Wilderness Medical Society Clinical Practice Guidelines on Water Treatment for Wilderness, International Travel, and Austere Situations: 2024 Update

To provide guidance to medical providers, wilderness users, and travelers, the Wilderness Medical Society convened an expert panel to develop evidence-based guidelines for treating water in situations where the potability of available water is not assured, including wilderness and international travel, areas impacted by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiological contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence base includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks/burdens according to the criteria published by the American College of Chest Physicians.

Estimating Waterborne Infectious Disease Burden by Exposure Route, United States, 2014

More than 7.15 million cases of domestically acquired infectious waterborne illnesses occurred in the United States in 2014, causing 120,000 hospitalizations and 6,600 deaths. We estimated disease incidence for 17 pathogens according to recreational, drinking, and nonrecreational nondrinking (NRND) water exposure routes by using previously published estimates. In 2014, a total of 5.61 million (95% credible interval [CrI] 2.97-9.00 million) illnesses were linked to recreational water, 1.13 million (95% CrI 255,000-3.54 million) to drinking water, and 407,000 (95% CrI 72,800-1.29 million) to NRND water. Recreational water exposure was responsible for 36%, drinking water for 40%, and NRND water for 24% of hospitalizations from waterborne illnesses. Most direct costs were associated with pathogens found in biofilms. Estimating disease burden by water exposure route helps direct prevention activities. For each exposure route, water management programs are needed to control biofilm-associated pathogen growth; public health programs are needed to prevent biofilm-associated diseases.

Using Wastewater Surveillance Data to Support the COVID-19 Response - United States, 2020-2021

Wastewater surveillance, the measurement of pathogen levels in wastewater, is used to evaluate community-level infection trends, augment traditional surveillance that leverages clinical tests and services (e.g., case reporting), and monitor public health interventions (1). Approximately 40% of persons infected with SARS-CoV-2, the virus that causes COVID-19, shed virus RNA in their stool (2); therefore, community-level trends in SARS-CoV-2 infections, both symptomatic and asymptomatic (2) can be tracked through wastewater testing (3-6). CDC launched the National Wastewater Surveillance System (NWSS) in September 2020 to coordinate wastewater surveillance programs implemented by state, tribal, local, and territorial health departments to support the COVID-19 pandemic response. In the United States, wastewater surveillance was not previously implemented at the national level. As of August 2021, NWSS includes 37 states, four cities, and two territories. This report summarizes NWSS activities and describes innovative applications of wastewater surveillance data by two states, which have included generating alerts to local jurisdictions, allocating mobile testing resources, evaluating irregularities in traditional surveillance, refining health messaging, and forecasting clinical resource needs. NWSS complements traditional surveillance and enables health departments to intervene earlier with focused support in communities experiencing increasing concentrations of SARS-CoV-2 in wastewater. The ability to conduct wastewater surveillance is not affected by access to health care or the clinical testing capacity in the community. Robust, sustainable implementation of wastewater surveillance requires public health capacity for wastewater testing, analysis, and interpretation. Partnerships between wastewater utilities and public health departments are needed to leverage wastewater surveillance data for the COVID-19 response for rapid assessment of emerging threats and preparedness for future pandemics.

Detection and identification of Giardia species using real-time PCR and sequencing

We report a specific region of Giardia spp. 18S ribosomal RNA (18S rDNA) that serves as an ideal target for quantitative PCR (qPCR) detection and sequencing to identify Giardia species, including the clinically-relevant G. duodenalis, in clinical and environmental samples. The presence of multiple copies of the 18S rDNA gene and variations in the selected 18S genomic region enabled the development of a rapid, sensitive qPCR screening method for the detection of Giardia spp. The analytical sensitivity of the Giardia qPCR assay was determined to be a cyst equivalent of 0.4 G. duodenalis cysts per PCR reaction. Amplicon sequencing of the PCR product confirmed Giardia spp. detection and among the 35 sequences obtained, 31, 3 and 1 isolates were classified as belonging to G. duodenalis, G. microti and G. muris, respectively. The TaqMan assay reported here may be useful for the detection of low levels of Giardia in clinical and environmental samples, and further enables the effective use of direct sequencing of the PCR product for Giardia confirmation and to identify major species of Giardia, including G. duodenalis.

