CDC issues warning against nasal rinsing using tap water after 10 patients contracted deadly brain-eating amoeba

The CDC has issued a warning against using tap water for nasal irrigation after investigating a number of cases where the practice led to fatal brain infections.

Officials at the agency looked at 10 patients who contracted the deadly amoeba acanthamoeba — a single-celled organism that can spread to the brain and kill.

Three of these people died from the infection linked to their use of tap water in nasal irrigation tools such as neti pots. A further seven people suffered serious illness and were hospitalised.

The CDC, which examined patient records from 1994 to 2022, blamed unsanitary tap water for causing the problem.

Unhygienic tap water can reach the brain when it is flushed into the nose. Researchers used the findings to encourage people who rinse their noses to use boiled, sterile or distilled water.

For the latest study, ten patients ranging in age from 32 to 80 reported nasal irrigation prior to their Acanthamoeba diagnosis. Seven were men and three were women.

All of them were immunocompromised, a condition that puts them at increased risk of serious infection.

Nine patients were diagnosed with rhinosinusitis, or inflammation of the nasal cavity and sinuses, 6 had GAE, 6 had cutaneous disease, a type of skin infection, and three had osteomyelitis, an infection of the bones that can cause pain, swelling and limited mobility.

The fact that most infections involved the skin and sinuses probably contributed to the relatively high survival rate of the study population. Three people died, all of whom had GAE.

The survival rate for GAE is low – between seven and 10 per cent. It is also rare, with only a few reports disease every year.

Once introduced to the nasopharynx at the back of the nasal passages, the amoeba can travel directly to the brain into the bloodstream or directly into body tissue.

It triggers the immune system to general masses of immune cells called granulomas, which contribute to tissue destruction. Some of the symptoms of GAE include headache, fever, confusion, seizures, and focal neurological deficits, depending on the areas of the brain that are affected.

GAE caused by this particular amoeba is slow moving and a person can have it for weeks or even months before dying.

At least half of the study’s participants participated in nasal irrigation with tap water, a risky endeavor since Acanthamoeba and other amoebas like it have been found in over 50 percent of US tap water samples.

But many Americans don’t know that. About 33 percent of American adults believe tap water is sterile, and 62 percent believe it is safe to rinse their sinuses.

Acanthamoeba can cause another type of infection, Ancathoamoeba keratitis, which occurs when the amoeba contaminates contact lenses or contact solution.

The brain infection caused by Acanthamoeba should not be confused with Naegleria fowleri, commonly referred to as the brain-eating amoeba, which kills about 97 percent of its victims.

It causes a disease called primary amoebic meningoencephalitis, also known as PAM or amoebic meningitis.

Once Naegleria fowleri enters the nasal passages, it migrates along the olfactory nerve fibers to reach the brain. From there, it causes inflammation and destruction of brain tissue.