Washing sinuses with tap water may give people deadly brain-eating amoeba infection, study warns

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Nasal rinses to relieve sinus congestion using tap water may give people deadly brain-eating amoeba infections, a new study warned.

Researchers from the US Centers for Disease Control and Prevention (CDC) report the cases of 10 people over the last decade who contracted an infection with the amoeba Acanthamoeba after nasal rinsing and three of them died.

All 10 individuals had compromised immune systems and seven suffered from chronic sinusitis, and “many used tap water for nasal rinsing,” according to the study published on Wednesday in the CDC’s Emerging Infectious Diseases journal.

Amoeba are single-celled organisms known to cause parasitic infections in humans, including skin and eye diseases as well as deadly brain infections.

Acanthamoeba is present worldwide, inhabiting soil and many types of water, including lakes, rivers, and tap water.

The amoeba is known to be an opportunistic pathogen, infecting those with weak or compromised immune systems, such as those with diabetes, cancer, HIV, or with a history of organ transplant.

In individuals with weak immune systems, while nasal rinsing can provide health benefits like clearing their sinuses and preventing other types of infection, the process can also introduce pathogens, “particularly if unsterile water is used”, researchers warn.

In another study, published on Wednesday in the same journal, doctors from Karachi point to the case of a 22-year-old Pakistani man who was infected with the amoeba Naegleria fowleri following tap water nasal rinsing that he did as part of a religious ritual.

Brain infections with amoeba can be fatal with very few survivors globally, and the disease also has “no specific treatment”, researchers warn.

But thanks to “aggressive” early medical intervention, the man survived.

Researchers caution that nasal rinsing with tap water may lead to infections caused by amoeba including Acanthamoeba and Naegleria fowleri.

If tap water is used for rinsing, doctors say it should be boiled for a minimum of a minute, or three minutes in elevations over 1,980m, and cooled before use.

“All healthcare providers caring for immunocompromised persons should educate their patients about Acanthamoeba infections, including how to recognize symptoms and how to practice safe nasal rinsing,” they added.