Estimate of Burden and Direct Healthcare Cost of Infectious Waterborne Disease in the United States

Provision of safe drinking water in the United States is a great public health achievement. However, new waterborne disease challenges have emerged (e.g., aging infrastructure, chlorine-tolerant and biofilm-related pathogens, increased recreational water use). Comprehensive estimates of the health burden for all water exposure routes (ingestion, contact, inhalation) and sources (drinking, recreational, environmental) are needed. We estimated total illnesses, emergency department (ED) visits, hospitalizations, deaths, and direct healthcare costs for 17 waterborne infectious diseases. About 7.15 million waterborne illnesses occur annually (95% credible interval [CrI] 3.88 million–12.0 million), results in 601,000 ED visits (95% CrI 364,000–866,000), 118,000 hospitalizations (95% CrI 86,800–150,000), and 6,630 deaths (95% CrI 4,520–8,870) and incurring US $3.33 billion (95% CrI 1.37 billion–8.77 billion) in direct healthcare costs. Otitis externa and norovirus infection were the most common illnesses. Most hospitalizations and deaths were caused by biofilm-associated pathogens (nontuberculous mycobacteria, Pseudomonas, Legionella), costing US $2.39 billion annually.

Characteristics Associated with Adults Remembering to Wash Hands in Multiple Situations Before and During the COVID-19 Pandemic - United States, October 2019 and June 2020

Washing hands often, especially during times when one is likely to acquire and spread pathogens,* is one important measure to help prevent the spread of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), as well as other pathogens spread by respiratory or fecal-oral transmission (1,2). Studies have reported moderate to high levels of self-reported handwashing among adults worldwide during the COVID-19 pandemic (3-5)^†; however, little is known about how handwashing behavior among U.S. adults has changed since the start of the pandemic. For this study, survey data from October 2019 (prepandemic) and June 2020 (during pandemic) were compared to assess changes in adults' remembering to wash their hands in six situations.^§ Statistically significant increases in reported handwashing were seen in June 2020 compared with October 2019 in four of the six situations; the odds of remembering to wash hands was 2.3 times higher among respondents after coughing, sneezing, or blowing their nose, 2.0 times higher before eating at a restaurant, and 1.7 times higher before eating at home. Men, young adults aged 18-24 years, and non-Hispanic White (White) adults were less likely to remember to wash hands in multiple situations. Strategies to help persons remember to wash their hands frequently and at important times should be identified and implemented, especially among groups reporting low prevalence of remembering to wash their hands.

Detection of Cryptosporidium Recovered from Large-Volume Water Samples Using Dead-End Ultrafiltration

The procedure described here provides instructions for detection of Cryptosporidium recovered from large-volume water samples. Water samples are collected by dead-end ultrafiltration in the field and ultrafilters are processed in a laboratory. Microbes recovered from the filters are further concentrated and subjected to Cryptosporidium isolation or nucleic acid extraction methods for the detection of Cryptosporidium oocysts or Cryptosporidium DNA.

Wilderness Medical Society Clinical Practice Guidelines for Water Disinfection for Wilderness, International Travel, and Austere Situations

To provide guidance to clinicians, the Wilderness Medical Society convened experts to develop evidence-based guidelines for water disinfection in situations where the potability of available water is not ensured, including wilderness and international travel, areas affected by disaster, and other areas without adequate sanitation. The guidelines present the available methods for reducing or eliminating microbiologic contamination of water for individuals, groups, or households; evaluation of their effectiveness; and practical considerations. The evidence evaluation includes both laboratory and clinical publications. The panel graded the recommendations based on the quality of supporting evidence and the balance between benefits and risks or burdens, according to the criteria published by the American College of Chest Physicians.

Efficacy of a solar concentrator to Inactivate E. coli and C. perfringens spores in latrine waste in Kenya

Alternative sanitation options are needed for effective waste management in low-income countries where centralized, large-scale waste treatment is not easily achievable. A newly designed solar concentrator technology utilizes solar thermal energy to treat feces contained in drums. This pilot study assessed the efficacy of the new design to inactivate microbes in 13 treatment drums under field conditions in Kenya. Three-quarters of the drums contained <1000 E. coli/g of total solids following 6 h of solar thermal treatment and inactivation of thermotolerant C. perfringens spores ranged from <1.8 to >5.0 log₁₀. Nearly all (94%) samples collected from treatment drums achieved thermophilic temperatures (>50 °C) during the treatment period, however this alone did not ensure samples met the WHO E. coli guideline; higher, sustained thermophilic temperatures tended to be more effective in reaching this guideline. The newly designed solar concentrator was capable of inactivating thermotolerant, environmentally-stable microorganisms as, or possibly more, efficiently than a previous design. Additional data are needed to better characterize how temperature, time, and other parameters affect the ability of the solar concentrator to inactivate microbes in feces.

Primary Amebic Meningoencephalitis Associated With Rafting on an Artificial Whitewater River: Case Report and Environmental Investigation

Background

Naegleria fowleri is a thermophilic ameba found in freshwater that causes primary amebic meningoencephalitis (PAM) when it enters the nose and migrates to the brain. Patient exposure to water containing the ameba typically occurs in warm freshwater lakes and ponds during recreational water activities. In June 2016, an 18-year-old woman died of PAM after traveling to North Carolina, where she participated in rafting on an artificial whitewater river.

