Important warning: Rinsing the nose with tap water may lead to a fatal brain infection

A new study warns that rinsing the nose to relieve sinus congestion with tap water may lead to a deadly infection called "brain-eating amoeba."

US Centers for Disease Control and Prevention (CDC) researchers reported 10 cases of people becoming infected with Acanthamoeba after nasal rinses over the past decade, and three of them died.

All 10 individuals suffered from a weak immune system, and 7 people suffered from chronic sinusitis.

The single-celled amoeba is known to cause parasitic infections in humans, including skin and eye diseases and fatal brain infections.

Acanthamoeba is found throughout the world, inhabiting soil, lakes, rivers and tap water.

Researchers warn that brain infections resulting from amoeba infection can be fatal, with very few survivors worldwide, and the disease has no specific treatment.

While nasal rinsing can provide health benefits such as clearing your sinuses and preventing other types of infections, the process can also lead to the introduction of pathogens, especially when using unsterile water.

If tap water is used for rinsing, doctors say it should be boiled for at least one or three minutes, then cooled before use.

They added: "All healthcare providers of immunocompromised people should educate their patients about Acanthamoeba infection, including how to recognize symptoms and practice safe nasal rinsing."

In another study, a team of doctors revealed the case of a 22-year-old Pakistani man who became infected with the amoeba Naegleria fowleri after washing his nose with tap water as part of a religious ritual. But the young man survived thanks to early medical intervention.

The study was published in the Centers for Disease Control and Prevention's Emerging Infectious Diseases journal.