Bonnie Mull

Primary Amebic Meningoencephalitis Deaths Associated With Sinus Irrigation Using Contaminated Tap Water

BACKGROUND Naegleria fowleri is a climate-sensitive, thermophilic ameba found in the environment, including warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri-containing water enters the nose, typically during swimming, and N. fowleri migrates to the brain via the olfactory nerve. In 2011, 2 adults died in Louisiana hospitals of infectious meningoencephalitis after brief illnesses. METHODS Clinical and environmental testing and case investigations were initiated to determine the cause of death and to identify the exposures. RESULTS Both patients had diagnoses of PAM. Their only reported water exposures were tap water used for household activities, including regular sinus irrigation with neti pots. Water samples, tap swab samples, and neti pots were collected from both households and tested; N. fowleri were identified in water samples from both homes. CONCLUSIONS These are the first reported PAM cases in the United States associated with the presence of N. fowleri in household plumbing served by treated municipal water supplies and the first reports of PAM potentially associated with the use of a nasal irrigation device. These cases occurred in the context of an expanding geographic range for PAM beyond southern tier states with recent case reports from Minnesota, Kansas, and Virginia. These infections introduce an additional consideration for physicians recommending nasal irrigation and demonstrate the importance of using appropriate water (distilled, boiled, filtered) for nasal irrigation. Furthermore, the changing epidemiology of PAM highlights the importance of raising awareness about this disease among physicians treating persons showing meningitislike symptoms.

Recovery and detection of Escherichia coli O157:H7 in surface water, using ultrafiltration and real-time PCR.

ABSTRACT Enterohemorrhagic Escherichia coli O157:H7 (EHEC O157:H7) outbreaks have revealed the need for improved analytical techniques for environmental samples. Ultrafiltration (UF) is increasingly recognized as an effective procedure for concentrating and recovering microbes from large volumes of water and treated wastewater. This study describes the application of hollow-fiber UF as the primary step for concentrating EHEC O157:H7 seeded into 40-liter samples of surface water, followed by an established culture/immunomagnetic-separation (IMS) method and a suite of real-time PCR assays. Three TaqMan assays were used to detect the stx1, stx2, and rfbE gene targets. The results from this study indicate that approximately 50 EHEC O157:H7 cells can be consistently recovered from a 40-liter surface water sample and detected by culture and real-time PCR. Centrifugation was investigated and shown to be a viable alternative to membrane filtration in the secondary culture/IMS step when water quality limits the volume of water that can be processed by a filter. Using multiple PCR assay sets to detect rfbE, stx1, and stx2 genes allowed for specific detection of EHEC O157:H7 from strains that do not possess all three genes. The reported sample collection and analysis procedure should be a sensitive and effective tool for detecting EHEC O157:H7 in response to outbreaks of disease associated with contaminated water.

The First Association of a Primary Amebic Meningoencephalitis Death With Culturable Naegleria fowleri in Tap Water From a US Treated Public Drinking Water System

BACKGROUND Naegleria fowleri is a climate-sensitive, thermophilic ameba found in warm, freshwater lakes and rivers. Primary amebic meningoencephalitis (PAM), which is almost universally fatal, occurs when N. fowleri-containing water enters the nose, typically during swimming, and migrates to the brain via the olfactory nerve. In August 2013, a 4-year-old boy died of meningoencephalitis of unknown etiology in a Louisiana hospital. METHODS Clinical and environmental testing and a case investigation were initiated to determine the cause of death and to identify potential exposures. RESULTS Based on testing of cerebrospinal fluid and brain specimens, the child was diagnosed with PAM. His only reported water exposure was tap water; in particular, tap water that was used to supply water to a lawn water slide on which the child had played extensively prior to becoming ill. Water samples were collected from both the home and the water distribution system that supplied the home and tested; N. fowleri was identified in water samples from both the home and the water distribution system. CONCLUSIONS This case is the first reported PAM death associated with culturable N. fowleri in tap water from a US treated drinking water system. This case occurred in the context of an expanding geographic range for PAM beyond southern states, with recent case reports from Minnesota, Kansas, and Indiana. This case also highlights the role of adequate disinfection throughout drinking water distribution systems and the importance of maintaining vigilance when operating drinking water systems using source waters with elevated temperatures.