Methods

We conducted an epidemiologic and environmental investigation to determine the water exposure that led to the death of this patient.

Results

The case patient's most probable water exposure occurred while rafting on an artificial whitewater river during which she was thrown out of the raft and submerged underwater. The approximately 11.5 million gallons of water in the whitewater facility were partially filtered, subjected to ultraviolet light treatment, and occasionally chlorinated. Heavy algal growth was noted. Eleven water-related samples were collected from the facility; all were positive for N. fowleri. Of 5 samples collected from the nearby natural river, 1 sediment sample was positive for N. fowleri.

Conclusions

This investigation documents a novel exposure to an artificial whitewater river as the likely exposure causing PAM in this case. Conditions in the whitewater facility (warm, turbid water with little chlorine and heavy algal growth) rendered the water treatment ineffective and provided an ideal environment for N. fowleri to thrive. The combination of natural and engineered elements at the whitewater facility created a challenging environment to control the growth of N. fowleri.

Response and remediation actions following the detection of Naegleria fowleri in two treated drinking water distribution systems, Louisiana, 2013-2014

Naegleria fowleri causes the usually fatal disease primary amebic meningoencephalitis (PAM), typically in people who have been swimming in warm, untreated freshwater. Recently, some cases in the United States were associated with exposure to treated drinking water. In 2013, a case of PAM was reported for the first time in association with the exposure to water from a US treated drinking water system colonized with culturable N. fowleri. This system and another were found to have multiple areas with undetectable disinfectant residual levels. In response, the water distribution systems were temporarily converted from chloramine disinfection to chlorine to inactivate N. fowleri and reduced biofilm in the distribution systems. Once >1.0 mg/L free chlorine residual was attained in all systems for 60 days, water testing was performed; N. fowleri was not detected in water samples after the chlorine conversion. This investigation highlights the importance of maintaining adequate residual disinfectant levels in drinking water distribution systems. Water distribution system managers should be knowledgeable about the ecology of their systems, understand potential water quality changes when water temperatures increase, and work to eliminate areas in which biofilm growth may be problematic and affect water quality.

Water quality, availability, and acute gastroenteritis on the Navajo Nation - a pilot case-control study

The Navajo Nation includes approximately 250,000 American Indians living in a remote high desert environment with limited access to public water systems. We conducted a pilot case-control study to assess associations between acute gastroenteritis (AGE) and water availability, use patterns, and quality. Case patients with AGE and non-AGE controls who presented for care to two Indian Health Service hospitals were recruited. Data on demographics and water use practices were collected using a standard questionnaire. Household drinking water was tested for presence of pathogens, coliforms, and residual chlorine. Sixty-one subjects (32 cases and 29 controls) participated in the study. Cases and controls were not significantly different with respect to water sources, quality, or patterns of use. Twenty-one percent (n = 12) of study participants resided in dwellings not connected to a community water system. Eleven percent (n = 7) of subjects reported drinking hauled water from unregulated sources. Coliform bacteria were present in 44% (n = 27) of household water samples, and 68% (n = 40) of samples contained residual chlorine concentrations of <0.2 mg/L. This study highlights issues with water availability, quality, and use patterns within the Navajo Nation, including sub-optimal access to community water systems, and use of water hauled from unregulated sources.

Outbreaks Associated with Untreated Recreational Water - United States, 2000-2014

Outbreaks associated with untreated recreational water can be caused by pathogens, toxins, or chemicals in fresh water (e.g., lakes, rivers) or marine water (e.g., ocean). During 2000-2014, public health officials from 35 states and Guam voluntarily reported 140 untreated recreational water-associated outbreaks to CDC. These outbreaks resulted in at least 4,958 cases of disease and two deaths. Among the 95 outbreaks with a confirmed infectious etiology, enteric pathogens caused 80 (84%); 21 (22%) were caused by norovirus, 19 (20%) by Escherichia coli, 14 (15%) by Shigella, and 12 (13%) by Cryptosporidium. Investigations of these 95 outbreaks identified 3,125 cases; 2,704 (87%) were caused by enteric pathogens, including 1,459 (47%) by norovirus, 362 (12%) by Shigella, 314 (10%) by Cryptosporidium, and 155 (5%) by E. coli. Avian schistosomes were identified as the cause in 345 (11%) of the 3,125 cases. The two deaths were in persons affected by a single outbreak (two cases) caused by Naegleria fowleri. Public parks (50 [36%]) and beaches (45 [32%]) were the leading settings associated with the 140 outbreaks. Overall, the majority of outbreaks started during June-August (113 [81%]); 65 (58%) started in July. Swimmers and parents of young swimmers can take steps to minimize the risk for exposure to pathogens, toxins, and chemicals in untreated recreational water by heeding posted advisories closing the beach to swimming; not swimming in discolored, smelly, foamy, or scummy water; not swimming while sick with diarrhea; and limiting water entering the nose when swimming in warm freshwater.

