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On 3 February 2004, the Vermont Department of Health received reports of acute gastroenteritis in persons who had recently visited a swimming facility. A retrospective cohort study was conducted among persons attending the facility between 30 January and 2 February. Fifty-three of 189 (28%) persons interviewed developed vomiting or diarrhoea within 72 h after visiting the facility. Five specimens tested positive for norovirus and three specimen sequences were identical. Entering the smaller of the two pools at the facility was significantly associated with illness (RR 5.67, 95% CI 1.5-22.0, P=0.012). The investigation identified several maintenance system failures: chlorine equipment failure, poorly trained operators, inadequate maintenance checks, failure to alert management, and insufficient record keeping. This study demonstrates the vulnerability of recreational water to norovirus contamination, even in the absence of any obvious vomiting or faecal accident. Our findings also suggest that norovirus is not as resistant to chlorine as previously reported in experimental studies. Appropriate regulations and enforcement, with adequate staff training, are necessary to ensure recreational water safety. [ABSTRACT FROM AUTHOR]

Objectives: Chlorination destroys pathogens in swimming pool water, but by-products of chlorination can cause human illness. We investigated outbreaks of ocular and respiratory symptoms associated with chlorinated indoor swimming pools at two hotels.Measurements: We interviewed registered guests and companions who stayed at hotels X and Y within 2 days of outbreak onset. We performed bivariate and stratified analyses, calculated relative risks (RR) , and conducted environmental investigations of indoor pool areas.Results: Of 77 guests at hotel X, 47 (61%) completed questionnaires. Among persons exposed to the indoor pool area, 22 (71%) of 31 developed ocular symptoms [RR = 24; 95% confidence interval (CI), 1.5-370], and 14 (45%) developed respiratory symptoms (RR = 6.8; 95% CI, 1.0-47) with a median duration of 10 hr (0.25-24 hr) . We interviewed 30 (39%) of 77 registered persons and 59 unregistered companions at hotel Y. Among persons exposed to the indoor pool area, 41 (59%) of 69 developed ocular symptoms (RR = 24; 95% CI, 1.5-370), and 28 (41%) developed respiratory symptoms (RR = 17; 95% CI, 1.1-260) with a median duration of 2.5 hr (2 min-14 days). Four persons sought medical care. During the outbreak, the hotel X's ventilation system malfunctioned. Appropriate water and air samples were not available for laboratory analysis.Conclusions and relevance to professional practice: Indoor pool areas were associated with illness in these outbreaks. A large proportion of bathers were affected; symptoms were consistent with chloramine exposure and were sometimes severe. Improved staff training, pool maintenance, and pool area ventilation could prevent future outbreaks. [ABSTRACT FROM AUTHOR]

In August-September 2004, a cryptosporidiosis outbreak affected >250 persons who visited a California waterpark. Employees and patrons of the waterpark were affected, and three employees and 16 patrons admitted to going into recreational water while ill with diarrhoea. The median illness onset date for waterpark employees was 8 days earlier than that for patrons. A case-control study determined that getting water in one's mouth on the waterpark's waterslides was associated with illness (adjusted odds ratio 7.4, 95% confidence interval 1.7-32.2). Laboratory studies identified Cryptosporidium oocysts in sand and backwash from the waterslides' filter, and environmental investigations uncovered inadequate water-quality record keeping and a design flaw in one of the filtration systems. Occurring more than a decade after the first reported outbreaks of cryptosporidiosis in swimming pools, this outbreak demonstrates that messages about healthy swimming practices have not been adopted by pool operators and the public. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have collaboratively maintained the Waterborne Disease and Outbreak Surveillance System for collecting and reporting waterborne disease and outbreak (WBDO)-related data. In 1978, WBDOs associated with recreational water (natural and treated water) were added. This system is the primary source of data regarding the scope and effects of WBDOs in the United States.Reporting Period: Data presented summarize WBDOs associated with recreational water that occurred during January 2003--December 2004 and one previously unreported outbreak from 2002.Description of the System: Public health departments in the states, territories, localities, and the Freely Associated States (i.e., the Republic of the Marshall Islands, the Federated States of Micronesia, and the Republic of Palau, formerly parts of the U.S.