Dec. 16, 2011 -- The Louisiana Department of Health and Hospitals has issued a warning about improper Neti pot use, which has been linked to two deadly infections.

A 51-year-old woman from DeSoto Parish and a 20-year-old man from St. Bernard Parish, a suburb of New Orleans, died after using Neti pots containing tap water to flush their sinuses. Both became infected with Naegleria fowleri, a parasite known as the brain-eating amoeba.

"If you are irrigating, flushing or rinsing your sinuses, for example, by using a Neti pot, use distilled, sterile or previously boiled water to make up the irrigation solution," Louisiana State epidemiologist Dr. Raoult Ratard said in a statement. "Tap water is safe for drinking but not for irrigating your nose."

Naegleria fowleri enters the body through the nose to cause primary amoebic meningoencephalitis -- a brain infection with symptoms similar to those of bacterial meningitis. Headache, fever, nausea and stiff neck swiftly give way to confusion, loss of balance, seizures and hallucinations. And if left untreated, the infection can cause death within one to 12 days.

"The difficulty is that Naegleria is exceedingly rare," said Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center. "It's difficult to diagnose, and once it's diagnosed, it's also difficult to treat."

Most Naegleria fowleri infections result from diving into warm, stagnant water. There were four deaths linked to the parasite last summer, including one in Louisiana.

"I had not heard of Naegleria being associated with Neti pot use, but it's perfectly biologically plausible, because tap water is not sterile," said Schaffner. "And when you inhale it directly into the sinuses, it's similar to a deep dive into brackish water."

Drinking tap water cannot cause a Naegleria fowleri infection.

The Neti pot is an ancient nasal irrigation system that looks like a gravy boat. When used properly, it can help relieve congestion associated with the common cold, the flu and allergies.

"Particularly in the winter, a lot of people get chronic sinusitis and the Neti pot offers a way for the sinuses to drain," said Schaffner. "Some patients seem to benefit; other don't."

Neti pot popularity has grown in recent years, thanks to celebrity backers like Oprah and Dr. Oz. But a 2009 study presented at the American College of Allergy, Asthma and Immunology's annual meeting suggests that Neti pot overuse could increase the risk of sinus infections.

"There's a degree of controversy about whether it should be recommended generally," said Schaffner. "It's one of those treatments that sort of grew up rather than coming to us through rigorous, evidence-based trials. But there are many people out there who swear by it."

The warning from the Louisiana Department of Health and Hospitals highlights the risks of improper Neti pot use. But when used and cleaned properly, the Neti pot is safe, Schaffner said

"Use sterile, boiled [and cooled] or distilled water; rinse [the Neti pot] out thoroughly after use; and air-dry it," he said, adding that water left in the Neti pot after use could become a breeding ground for bacteria and parasites that feed on mucus. "You don't have to send it to an autoclave, but it does require some attention to detail."