Outbreaks Associated with Treated Recreational Water - United States, 2000-2014

Outbreaks associated with exposure to treated recreational water can be caused by pathogens or chemicals in venues such as pools, hot tubs/spas, and interactive water play venues (i.e., water playgrounds). During 2000-2014, public health officials from 46 states and Puerto Rico reported 493 outbreaks associated with treated recreational water. These outbreaks resulted in at least 27,219 cases and eight deaths. Among the 363 outbreaks with a confirmed infectious etiology, 212 (58%) were caused by Cryptosporidium (which causes predominantly gastrointestinal illness), 57 (16%) by Legionella (which causes Legionnaires' disease, a severe pneumonia, and Pontiac fever, a milder illness with flu-like symptoms), and 47 (13%) by Pseudomonas (which causes folliculitis ["hot tub rash"] and otitis externa ["swimmers' ear"]). Investigations of the 363 outbreaks identified 24,453 cases; 21,766 (89%) were caused by Cryptosporidium, 920 (4%) by Pseudomonas, and 624 (3%) by Legionella. At least six of the eight reported deaths occurred in persons affected by outbreaks caused by Legionella. Hotels were the leading setting, associated with 157 (32%) of the 493 outbreaks. Overall, the outbreaks had a bimodal temporal distribution: 275 (56%) outbreaks started during June-August and 46 (9%) in March. Assessment of trends in the annual counts of outbreaks caused by Cryptosporidium, Legionella, or Pseudomonas indicate mixed progress in preventing transmission. Pathogens able to evade chlorine inactivation have become leading outbreak etiologies. The consequent outbreak and case counts and mortality underscore the utility of CDC's Model Aquatic Health Code (https://www.cdc.gov/mahc) to prevent outbreaks associated with treated recreational water.

Pool water quality and prevalence of microbes in filter backwash from metro-Atlanta swimming pools

During the 2012 summer swim season, aquatic venue data and filter backwash samples were collected from 127 metro-Atlanta pools. Last-recorded water chemistry measures indicated 98% (157/161) of samples were from pools with ≥1 mg/L residual chlorine without stabilized chlorine or ≥2 mg/L with stabilized chlorine and 89% (144/161) had pH readings 7.2-7.8. These water quality parameters are consistent with the 2016 Model Aquatic Health Code (2nd edition) recommendations. We used previously validated real-time polymerase chain reaction assays for detection of seven enteric microbes, including Escherichia coli, and Pseudomonas aeruginosa. E. coli was detected in 58% (93/161) of samples, signifying that swimmers likely introduced fecal material into pool water. P. aeruginosa was detected in 59% (95/161) of samples, indicating contamination from swimmers or biofilm growth on surfaces. Cryptosporidium spp. and Giardia duodenalis were each detected in approximately 1% of samples. These findings indicate the need for aquatics staff, state and local environmental health practitioners, and swimmers to each take steps to minimize the risk of transmission of infectious pathogens.

Methodological approaches for monitoring opportunistic pathogens in premise plumbing: A review

Opportunistic premise (i.e., building) plumbing pathogens (OPPPs, e.g., Legionella pneumophila, Mycobacterium avium complex, Pseudomonas aeruginosa, Acanthamoeba, and Naegleria fowleri) are a significant and growing source of disease. Because OPPPs establish and grow as part of the native drinking water microbiota, they do not correspond to fecal indicators, presenting a major challenge to standard drinking water monitoring practices. Further, different OPPPs present distinct requirements for sampling, preservation, and analysis, creating an impediment to their parallel detection. The aim of this critical review is to evaluate the state of the science of monitoring OPPPs and identify a path forward for their parallel detection and quantification in a manner commensurate with the need for reliable data that is informative to risk assessment and mitigation. Water and biofilm sampling procedures, as well as factors influencing sample representativeness and detection sensitivity, are critically evaluated with respect to the five representative bacterial and amoebal OPPPs noted above. Available culturing and molecular approaches are discussed in terms of their advantages, limitations, and applicability. Knowledge gaps and research needs towards standardized approaches are identified.