-administered Trust Territory of the Pacific Islands) have primary responsibility for detecting, investigating, and voluntarily reporting WBDOs to CDC. Although the surveillance system includes data for WBDOs associated with drinking water, recreational water, and water not intended for drinking, only cases and outbreaks associated with recreational water are summarized in this report.Results: During 2003--2004, a total 62 WBDOs associated with recreational water were reported by 26 states and Guam. Illness occurred in 2,698 persons, resulting in 58 hospitalizations and one death. The median outbreak size was 14 persons (range: 1--617 persons). Of the 62 WBDOs, 30 (48.4%) were outbreaks of gastroenteritis that resulted from infectious agents, chemicals, or toxins; 13 (21.0%) were outbreaks of dermatitis; and seven (11.3%) were outbreaks of acute respiratory illness (ARI). The remaining 12 WBDOs resulted in primary amebic meningoencephalitis (n = one), meningitis (n = one), leptospirosis (n = one), otitis externa (n = one), and mixed illnesses (n = eight). WBDOs associated with gastroenteritis resulted in 1,945 (72.1%) of 2,698 illnesses. Forty-three (69.4%) WBDOs occurred at treated water venues, resulting in 2,446 (90.7%) cases of illness. The etiologic agent was confirmed in 44 (71.0%) of the 62 WBDOs, suspected in 15 (24.2%), and unidentified in three (4.8%). Twenty (32.3%) WBDOs had a bacterial etiology; 15 (24.2%), parasitic; six (9.7%), viral; and three (4.8%), chemical or toxin. Among the 30 gastroenteritis outbreaks, Cryptosporidium was confirmed as the causal agent in 11 (36.7%), and all except one of these outbreaks occurred in treated water venues where Cryptosporidium caused 55.6% (10/18) of the gastroenteritis outbreaks.In this report, 142 Vibrio illnesses (reported to the Cholera and Other Vibrio Illness Surveillance System) that were associated with recreational water exposure were analyzed separately. The most commonly reported species were Vibrio vulnificus, V. alginolyticus, and V. parahaemolyticus. V. vulnificus illnesses associated with recreational water exposure had the highest Vibrio illness hospitalization (87.2%) and mortality (12.8%) rates.Interpretation: The number of WBDOs summarized in this report and the trends in recreational water-associated disease and outbreaks are consistent with previous years. Outbreaks, especially the largest ones, are most likely to be associated with summer months, treated water venues, and gastrointestinal illness. Approximately 60% of illnesses reported for 2003--2004 were associated with the seven largest outbreaks (>100 cases). Deficiencies leading to WBDOs included problems with water quality, venue design, usage, and maintenance.Public Health Actions: CDC uses WBDO surveillance data to 1) identify the etiologic agents, types of aquatic venues, water-treatment systems, and deficiencies associated with outbreaks; 2) evaluate the adequacy of efforts (i.e., regulations and public awareness activities) to provide safe recreational water; and 3) establish public health prevention priorities that might lead to improved regulations and prevention measures at the local, state, and federal levels. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC, the U.S. Environmental Protection Agency (EPA), and the Council of State and Territorial Epidemiologists have maintained a collaborative Waterborne Disease and Outbreaks Surveillance System for collecting and reporting data related to occurrences and causes of waterborne disease and outbreaks (WBDOs). This surveillance system is the primary source of data concerning the scope and effects of WBDOs in the United States.Reporting Period: Data presented summarize 36 WBDOs that occurred during January 2003--December 2004 and nine previously unreported WBDOs that occurred during 1982--2002.Description of System: The surveillance system includes data on WBDOs associated with drinking water, water not intended for drinking (excluding recreational water), and water of unknown intent. Public health departments in the states, territories, localities, and Freely Associated States (i.e., the Republic of the Marshall Islands, the Federated States of Micronesia, and the Republic of Palau, formerly parts of the U.S.-administered Trust Territory of the Pacific Islands) are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC by using a standard form.Results: During 2003--2004, a total of 36 WBDOs were reported by 19 states; 30 were associated with drinking water, three were associated with water not intended for drinking, and three were associated with water of unknown intent. The 30 drinking water-associated WBDOs caused illness among an estimated 2,760 persons and were linked to four deaths. Etiologic agents were identified in 25 (83.3%) of these WBDOs: 17 (68.0%) involved pathogens (i.e., 13 bacterial, one parasitic, one viral, one mixed bacterial/parasitic, and one mixed bacterial/parasitic/viral), and eight (32.0%) involved chemical/toxin poisonings. Gastroenteritis represented 67.7% of the illness related to drinking water-associated WBDOs; acute respiratory illness represented 25.8%, and dermatitis represented 6.5%.The classification of deficiencies contributing to WBDOs has been revised to reflect the categories of concerns associated with contamination at or in the source water, treatment facility, or distribution system (SWTD) that are under the jurisdiction of water utilities, versus those at points not under the jurisdiction of a water utility or at the point of water use (NWU/POU), which includes commercially bottled water. A total of 33 deficiencies were