Fatal Naegleria fowleri Infection After Nasal Rinsing With RV Tap Water, Texas, 2024

Primary amebic meningoencephalitis (PAM) is a rare, usually fatal brain infection caused by the free-living ameba Naegleria fowleri. Most infections follow swimming and other recreational water, but using tap water for nasal irrigation is also a risk. Poorly maintained municipal and recreational vehicle (RV) water systems can spread waterborne disease.

The case

• A previously healthy 71-year-old woman used a nasal irrigation device filled with tap water from her RV's water system at a campground in Texas — several times in the 4 days before she fell ill, with unboiled water from the RV's drinking-water faucet.
• Within 4 days she developed fever, headache and altered mental status. Despite treatment for suspected PAM, she had seizures and died 8 days after symptoms began.
• CDC confirmed N. fowleri in her cerebrospinal fluid. She had no recreational freshwater exposure.

Two possible sources

The Texas Department of State Health Services identified two:

1. The RV's drinking-water tank, feeding the faucets and shower when no municipal hookup was available. It had been filled on an unknown date before she bought the RV 3 months earlier.
2. The campground's municipal water, connected by hose and filter straight to the RV's plumbing — bypassing the tank — when she did her nasal rinses.

What the testing showed

Investigators took 12 samples: her squirt bottle; 1 liter from the RV water heater; swabs of the shower head and kitchen and bathroom faucets; about 4 gallons (15 L) filtered from the RV tank, and a tank swab; about 26 gallons (100 L) filtered from the campsite hookup, and a swab; the RV's external filter and hose; and another 26 gallons (100 L) from a low-flow, dead-end campsite connection.

• No N. fowleri — neither its DNA nor live amebas — was found anywhere.
• But the water was poorly disinfected:
• • total chlorine and monochloramine at the dead-end campsite connection were both under 0.04 mg/L, far below Texas's recommended minimum of 0.50 mg/L;
  • free ammonia, low pH (under 8.5) and a gap between monochloramine and total chlorine pointed to weak disinfection, which can let biofilm grow — biofilm shields microbes, amebas included, from disinfectant;
  • turbidity (cloudiness) at the taps and in the RV was 1.26–4.32 NTU, above the under 1.0 recommended for drinking water — a sign of disinfection breakdown.

Conclusions

Tap water used for nasal rinsing remains the suspected route, given no other nasal water exposure and the poor water quality. The ameba may not have been found because sampling came 23 days after her rinses, when conditions may have changed, or because it was present below detectable levels. Whether the municipal supply or the RV tank was the source is unknown — the tank could have contaminated the RV's plumbing before the hookup.

Prevention:

• For nasal irrigation, use only distilled, sterile, or boiled and cooled tap water.
• Maintain RV water systems, and follow safe household water practices with them.
• Municipal systems must meet regulatory standards.

Texas health officials and CDC waterborne disease experts have since written recommendations for safer RV water use and storage.

Sources

Based on Smith OA, Tillman W, Lewis JB, et al., "Notes from the Field: Primary Amebic Meningoencephalitis Associated with Nasal Irrigation Using Water from a Recreational Vehicle — Texas, 2024," MMWR Morbidity and Mortality Weekly Report, volume 74, Centers for Disease Control and Prevention; a work of the United States government in the public domain.