Removals of cryptosporidium parvum oocysts and cryptosporidium-sized polystyrene microspheres from swimming pool water by diatomaceous earth filtration and perlite-sand filtration

Removal of Cryptosporidium-sized microspheres and Cryptosporidium parvum oocysts from swimming pools was investigated using diatomaceous earth (DE) precoat filtration and perlite-sand filtration. In pilot-scale experiments, microsphere removals of up to 2 log were obtained with 0.7 kg·DE/m² at a filtration rate of 5 m/h. A slightly higher microsphere removal (2.3 log) was obtained for these DE-precoated filters when the filtration rate was 3.6 m/h. Additionally, pilot-scale perlite-sand filters achieved greater than 2 log removal when at least 0.37 kg/m² of perlite was used compared to 0.1-0.4 log removal without perlite both at a surface loading rate of 37 m/h. Full-scale testing achieved 2.7 log of microspheres and oocysts removal when 0.7 kg·DE/m² was used at 3.6 m/h. Removals were significantly decreased by a 15-minute interruption of the flow (without any mechanical agitation) to the DE filter in pilot-scale studies, which was not observed in full-scale filters. Microsphere removals were 2.7 log by perlite-sand filtration in a full-scale swimming pool filter operated at 34 m/h with 0.5 kg/m² of perlite. The results demonstrate that either a DE precoat filter or a perlite-sand filter can improve the efficiency of removal of microspheres and oocysts from swimming pools over a standard sand filter under the conditions studied.

A large and persistent outbreak of typhoid fever caused by consuming contaminated water and street-vended beverages: Kampala, Uganda, January - June 2015

Background

On 6 February 2015, Kampala city authorities alerted the Ugandan Ministry of Health of a “strange disease” that killed one person and sickened dozens. We conducted an epidemiologic investigation to identify the nature of the disease, mode of transmission, and risk factors to inform timely and effective control measures.

Methods

We defined a suspected case as onset of fever (≥37.5 °C) for more than 3 days with abdominal pain, headache, negative malaria test or failed anti-malaria treatment, and at least 2 of the following: diarrhea, nausea or vomiting, constipation, fatigue. A probable case was defined as a suspected case with a positive TUBEX® TF test. A confirmed case had blood culture yielding Salmonella Typhi. We conducted a case-control study to compare exposures of 33 suspected case-patients and 78 controls, and tested water and juice samples.

Results

From 17 February–12 June, we identified 10,230 suspected, 1038 probable, and 51 confirmed cases. Approximately 22.58% (7/31) of case-patients and 2.56% (2/78) of controls drank water sold in small plastic bags (OR_M-H = 8.90; 95%CI = 1.60–49.00); 54.54% (18/33) of case-patients and 19.23% (15/78) of controls consumed locally-made drinks (OR_M-H = 4.60; 95%CI: 1.90–11.00). All isolates were susceptible to ciprofloxacin and ceftriaxone. Water and juice samples exhibited evidence of fecal contamination.

Conclusion

Contaminated water and street-vended beverages were likely vehicles of this outbreak. At our recommendation authorities closed unsafe water sources and supplied safe water to affected areas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-4002-0) contains supplementary material, which is available to authorized users.

Aggregation of Adenovirus 2 in Source Water and Impacts on Disinfection by Chlorine

It is generally accepted that viral particles in source water are likely to be found as aggregates attached to other particles. For this reason, it is important to investigate the disinfection efficacy of chlorine on aggregated viruses. A method to produce adenovirus particle aggregation was developed for this study. Negative stain electron microscopy was used to measure aggregation before and after addition of virus particles to surface water at different pH and specific conductance levels. The impact of aggregation on the efficacy of chlorine disinfection was also examined. Disinfection experiments with human adenovirus 2 (HAdV2) in source water were conducted using 0.2 mg/L free chlorine at 5 °C. Aggregation of HAdV2 in source water (≥3 aggregated particles) remained higher at higher specific conductance and pH levels. However, aggregation was highly variable, with the percentage of particles present in aggregates ranging from 43 to 71 %. Upon addition into source water, the aggregation percentage dropped dramatically. On average, chlorination CT values (chlorine concentration in mg/L × time in min) for 3-log10 inactivation of aggregated HAdV2 were up to three times higher than those for dispersed HAdV2, indicating that aggregation reduced the disinfection rate. This information can be used by water utilities and regulators to guide decision making regarding disinfection of viruses in water.

Use of Enterococcus faecalis and Bacillus atrophaeus as surrogates to establish and maintain laboratory proficiency for concentration of water samples using ultrafiltration

The U.S. Environmental Protection Agency's (EPA) Water Laboratory Alliance (WLA) currently uses ultrafiltration (UF) for concentration of biosafety level 3 (BSL-3) agents from large volumes (up to 100-L) of drinking water prior to analysis. Most UF procedures require comprehensive training and practice to achieve and maintain proficiency. As a result, there was a critical need to develop quality control (QC) criteria. Because select agents are difficult to work with and pose a significant safety hazard, QC criteria were developed using surrogates, including Enterococcus faecalis and Bacillus atrophaeus. This article presents the results from the QC criteria development study and results from a subsequent demonstration exercise in which E. faecalis was used to evaluate proficiency using UF to concentrate large volume drinking water samples. Based on preliminary testing EPA Method 1600 and Standard Methods 9218, for E. faecalis and B. atrophaeus respectively, were selected for use during the QC criteria development study. The QC criteria established for Method 1600 were used to assess laboratory performance during the demonstration exercise. Based on the results of the QC criteria study E. faecalis and B. atrophaeus can be used effectively to demonstrate and maintain proficiency using ultrafiltration.