cited in the 30 WBDOs associated with drinking water: 17 (51.5%) NWU/POU, 14 (42.4%) SWTD, and two (6.1%) unknown. The most frequently cited NWU/POU deficiencies involved Legionella spp. in the drinking water system (n = eight [47.1%]). The most frequently cited SWTD deficiencies were associated with distribution system contamination (n = six [42.9%]). Contaminated ground water was a contributing factor in seven times as many WBDOs (n = seven) as contaminated surface water (n = one).Interpretation: Approximately half (51.5%) of the drinking water deficiencies occurred outside the jurisdiction of a water utility in situations not currently regulated by EPA. The majority of the WBDOs in which deficiencies were not regulated by EPA were associated with Legionella spp. or chemicals/toxins. Problems in the distribution system were the most commonly identified deficiencies under the jurisdiction of a water utility, underscoring the importance of preventing contamination after water treatment. The substantial proportion of WBDOs involving contaminated ground water provides support for the Ground Water Rule (finalized in October 2006), which specifies when corrective action is required for public ground water systems.Public Health Actions: CDC and EPA use surveillance data to identify the types of water systems, deficiencies, and etiologic agents associated with WBDOs and to evaluate the adequacy of current technologies and practices for providing safe drinking water. Surveillance data also are used to establish research priorities, which can lead to improved water-quality regulation development. The growing proportion of drinking water deficiencies that are not addressed by current EPA rules emphasizes the need to address risk factors for water contamination in the distribution system and at points not under the jurisdiction of water utilities. [ABSTRACT FROM AUTHOR]

Problem/Condition: Cryptosporidiosis, a gastrointestinal illness, is caused by protozoa of the genus Cryptosporidium.Reporting Period: 1999--2002.System Description: State and two metropolitan health departments voluntarily reported cases of cryptosporidiosis through CDC's National Electronic Telecommunications System for Surveillance.Results: During 1999--2002, the total number of reported cases of cryptosporidiosis increased from 2,769 for 1999 to 3,787 for 2001 and then decreased to 3,016 for 2002. The number of states reporting cryptosporidiosis cases increased from 46 to 50, and the number of states reporting more than four cases per 100,000 population increased from two to five. A greater number of case reports were received for children aged 1--9 years and for adults aged 30--39 years compared with other age groups. Incidence of cryptosporidiosis was particularly high in the upper Midwest and Vermont. Peak onset of illness occurred annually during early summer through early fall.Interpretation: Transmission of cryptosporidiosis occurs throughout the United States, with increased diagnosis or reporting occurring in northern states. However, state incidence figures should be compared with caution because individual state surveillance systems have varying capabilities to detect cases. The seasonal peak in age-specific case reports coincides with the summer recreational water season and might reflect increased use of communal swimming venues (e.g., lakes, rivers, swimming pools, and water parks) by young children.Public Health Action: Cryptosporidiosis surveillance provides data to educate public health practitioners and health-care providers about the epidemiologic characteristics and the disease burden of cryptosporidiosis in the United States. These data are used to improve reporting of cases, plan prevention efforts, and establish research priorities. [ABSTRACT FROM AUTHOR]

Problem/Condition: Giardiasis, a gastrointestinal illness, is caused by the protozoan parasite Giardia intestinalis.Reporting Period: 1998--2002.System Description: State, commonwealth, territorial, and two metropolitan health departments voluntarily reported cases of giardiasis through CDC's National Electronic Telecommunications System for Surveillance.Results: During 1998--2002, the total number of reported cases of giardiasis decreased from 24,226 for 1998 to 19,708 for 2001 and then increased to 21,300 for 2002. The number of states reporting giardiasis cases increased from 42 to 46; however, the number of states reporting more than 15 cases per 100,000 population decreased from 10 to five. A greater number of case reports were received for children aged 1--9 years and for adults aged 30--39 years compared with other age groups. Incidence of giardiasis was highest in northern states. Peak onset of illness occurred annually during early summer through early fall.Interpretation: The increase observed for 2002 might reflect increased reporting after reporting of giardiasis as a nationally notifiable disease began in 2002. Transmission of giardiasis occurs throughout the United States, with increased diagnosis or reporting occurring in northern states. However, state incidence figures should be compared with caution because individual state surveillance systems have varying capabilities to detect cases. The seasonal peak in age-specific case reports coincides with the summer recreational water season and might reflect increased use of communal swimming venues (e.g., lakes, rivers, swimming pools, and water parks) by young children.Public Health Action: Giardiasis surveillance provides data to educate public health practitioners and health-care providers about the epidemiologic characteristics and the disease burden of giardiasis in the United States. These data are used to improve reporting of cases, plan prevention efforts, and establish research priorities. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have maintained a collaborative surveillance system for collecting and periodically reporting data related to occurrences and causes of waterborne-disease outbreaks (WBDOs). This surveillance system is the primary source of data concerning the scope and effects of waterborne disease outbreaks on persons in the United States.Reporting Period Covered: This summary includes data on WBDOs associated with drinking water that occurred during January 2001--December 2002 and on three previously unreported outbreaks that occurred during 2000.Description of the System: Public health departments in the states, territories, localities, and the Freely Associated States are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. The surveillance system includes data for outbreaks associated with both drinking water and recreational water; only outbreaks associated with drinking water are reported in this summary.Results: During 2001--2002, a total of 31 WBDOs associated with drinking water were reported by 19 states. These 31 outbreaks caused illness among an estimated 1,020 persons and were linked to seven deaths. The microbe or chemical that caused the outbreak was identified for 24 (77.4%) of the 31 outbreaks. Of the 24 identified outbreaks, 19 (79.2%) were associated with pathogens, and five (20.8%) were associated with acute chemical poisonings. Five outbreaks were caused by norovirus, five by parasites, and three by non-Legionella bacteria. All seven outbreaks involving acute gastrointestinal illness of unknown etiology were suspected of having an infectious cause. For the first time, this MMWR Surveillance Summary includes drinking water-associated outbreaks of Legionnaires disease (LD); six outbreaks of LD occurred during 2001--2002. Of the 25 non-Legionella associated outbreaks, 23 (92.0%) were reported in systems that used groundwater sources; nine (39.1%) of these 23 groundwater outbreaks were associated with private noncommunity wells that were not regulated by EPA.Interpretation: The number of drinking water-associated outbreaks decreased from 39 during 1999--2000 to 31 during 2001--2002. Two (8.0%) outbreaks associated with surface water occurred during 2001--2002; neither was associated with consumption of untreated water. The number of outbreaks associated with groundwater sources decreased from 28 during 1999--2000 to 23 during 2001--2002; however, the proportion of such outbreaks increased from 73.7% to 92.0%. The number of outbreaks associated with untreated groundwater decreased from 17 (44.7%) during 1999--2000 to 10 (40.0%) during 2001--2002. Outbreaks associated with private, unregulated wells remained relatively stable, although more outbreaks involving private, treated wells were reported during 2001--2002. Because the only groundwater systems that are required to disinfect their water supplies are public systems under the influence of surface water, these findings support EPA's development of a groundwater rule that specifies when corrective action (including disinfection) is required.Public Health Action: CDC and EPA use surveillance data 1) to identify the types of water systems, their deficiencies, and the etiologic agents associated with outbreaks and 2) to evaluate the adequacy of technologies for providing safe drinking water. Surveillance data are used also to establish research priorities, which can lead to improved water-quality regulations. CDC and EPA recently completed epidemiologic studies that assess the level of waterborne illness attributable to municipal drinking water in nonoutbreak conditions. The decrease in outbreaks in surface water systems is attributable primarily to implementation of provisions of EPA rules enacted since the late 1980s. Rules under development by EPA are expected to protect the public further from microbial contaminants while addressing risk tradeoffs of disinfection byproducts in drinking water. