinsing with unsterile tap water: amoeba infections of the skin, eyes, lungs or brain. 

In the report, published Tuesday (March 12) in the journal Emerging Infectious Diseases, the agency detailed the cases of 10 U.S. patients who were infected with a type of amoeba called Acanthamoeba between 1994 and 2022. Nine of the cases occurred in the past decade. All of the patients had rinsed out their nasal passages, most with devices like squeeze bottles or neti pots, before falling ill. They did so for various reasons, including to relieve symptoms of chronic sinusitis, or sinus iNFLaMMAtion. 

The patients experienced a range of health complications as a result of their amoeba infections. Six people developed skin diseases, and six experienced a rare nervous system infection called granulomatous amoebic encephalitis (GAE), which affects the brain and spinal cord. Of the 10 people who were infected, seven survived their illnesses and three of the people with GAE died.

All of the infected patients had weakened immune systems, most commonly because they had cancer and were undergoing treatment. Of the five people who reported what kind of water they had used for nasal rinsing, four said they used tap water and one said they'd used sterile water but also submerged their device in tap water. 

Related: 'Brain-eating' amoebas are a new concern in northern US states, health officials advise

Tap water typically contains small amounts of microbes that are usually killed by the acid in the stomach. However, these microorganisms can survive in the nose and cause infections if they end up in there. Nasal rinsing with unsterile tap water has previously been linked to a variety of amoeba infections, such as those caused by the brain-eating amoebas Naegleria fowleri and Balamuthia mandrillaris.

Acanthamoeba amoebas can also cause a life-threatening, brain-damaging disease, that being GAE, which starts with symptoms of confusion, headaches and seizures. The amoebas are found worldwide and live in both soil and bodies of water, including in lakes, rivers and tap water.