Effect of cyanuric acid on the inactivation of Cryptosporidium parvum under hyperchlorination conditions

Cyanuric acid (CYA) is a chlorine stabilizer used in swimming pools to limit UV degradation of chlorine, thus reducing chlorine use and cost. However, CYA has been shown to decrease the efficacy of chlorine disinfection. In the event of a diarrheal incident, CDC recommends implementing 3-log10 inactivation conditions for Cryptosporidium (CT value = 15 300 mg·min/L) to remediate pools. Currently, CYA's impact on Cryptosporidium inactivation is not fully determined. We investigated the impact of multiple concentrations of CYA on C. parvum inactivation (at 20 and 40 mg/L free chlorine; average pH 7.6; 25 °C). At 20 mg/L free chlorine, average estimated 3-log10 CT values were 17 800 and 31 500 mg·min/L with 8 and 16 mg/L CYA, respectively, and the average estimated 1-log10 CT value was 76 500 mg·min/L with 48 mg/L CYA. At 40 mg/L free chlorine, 3-log10 CT values were lower than those at 20 mg/L, but still higher than those of free chlorine-only controls. In the presence of ∼100 mg/L CYA, average 0.8- and 1.4-log10 reductions were achieved by 72 h at 20 and 40 mg/L free chlorine, respectively. This study demonstrates CYA significantly delays chlorine inactivation of Cryptosporidium oocysts, emphasizing the need for additional pool remediation options following fecal incidents.

Development of a nucleic Acid extraction procedure for simultaneous recovery of DNA and RNA from diverse microbes in water

Drinking and environmental water samples contain a diverse array of constituents that can interfere with molecular testing techniques, especially when large volumes of water are concentrated to the small volumes needed for effective molecular analysis. In this study, a suite of enteric viruses, bacteria, and protozoan parasites were seeded into concentrated source water and finished drinking water samples, in order to investigate the relative performance of nucleic acid extraction techniques for molecular testing. Real-time PCR and reverse transcription-PCR crossing threshold (CT) values were used as the metrics for evaluating relative performance. Experimental results were used to develop a guanidinium isothiocyanate-based lysis buffer (UNEX buffer) that enabled effective simultaneous extraction and recovery of DNA and RNA from the suite of study microbes. Procedures for bead beating, nucleic acid purification, and PCR facilitation were also developed and integrated in the protocol. The final lysis buffer and sample preparation procedure was found to be effective for a panel of drinking water and source water concentrates when compared to commercial nucleic acid extraction kits. The UNEX buffer-based extraction protocol enabled PCR detection of six study microbes, in 100 L finished water samples from four drinking water treatment facilities, within three CT values (i.e., within 90% difference) of the reagent-grade water control. The results from this study indicate that this newly formulated lysis buffer and sample preparation procedure can be useful for standardized molecular testing of drinking and environmental waters.

Norovirus outbreak associated with a natural lake used for recreation - Oregon, 2014

In July 2014, Multnomah County public health officials investigated a norovirus outbreak among persons visiting Blue Lake Regional Park in Oregon. During the weekend of the reported illnesses (Friday, July 11-Sunday, July 13) approximately 15,400 persons visited the park. The investigation identified 65 probable and five laboratory-confirmed cases of norovirus infection (70 total cases). No hospitalizations or deaths were reported. Analyses from a retrospective cohort study revealed that swimming at Blue Lake during July 12-13 was significantly associated with illness during July 13-14 (adjusted relative risk = 2.3; 95% confidence interval [CI] = 1.1-64.9). Persons who swam were more than twice as likely to become ill compared with those who did not swim in the lake. To control the outbreak, Blue Lake was closed for 10 days to prevent further illness. This investigation underscores the need for guidance for determining when to reopen untreated recreational water venues (e.g., lakes) associated with outbreaks, and communication tools to inform the public about the risks associated with swimming in untreated recreational water venues and measures that can prevent illness.

Ascaris and Escherichia coli Inactivation in an Ecological Sanitation System in Port-au-Prince, Haiti

The goal of this study was to evaluate the microbial die-off in a latrine waste composting system in Port-au-Prince, Haiti. Temperature data and samples were collected from compost aged 0-12+ months. Samples collected from compost bin centers and corners at two depths were assessed for moisture content, E. coli concentration, and Ascaris spp. viability. Center temperatures in compost bins were all above 58 °C, while corner temperatures were 10 - 20 °C lower. Moisture content was 67 ± 10% in all except the oldest compost. A 4-log reduction in E. coli was observed over the first sixteen weeks of composting at both locations and depths, after which E. coli was undetectable (LOD: 142 MPN g(-1) dry weight). In new compost, 10.4% and 8.3% of Ascaris eggs were viable and fully embryonated, respectively. Percent viability dropped to zero in samples older than six weeks. These findings indicate that the Haitian EcoSan composting process was effective in inactivating E. coli and Ascaris spp. in latrine waste within sixteen weeks. This study is one of the first to document efficacy of an ecological sanitation system under field conditions and provides insight into composting methods and monitoring for other international settings.