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have maintained a collaborative surveillance system for collecting and periodically reporting data related to occurrences and causes of waterborne-disease outbreaks (WBDOs) related to drinking water; tabulation of recreational water-associated outbreaks was added to the survillance system in 1978. This surveillance system is the primary source of data concerning the scope and effects of waterborne disease outbreaks on persons in the United States.Reporting Period Covered: This summary includes data on WBDOs associated with recreational water that occurred during January 2001--December 2002 and on a previously unreported outbreak that occurred during 1998.Description of the System: Public health departments in the states, territories, localities, and the Freely Associated States are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. The surveillance system includes data for outbreaks associated with both drinking water and recreational water; only outbreaks associated with recreational water are reported in this summary.Results: During 2001--2002, a total of 65 WBDOs associated with recreational water were reported by 23 states. These 65 outbreaks caused illness among an estimated 2,536 persons; 61 persons were hospitalized, eight of whom died. This is the largest number of recreational water-associated outbreaks to occur since reporting began in 1978; the number of recreational water-associated outbreaks has increased significantly during this period (p<0.01). Of these 65 outbreaks, 30 (46.2%) involved gastroenteritis. The etiologic agent was identified in 23 (76.7%) of these 30 outbreaks; 18 (60.0%) of the 30 were associated with swimming or wading pools. Eight (12.3%) of the 65 recreational water-associated disease outbreaks were attributed to single cases of primary amebic meningoencephalitis caused by Naegleria fowleri; all eight cases were fatal and were associated with swimming in a lake (n = seven; 87.5%) or river (n = one; 12.5%). Of the 65 outbreaks, 21 (32.3%) involved dermatitis; 20 (95.2%) of these 21 outbreaks were associated with spas or pools. In addition, one outbreak of Pontiac fever associated with a spa was reported to CDC. Four (6.1%) of the 65 outbreaks involved acute respiratory illness associated with chemical exposure at pools.Interpretation: The 30 outbreaks involving gastroenteritis comprised the largest proportion of recreational water-associated outbreaks during this reporting period. These outbreaks were associated most frequently with Cryptosporidium (50.0%) in treated water venues and with toxigenic Escherichia coli (25.0%) and norovirus (25.0%) in freshwater venues. The increase in the number of outbreaks since 1993 could reflect improved surveillance and reporting at the local and state level, a true increase in the number of WBDOs, or a combination of these factors.Public Health Action: CDC uses surveillance data to identify the etiologic agents, types of aquatics venues, water-treatment systems, and deficiencies associated with outbreaks and to evaluate the adequacy of efforts (e.g., regulations and public awareness activities) for providing safe recreational water. Surveillance data are also used to establish public health prevention priorities, which might lead to improved water-quality regulations at the local, state, and federal levels. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC, the U.S. Environmental Protection Agency (EPA), and the Council of State and Territorial Epidemiologists (CSTE) have maintained a collaborative surveillance system for the occurrences and causes of waterborne-disease outbreaks (WBDOs).This surveillance system is the primary source of data concerning the scope and effects of waterborne diseases on persons in the United States.Reporting Period Covered: This summary includes data regarding outbreaks occurring during January 1999--December 2000 and previously unreported outbreaks occurring in 1995 and 1997.Description of the System: The surveillance system includes data for outbreaks associated with drinking water and recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. The unit of analysis for the WBDO surveillance system is an outbreak, not an individual case of a waterborne disease. Two criteria must be met for an event to be defined as a WBDO. First, >2 persons must have experienced a similar illness after either ingestion of drinking water or exposure to water encountered in recreational or occupational settings. This criterion is waived for single cases of laboratory-confirmed primary amebic meningoencephalitis and for single cases of chemical poisoning if water-quality data indicate contamination by the chemical. Second, epidemiologic evidence must implicate water as the probable source of the illness.Results: During 1999--2000, a total of 39 outbreaks associated with drinking water was reported by 25 states. Included among these 39 outbreaks was one outbreak that spanned 10 states. These 39 outbreaks caused illness among an estimated 2,068 persons and were linked to two deaths. The microbe or chemical that caused the outbreak was identified for 22 (56.4%) of the 39 outbreaks; 20 of the 22 identified outbreaks were associated with pathogens, and two were associated with chemical poisoning. Of the 17 outbreaks involving acute gastroenteritis of unknown etiology, one was a suspected chemical poisoning, and the remaining 16 were suspected as having an infectious cause. Twenty-eight (71.8%) of 39 outbreaks were linked to groundwater sources; 18 (64.3%) of these 28 groundwater outbreaks were associated with private or noncommunity wells that were not regulated by EPA. Fifty-nine outbreaks from 23 states were attributed to recreational water exposure and affected an estimated 2,093 persons. Thirty-six (61.0%) of the 59 were outbreaks involving gastroenteritis. The etiologic agent was identified in 30 (83.3%) of 36 outbreaks involving gastroenteritis. Twenty-two (61.1%) of 36 gastroenteritis-related outbreaks were