Fatal Case of Splash Pad–Associated Naegleria fowleri Meningoencephalitis — Pulaski County, Arkansas, September 2023

Abstract

A fatal case of primary amebic meningoencephalitis (PAM), an infection caused by Naegleria fowleri, was diagnosed in Arkansas in a young child in September 2023. A public health investigation was completed, with epidemiologic, laboratory, and environmental data suggesting that a splash pad (an interactive water play venue that sprays or jets water on users and has little or no standing water) with inadequately disinfected water was the most likely site of the patient’s N. fowleri exposure. This case is the third occurrence of splash pad–associated PAM reported in the United States; all three cases involved inadequately disinfected water. PAM should be considered in patients with acute meningoencephalitis and a history of recent possible exposure to fresh water, including treated recreational water (e.g., in splash pads or pools), via the nasal passages. Proper design, construction, operation, and management of splash pads can help prevent illnesses, including N. fowleri infections. Increased awareness, collaboration, and communication among clinicians, hospitals, laboratories, CDC, health departments, the aquatics sector, and the public can help support N. fowleri infection identification, treatment, prevention, and control efforts.

Case Identification and Clinical Course

On September 1, 2023, a previously healthy child aged 16 months was seen at a local Arkansas hospital with a 3-day history of fever, vomiting, decreased oral intake, decreased activity, and new onset of altered mental status. A noncontrast head computed tomography scan demonstrated ventriculomegaly, a sign concerning for increased intracranial pressure, a possible sequela of meningitis. Empiric treatment for bacterial and viral meningitis was initiated. The patient was admitted to the pediatric intensive care unit for further evaluation and treatment. A lumbar puncture was performed, and findings on laboratory examination of cerebrospinal fluid (CSF) were consistent with possible bacterial meningitis.^§ Qualitative multipathogen nucleic acid–based CSF test results (bioMérieux BioFire FilmArray Meningitis/Encephalitis Panel) were negative; blood and CSF cultures demonstrated no growth after 24 hours. The patient’s clinical condition worsened.

On September 3, pathology review of Wright-Giemsa stained cytospin slides of CSF revealed numerous amebic microorganisms morphologically consistent with Naegleria spp., a free-living ameba that is found in warm fresh water and soil and causes primary amebic meningoencephalitis (PAM) (Figure 1) (1). Family members reported that the patient had played at a splash pad and pool in Pulaski County, Arkansas, on August 26 and 27 (2–3 days before symptom onset). Treatment for Naegleria fowleri infection (amphotericin B, azithromycin, dexamethasone, fluconazole, miltefosine, and rifampin) was started. CDC was consulted, and the case was reported to the Arkansas Department of Health (ADH). CSF specimens were sent to CDC’s Free-Living and Intestinal Amebas (FLIA) Laboratory for further testing. The patient’s condition did not improve, and the patient died on September 4. On September 6, CDC confirmed N. fowleri in the child’s CSF via real-time polymerase chain reaction (PCR) testing.

Public Health Investigation and Response

CDC supported ADH in the case investigation and response. This activity was reviewed by CDC, deemed not research, and was conducted consistent with applicable federal law and CDC policy.^¶

Splash Pad and Pool Site Investigation

On September 3, 2023, an ADH environmental health specialist conducted a site investigation of the splash pad and adjacent pool where the patient had played 2–3 days before symptom onset. The splash pad (Figure 2) used a recirculating system and a separate water feature pump, which pulled water from an underground tank when users activated the splash pad and directed it through a manifold piping system to a series of laminar nozzles that sprayed water up from the deck. After the water fell onto the splash pad, it flowed down a sloped surface into a return drain lining the perimeter and was plumbed back into the tank. A recirculating pump then pulled water from this tank and sent it through a sand filter and, subsequently, calcium hypochlorite tablets and sodium bisulfate tablets were added by a chlorinator and dry acid feeder,** respectively. The water was then returned to the tank until being recirculated again, or until a user activated the splash pad again. The splash pad water source was municipal potable water; in addition, water was also occasionally pumped via hose directly from the pool into the splash pad tank. Overflow outlet piping drained from the splash pad tank to a storm drain and helped prevent the tank from flooding.

Multiple code violations related to the splash pad were noted. The pH exceeded the test kit measurement limit of 8.2^††; the residual chlorine concentration exceeded the test kit limit of 5 ppm^§§; the chlorinator was reported as nonfunctional for approximately 1 month, and chlorine was being hand-fed daily^¶¶; no daily operational records were maintained or available for review.***

The pool used a separate, similarly laid out recirculating system that also included a surge tank.^††† Multiple code violations related to the pool were also noted. The pH was >8.2, the test kit upper measurement limit; the pool flow meter was not operating correctly^§§§; pool water from a large leak in the equipment room was being pumped into the pool surge pit; and no daily operational records were maintained. The splash pad and pool were closed after the investigation.