Fate and transport of enteric microbes from septic systems in a coastal watershed

Onsite wastewater treatment systems (OWTS) are commonly used in coastal areas to treat household wastewater. These systems represent potential sources of fecal pollution of groundwater and nearby surface water. OWTS are expected to reduce microbial concentrations in wastewater; however, system and environmental factors can affect treatment efficiency and impacts on ground and surface water. In the study of OWTS described in this article, the authors sampled septic tanks and groundwater at two households in coastal North Carolina between October 2009 and October 2011. Samples were tested for the fecal indicator microbes E. coli, enterococci, and Clostridium perfringens. Microbial source tracking was also performed in year two. Results showed that enteric microbe concentrations in groundwater significantly decreased with distance from the OWTS. Human markers of fecal contamination were also detected in the OWTS and downgradient groundwater, indicating that OWTS can impact the microbial quality of shallow groundwater.

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.

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.

Relative insignificance of virus inactivation during aluminum electrocoagulation of saline waters

Combined removal and inactivation of the MS2 bacteriophage from model saline (0-100 mM NaCl) waters by electrochemical treatment using a sacrificial aluminum anode was evaluated. Both chemical and electrodissolution contributed to coagulant dosing since measured aluminum concentrations were statistically higher than purely electrochemical predictions using Faraday's law. Electrocoagulation generated only small amounts of free chlorine in situ but effectively destabilized viruses and incorporated them into Al(OH)3(s) flocs during electrolysis. Low chlorine concentrations combined with virus shielding and aggregation within flocs resulted in very slow disinfection rates necessitating extended flocculation/contact times to achieve significant log-inactivation. Therefore, the dominant virus control mechanism during aluminum electrocoagulation of saline waters is "physical" removal by uptake onto flocs rather than "chemical" inactivation by chlorine. Attenuated total reflectance-Fourier transform infrared spectroscopy provided evidence for oxidative transformations of capsid proteins including formation of oxyacids, aldehydes, and ketones. Electrocoagulation significantly altered protein secondary structures decreasing peak areas associated with turns, bends, α-helices, β-structures, and random coils for inactivated viruses compared with the MS2 stock. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) measurements showed rapid initial RNA damage following a similar trend as plaque assay measurements of infectious viruses. However, ssRNA cleavage measured by qRT-PCR underestimated inactivation over longer durations. Although aluminum electrocoagulation of saline waters disorders virus capsids and damages RNA, inactivation occurs at a sufficiently low rate so as to only play a secondary role to floc-encapsulation during residence times typical of electrochemical treatment.

Microbial and chemical contamination during and after flooding in the Ohio River-Kentucky, 2011

Surface water contaminants in Kentucky during and after 2011 flooding were characterized. Surface water samples were collected during flood stage (May 2-4, 2011; n = 15) and after (July 25-26, 2011; n = 8) from four different cities along the Ohio River and were analyzed for the presence of microbial indicators, pathogens, metals, and chemical contaminants. Contaminant concentrations during and after flooding were compared using linear and logistic regression. Surface water samples collected during flooding had higher levels of E. coli, enterococci, Salmonella, Campylobacter, E. coli O157:H7, adenovirus, arsenic, copper, iron, lead, and zinc compared to surface water samples collected 3-months post-flood (P < 0.05). These results suggest that flooding increases microbial and chemical loads in surface water. These findings reinforce commonly recommended guidelines to limit exposure to flood water and to appropriately sanitize contaminated surfaces and drinking wells after contamination by flood water.

Efficacy of chlorine dioxide tablets on inactivation of cryptosporidium oocysts

The ability of chlorine dioxide (ClO2) to achieve 2-log inactivation of Cryptosporidium in drinking water has been documented. No studies have specifically addressed the effects of ClO2 on C. parvum oocyst infectivity in chlorinated recreational water venues (e.g., pools). The aim of this research was to determine the efficacy of ClO2 as an alternative to existing hyperchlorination protocols that are used to achieve a 3-log inactivation of Cryptosporidium in such venues. To obtain a 3-log inactivation of C. parvum Iowa oocysts, contact times of 105 and 128 min for a solution containing 5 mg/L ClO2 with and without the addition of 2.6 mg/L free chlorine, respectively, were required. Contact times of 294 and 857 min for a solution containing 1.4 mg/L ClO2 with and without the addition of 3.6 mg/L free chlorine, respectively, were required. The hyperchlorination control (21 mg/L free chlorine only) required 455 min for a 3-log inactivation. Use of a solution containing 5 mg/L ClO2 and solutions containing 5 or 1.4 mg/L ClO2 with the addition of free chlorine appears to be a promising alternative to hyperchlorination for inactivating Cryptosporidium in chlorinated recreational water venues, but further studies are required to evaluate safety constraints on use.