associated with pools or interactive fountains. Four (6.8%) of the 59 recreational water outbreaks were attributed to single cases of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri. All four cases were fatal. Fifteen (25.4%) of the 59 outbreaks were associated with dermatitis; 12 (80.0%) of 15 were associated with hot tubs or pools. In addition, recreational water outbreaks of leptospirosis, Pontiac fever, and chemical keratitis, as well as two outbreaks of leptospirosis and Pontiac fever associated with occupational exposure were also reported to CDC.Interpretation: The proportion of drinking water outbreaks associated with surface water increased from 11.8% during 1997--1998 to 17.9% in 1999--2000. The proportion of outbreaks (28) associated with groundwater sources increased 87% from the previous reporting period (15 outbreaks), and these outbreaks were primarily associated (60.7%) with consumption of untreated groundwater. Recreational water outbreaks involving gastroenteritis doubled (36 outbreaks) from the number of outbreaks reported in the previous reporting period (18 outbreaks). These outbreaks were most frequently associated with Cryptosporidium parvum (68.2%) in treated water venues (e.g., swimming pools or interactive fountains) and by Escherichia coli O157:H7 (21.4%) in freshwater venues. The increase in the number of outbreaks probably reflects improved surveillance and reporting at the local and state level as well as a true increase in the number of WBDOs.Public Health Action: CDC and others have used surveillance data to identify the types of water systems, their deficiencies, and the etiologic agents associated with outbreaks and evaluated current technologies for providing safe drinking water and safe recreational water. Surveillance data are used also to establish research priorities, which can lead to improved water-quality regulations. Only the groundwater systems under the influence of surface water are required to disinfect their water supplies, but EPA is developing a groundwater rule that specifies when corrective action (including disinfection) is required. CDC and EPA are conducting epidemiologic studies to assess the level of waterborne illness attributable to municipal drinking water in nonoutbreak conditions. Rules under development by EPA --- the Ground Water Rule (GWR), the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR), and Stage 2 Disinfection Byproduct Rules (DBPR) --- are expected to further protect the public from contaminants and disinfection byproducts in drinking water. Efforts by EPA under the Beaches Environmental Assessment, Closure, and Health (BEACH) program are aimed at reducing the risks for infection attributed to ambient recreational water by strengthening beach standards and testing; providing faster laboratory test methods; predicting pollution; investing in health and methods research; and improving public access to information regarding both the quality of the water at beaches and information concerning health risks associated with swimming in polluted water. EPA's Beach Watch (available at http://www.epa.gov/waterscience/beaches) provides online information regarding water quality at U.S. beaches, local protection programs, and other beach-related programs. CDC partnered with a consortium of local and national pool associations to develop a series of health communication materials for the general public who attend treated recreational water venues and to staff who work at those venues. CDC has also developed a recreational water outbreak investigation toolkit that can be used by public health professionals. All of the CDC materials are accessible at the CDC Healthy Swimming website (http://www.cdc.gov/healthyswimming). [ABSTRACT FROM AUTHOR]

Problem/Condition: Giardia intestinalis, the organism that causes the gastrointestinal illness giardiasis, is the most commonly diagnosed intestinal parasite in public health laboratories in the United States. In 1992, the Council of State and Territorial Epidemiologists assigned giardiasis an event code that enabled states to begin voluntarily reporting surveillance data on giardiasis to CDC. Reporting Period: This report includes data that were reported from January 1992 through December 1997. Description of the System: The National Giardiasis Surveillance System includes data about reported cases of giardiasis from participating states. Because most states were already collecting data on occurrence of giardiasis, the assignment of an event code to giardiasis has allowed voluntary reporting of these data to CDC via the National Electronic Telecommunications System for Surveillance. Results: Since 1992, the number of states reporting cases of giardiasis to CDC has risen from 23 to 43. The annual number of giardiasis cases reported has ranged from 12,793 in 1992 to 27,778 in 1996. In 1997, cases per 100,000 state population ranged from 0.9 to 42.3, with 10 states reporting >20.0 cases per 100,000 population and a national average of 9.5 cases per 100,000 population. In 1997, New York State, including New York City, reported the highest number of cases (3,673, or 20.3 cases per 100,000 population), accounting for 14.5% of cases nationally; however, Vermont reported the highest