Recovery of diverse microbes in high turbidity surface water samples using dead-end ultrafiltration

Dead-end ultrafiltration (DEUF) has been reported to be a simple, field-deployable technique for recovering bacteria, viruses, and parasites from large-volume water samples for water quality testing and waterborne disease investigations. While DEUF has been reported for application to water samples having relatively low turbidity, little information is available regarding recovery efficiencies for this technique when applied to sampling turbid water samples such as those commonly found in lakes and rivers. This study evaluated the effectiveness of a DEUF technique for recovering MS2 bacteriophage, enterococci, Escherichia coli, Clostridium perfringens, and Cryptosporidium parvum oocysts in surface water samples having elevated turbidity. Average recovery efficiencies for each study microbe across all turbidity ranges were: MS2 (66%), C. parvum (49%), enterococci (85%), E. coli (81%), and C. perfringens (63%). The recovery efficiencies for MS2 and C. perfringens exhibited an inversely proportional relationship with turbidity, however no significant differences in recovery were observed for C. parvum, enterococci, or E. coli. Although ultrafilter clogging was observed, the DEUF method was able to process 100-L surface water samples at each turbidity level within 60 min. This study supports the use of the DEUF method for recovering a wide array of microbes in large-volume surface water samples having medium to high turbidity.

Improved Method for the Detection and Quantification of Naegleria fowleri in Water and Sediment Using Immunomagnetic Separation and Real-Time PCR

Primary amebic meningoencephalitis (PAM) is a rare and typically fatal infection caused by the thermophilic free-living ameba, Naegleria fowleri. In 2010, the first confirmed case of PAM acquired in Minnesota highlighted the need for improved detection and quantification methods in order to study the changing ecology of N. fowleri and to evaluate potential risk factors for increased exposure. An immunomagnetic separation (IMS) procedure and real-time PCR TaqMan assay were developed to recover and quantify N. fowleri in water and sediment samples. When one liter of lake water was seeded with N. fowleri strain CDC:V212, the method had an average recovery of 46% and detection limit of 14 amebas per liter of water. The method was then applied to sediment and water samples with unknown N. fowleri concentrations, resulting in positive direct detections by real-time PCR in 3 out of 16 samples and confirmation of N. fowleri culture in 6 of 16 samples. This study has resulted in a new method for detection and quantification of N. fowleri in water and sediment that should be a useful tool to facilitate studies of the physical, chemical, and biological factors associated with the presence and dynamics of N. fowleri in environmental systems.

Environmental Surveillance for Toxigenic Vibrio cholerae in Surface Waters of Haiti

Epidemic cholera was reported in Haiti in 2010, with no information available on the occurrence or geographic distribution of toxigenic Vibrio cholerae in Haitian waters. In a series of field visits conducted in Haiti between 2011 and 2013, water and plankton samples were collected at 19 sites. Vibrio cholerae was detected using culture, polymerase chain reaction, and direct viable count methods (DFA-DVC). Cholera toxin genes were detected by polymerase chain reaction in broth enrichments of samples collected in all visits except March 2012. Toxigenic V. cholerae was isolated from river water in 2011 and 2013. Whole genome sequencing revealed that these isolates were a match to the outbreak strain. The DFA-DVC tests were positive for V. cholerae O1 in plankton samples collected from multiple sites. Results of this survey show that toxigenic V. cholerae could be recovered from surface waters in Haiti more than 2 years after the onset of the epidemic.

Assessment of Drinking Water Sold from Private Sector Kiosks in Post-Earthquake Port-au-Prince, Haiti

Abstract. Consumption of drinking water from private vendors has increased considerably in Port-au-Prince, Haiti, in recent decades. A major type of vendor is private kiosks, advertising reverse osmosis-treated water for sale by volume. To describe the scale and geographical distribution of private kiosks in metropolitan Port-au-Prince, an inventory of private kiosks was conducted from July to August 2013. Coordinates of kiosks were recorded with global positioning system units and a brief questionnaire was administered with the operator to document key kiosk characteristics. To assess the quality of water originating from private kiosks, water quality analyses were also conducted on a sample of those inventoried as well as from the major provider company sites. The parameters tested were Escherichia coli, free chlorine residual, pH, turbidity, and total dissolved solids. More than 1,300 kiosks were inventoried, the majority of which were franchises of four large provider companies. Approximately half of kiosks reported opening within 12 months of the date of the inventory. The kiosk treatment chain and sales price was consistent among a majority of the kiosks. Of the 757 kiosks sampled for water quality, 90.9% of samples met World Health Organization (WHO) microbiological guideline at the point of sale for nondetectable E. coli in a 100-mL sample. Of the eight provider company sites tested, all samples met the WHO microbiological guideline. Because of the increasing role of the private sector in drinking water provision in Port-au-Prince and elsewhere in Haiti, this assessment was an important first step for government regulation of this sector.