A novel photoinduced electron transfer (PET) primer technique for rapid real-time PCR detection of Cryptosporidium spp

We report the development of a fluorescently labeled oligonucleotide primer that can be used to monitor real-time PCR. The primer has two parts, the 3'-end of the primer is complimentary to the target and a universal 17-mer stem loop at the 5'-end forms a hairpin structure. A fluorescent dye is attached to 5'-end of either the forward or reverse primer. The presence of guanosine residues at the first and second position of the 3' dangling end effectively quenches the fluorescence due to the photo electron transfer (PET) mechanism. During the synthesis of nucleic acid, the hairpin structure is linearized and the fluorescence of the incorporated primer increases several-fold due to release of the fluorescently labeled tail and the absence of guanosine quenching. As amplicons are synthesized during nucleic acid amplification, the fluorescence increase in the reaction mixture can be measured with commercially available real-time PCR instruments. In addition, a melting procedure can be performed to denature the double-stranded amplicons, thereby generating fluorescence peaks that can differentiate primer dimers and other non-specific amplicons if formed during the reaction. We demonstrated the application of PET-PCR for the rapid detection and quantification of Cryptosporidium parvum DNA. Comparison with a previously published TaqMan® assay demonstrated that the two real-time PCR assays exhibited similar sensitivity for a dynamic range of detection of 6000-0.6 oocysts per reaction. PET PCR primers are simple to design and less-expensive than dual-labeled probe PCR methods, and should be of interest for use by laboratories operating in resource-limited environments.

US outbreak of human Salmonella infections associated with aquatic frogs, 2008-2011

OBJECTIVE

Although amphibians are known Salmonella carriers, no such outbreaks have been reported. We investigated a nationwide outbreak of human Salmonella Typhimurium infections occurring predominantly among children from 2008 to 2011.

METHODS

We conducted a matched case-control study. Cases were defined as persons with Salmonella Typhimurium infection yielding an isolate indistinguishable from the outbreak strain. Controls were persons with recent infection with Salmonella strains other than the outbreak strain and matched to cases by age and geography. Environmental samples were obtained from patients' homes; traceback investigations were conducted.

RESULTS

We identified 376 cases from 44 states from January 1, 2008, to December 31, 2011; 29% (56/193) of patients were hospitalized and none died. Median patient age was 5 years (range <1-86 years); 69% were children <10 years old (253/367). Among 114 patients interviewed, 69 (61%) reported frog exposure. Of patients who knew frog type, 79% (44/56) reported African dwarf frogs (ADF), a type of aquatic frog. Among 18 cases and 29 controls, illness was significantly associated with frog exposure (67% cases versus 3% controls, matched odds ratio 12.4, 95% confidence interval 1.9-infinity). Environmental samples from aquariums containing ADFs in 8 patients' homes, 2 ADF distributors, and a day care center yielded isolates indistinguishable from the outbreak strain. Traceback investigations of ADFs from patient purchases converged to a common ADF breeding facility. Environmental samples from the breeding facility yielded the outbreak strain.

CONCLUSIONS

ADFs were the source of this nationwide pediatric predominant outbreak. Pediatricians should routinely inquire about pet ownership and advise families about illness risks associated with animals.

Preventing maritime transfer of toxigenic Vibrio cholerae

Organisms, including Vibrio cholerae, can be transferred between harbors in the ballast water of ships. Zones in the Caribbean region where distance from shore and water depth meet International Maritime Organization guidelines for ballast water exchange are extremely limited. Use of ballast water treatment systems could mitigate the risk for organism transfer.

Outbreak of cryptosporidiosis associated with a man-made chlorinated lake--Tarrant County, Texas, 2008

In July 2008, clusters of laboratory-confirmed cryptosporidiosis cases and reports of gastrointestinal illness in persons who visited a lake were reported to Tarrant County Public Health. In response, epidemiologic, laboratory, and environmental health investigations were initiated. A matched case-control study determined that swallowing the lake water was associated with illness (adjusted odds ratio = 16.3; 95% confidence interval: 2.5-infinity). The environmental health investigation narrowed down the potential sources of contamination. Laboratory testing detected Cryptosporidium hominis in case-patient stool specimens and Cryptosporidium species in lake water. It was only through the joint effort that epidemiologic, laboratory, and environmental health investigators could determine that >1 human diarrheal fecal incidents in the lake likely led to contamination of the water. This same collaborative effort will be needed to develop and maintain an effective national Model Aquatic Health Code.

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.

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.