N. fowleri regularly connected with lakes, ponds, and rivers.

Two current cases of primary amoebic meningoencephalitis (PAM) show that municipal tap water can harbor the ameba responsible for the fatal disease, according to CDC specialists.

The deaths of two adults in Louisiana hospitals of infectious meningoencephalitis are the first recorded PAM cases in the country associated with the presence of Naegleria fowleri in household plumbing served by treated municipal water, wrote Jonathan Yoder, MPH, of the CDC’s National Center for Emerging and Zoonotic Infectious Diseases in Atlanta, and colleagues in Clinical Infectious Diseases online.

The cases also are the first reports of a potential link between PAM and the use of a nasal irrigation device, the group added. As a result, the CDC recommended that patients who use a neti pot or similar device for nasal irrigation distil, filter, or boil the municipally treated tap water before use.

The authors noted that tap water in the U.S. has not historically been a common source of exposure to N. fowleri, a free-living ameba commonly found in warm, typically untreated freshwater such as lakes, ponds, and rivers. However, it also can be found in warm groundwater and deficiently treated swimming pools.

PAM symptom onset occurs 1 to 7 days after introduction, and symptoms of infection are similar to bacterial or viral meningitis, including fever, a headache, stiff neck, vomiting, anorexia, seizures, altered mental state, and coma.

In the first case, a 28-year-old man abruptly developed symptoms of severe occidental headache radiating down the neck, neck stiffness, back pain, and intermittent vomiting, as well as fever, confusion, and disorientation at admission to the emergency department.

“The patient had chronic allergic sinusitis and irritated his sinuses with a neti pot at least any event once a day, using tap water to which he added a commercially available salt packet,” the authors explained.

Several amoebae were detected in samples taken from the patient’s home, including Hartmannella, Vanilla, and Naegleria sp. Water collected from a tankless water heater was polymerase chain reaction (PCR) positive for N. fowleri, although the neti pot was PCR negative for N. fowleri.

In the second case, a 51-year-old woman had presented symptoms over 3 days of altered mental status, nausea, vomiting, poor appetite, listlessness, fatigue, and high fever, as well as neck stiffness and thyromegaly upon examination at an emergency department.

She also had sinus problems and regularly used a neti pot. Water samples from the kitchen faucet, shower, bathtub, and bathroom sink in her home tested positive for N. fowleri.

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