14 March 2024

Nasal rinsing with running water has been thought to cause unusual infections

US researchers have found 10 cases of infection with free-living amoebae from sinus rinsing. Tap water was a likely source of infection.

Free-living amoebae (Acanthamoeba) are found all over the world - in soil, lake, river and running water. These protozoa cause diseases ranging from keratitis (inflammation of the cornea) and granulomatous amebic encephalitis to central nervous system infections and rhinosinusitis.

Amoebas enter the human body through several routes - through the eyes (such as contact lenses), lesions on the skin, and the respiratory tract. And at risk are people who have had organ or stem cell transplants, cancer, HIV or diabetes - in other words, those with weakened immune systems. Amoebic infections are rare, but if you do get one, you have an 82% chance of dying.

Because of the ubiquity of amoebas, it is difficult to track down the specific source of this infection, much less develop ways to prevent it. One of the methods of preventing infection with protozoa is considered to be washing the nose - with the help of a special bottle, irrigator or neti pot. In any case, you need to use water, and as a recent study showed, two-thirds of U.S. adults consider tap water safe.

The authors of the new paper, published in the journal Emerging Infectious Diseases, reported 10 cases of infection with free-living amoebas. They were detected in Americans through nasal rinses between 1994 and 2022. Medics analyzed the clinical characteristics of the disease in each case and found that nine patients were diagnosed with rhinosinusitis and seven had chronic sinusitis. Also, all 10 were immunocompromised.

Seven patients reported that they had rinsed their noses to relieve sinusitis symptoms, two for ritual ablution. Four took only tap water, while one person took sterile water but dipped the rinsing device in running water.

As noted by the authors of the article, in theory you can get infected with amoeba in any rinse, but the risk increases with constant contact with tap water. The researchers also emphasized that the new work does not identify the exact source of the infection. Nevertheless, they recommended rinsing the nose with boiled, sterile or distilled water.

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