Environmental Sampling

Environmental swab samples (from the splash pad [drains, laminar nozzles, and biofilm in the tank] and pool [gutter drains and biofilm near the pool leak]) and bulk water samples (from the splash pad tank, pool, pool leak area, and source water from a deck hose) were collected and sent to CDC’s Environmental Microbiology and Engineering Laboratory for testing using temperature-selected culture followed by molecular confirmation (2). On September 13, viable N. fowleri were detected in the swab collected from the splash pad tank. On September 14, ADH issued a press release notifying the public of a fatal case of N. fowleri infection and included information about the public health investigation, N. fowleri, and symptoms of infection.^¶¶¶ On September 21, viable thermophilic amebas were detected in the bulk water collected from the splash pad tank and pool; Naegleria spp. were not detected in these bulk water samples.

Additional Laboratory Investigation and Actions Taken

At CDC’s FLIA Laboratory, a genomic typing method using Sanger sequencing of the ITS1 loci region was conducted to compare the clinical and environmental amebas’ genetic relatedness (3). On September 28, the N. fowleri cultured from the patient’s CSF and the splash pad tank were confirmed to both be genotype III. Together, the epidemiologic, laboratory, and environmental data suggest the splash pad was the most likely site of the patient’s exposure to N. fowleri.

The splash pad was disabled and is no longer in use. Corrective actions**** were taken to address the code violations identified during the pool site investigation. A follow-up inspection of the pool was completed on June 3, 2024, and a new operating permit was issued.

Discussion

Naegleria fowleri infections are rare and often fatal; among 164 persons known to have been infected in the United States during 1962–2023, only four (2.4%) have survived (1). Infection can occur when water containing the N. fowleri ameba enters the body through the nose (1). Symptoms typically begin 1–12 days after exposure; PAM progresses rapidly and can lead to brain tissue destruction, brain swelling, and death 1–18 days after symptom onset (median = 5 days) (1). Most N. fowleri infections have been associated with recreational exposure to fresh water (e.g., swimming or diving in a lake) during summer months (1). During 2020–2021, two children in Texas died from PAM after playing at separate “splash pads” with inadequately disinfected water: one was a single-pass, decorative fountain used as a splash pad by the public but not designed, constructed, operated, or managed as a splash pad, and the other was a splash pad that used recirculated water and was not adequately monitored (4,5). The splash pad–associated PAM case described here represents the third such case in 4 years, indicating that splash pads with inadequately disinfected water are an emerging exposure of concern for transmission of N. fowleri.

Clinical diagnosis of PAM is difficult because early signs and symptoms can be nonspecific, and manifestations, including CSF findings, might mimic bacterial meningitis (6). PAM should be considered in patients evaluated for acute meningoencephalitis who have a history of recent possible exposure to fresh water, including treated recreational water (e.g., in splash pads or pools), via nasal passages. Prompt diagnosis and treatment are critical to improving chances of survival. N. fowleri can be identified in CSF smears or cultures via direct visualization under a microscope using hematoxylin and eosin, periodic acid-Schiff, trichrome, Giemsa, or Wright-Giemsa stains; Gram stain is not sufficient for diagnosis, as N. fowleri can be destroyed during heat fixation (7). Confirmatory testing (PCR, immunohistochemistry, or indirect immunofluorescent staining) is available at selected U.S. laboratories, including CDC’s FLIA Laboratory^†††† (7). The recommended treatment of N. fowleri infections is based on medications used in PAM survivors and those medications with demonstrated antiamebic activity against N. fowleri in the laboratory.^§§§§

Proper design, construction, operation, and management of splash pads can help prevent transmission of pathogens, including N. fowleri (8). In this case, because no operational records were maintained and the chlorinator was reported as being nonfunctional for approximately 1 month, it is possible that inadequate disinfection of the splash pad was a chronic problem. Inadequate disinfection, operation, and management over time could lead to growth of biofilm, which can supply nutrients for free-living ameba as well as protection from disinfectants (9). CDC’s Model Aquatic Health Code provides evidence-based recommendations that jurisdictions and the aquatics sector can collaborate on voluntarily adopting to promote healthy swimming at splash pads, pools, and other treated recreational water venues open to the public (Box) (10). Healthy and safe swimming recommendations and resources for the public are also available (4).

Although PAM is not a nationally notifiable disease, it is reportable in some jurisdictions, and CDC tracks N. fowleri infections with the voluntary assistance of health departments to monitor disease trends and guide public health recommendations.^¶¶¶¶ Ongoing collaboration and communication among clinicians, hospitals, laboratories, CDC, health departments, the aquatics sector, and the public can support efforts to identify, treat, prevent, and control N. fowleri infections.