incidence rate in 1997 (42.3 cases per 100,000 population). Both states have active surveillance systems in place for giardiasis. Cases have an approximately equal sex distribution. Nationally, rates were the highest among children aged 0-5 years, followed closely by persons aged 31-40 years. In these two age groups, most cases were reported during late summer and early fall - an indication that transmission occurred during the summer. Interpretation: This report documents the first nationwide look at epidemiologic parameters and disease burden estimates for giardiasis in the United States. Transmission occurs in all major geographic areas of the country. The seasonal peak in age-specific case reports coincides with the summer recreational water season and might reflect the heavy use by young children of communal swimming venues (e.g., lakes, rivers, swimming pools, and water parks) - a finding consistent with Giardia's low infectious dose, the high prevalence of diaper-aged children in swimming venues, the extended periods of cyst shedding that can occur, and Giardia's environmental resistance. Estimates based on state surveillance data indicate that as many as 2.5 million cases of giardiasis occur annually in the United States. Public Health Action: Giardiasis surveillance provides data to educate public health practitioners and health-care providers about the scope and magnitude of giardiasis in the United States. These data can be used to establish research priorities and to plan future prevention efforts. [ABSTRACT FROM AUTHOR]

Problem/Condition: Since 1971, CDC and the U.S. Environmental Protection Agency (EPA) have maintained a collaborative surveillance system for collecting and periodically reporting data relating to occurrences and causes of waterborne-disease outbreaks (WBDOs). Reporting Period Covered: This summary includes data from January 1997 through December 1998 and a previously unreported outbreak in 1996. Description of the System: The surveillance system includes data regarding outbreaks associated with drinking water and recreational water. State, territorial, and local public health departments are primarily responsible for detecting and investigating WBDOs and voluntarily reporting them to CDC on a standard form. Results: During 1997-1998, a total of 13 states reported 17 outbreaks associated with drinking water. These outbreaks caused an estimated 2,038 persons to become ill. No deaths were reported. The microbe or chemical that caused the outbreak was identified for 12 (70.6%) of the 17 outbreaks; 15 (88.2%) were linked to groundwater sources. Thirty-two outbreaks from 18 states were attributed to recreational water exposure and affected an estimated 2,128 persons. Eighteen (56.3%) of the 32 were outbreaks of gastroenteritis, and 4 (12.5%) were single cases of primary amebic meningoencephalitis caused by Naegleria fowleri, all of which were fatal. The etiologic agent was identified for 29 (90.6%) of the 32 outbreaks, with one death associated with an Escherichia coli 0157:H7 outbreak. Ten (55.6%) of the 18 gastroenteritis outbreaks were associated with treated pools or ornamental fountains. Of the eight outbreaks of dermatitis, seven (87.5%) were associated with hot tubs, pools, or springs. Interpretation: Drinking water outbreaks associated with surface water decreased from 31.8% during 1995-1996 to 11.8% during 1997-1998. This reduction could be caused by efforts by the drinking water industry (e.g., Partnership for Safe Water), efforts by public health officials to improve drinking water quality, and improved water treatment afterthe implementation of EPA's Surface Water Treatment Rule. In contrast, the proportion of outbreaks associated with systems supplied by a groundwater source increased from 59.1% (i.e., 13) during 1995-1996 to 88.2% (i.e., 15) during 1997-1998. Outbreaks caused by parasites increased for both drinking and recreational water. All outbreaks of gastroenteritis attributed to parasites in recreational water were caused by Cryptosporidium, 90% occurred in treated water venues (e.g., swimming pools and decorative fountains), and fecal accidents were usually suspected. The data in this surveillance summary probably underestimate the true incidence of WBDOs because not all WBDOs are recognized, investigated, and reported to CDC or EPA. Actions Taken: To estimate the national prevalence of waterborne disease associated with drinking water, CDC and EPA are conducting a series of epidemiologic studies to better quantify the level of waterborne disease associated with drinking water in nonoutbreak conditions. The Information Collection Rule implemented by EPA in collaboration with the drinking water industry helped quantifythe level of pathogens in surface water. Efforts by CDC to address recreational water outbreaks have included meetings with the recreational water industry, focus groups to educate parents on prevention of waterborne disease transmission in recreational water settings, and publications with guidelines for parents and pool operators. [ABSTRACT FROM AUTHOR]

The article describes a communitywide cryptosporidiosis outbreak in Utah in 2007. Chlorine resistance and the need for control measures are discussed. The increase in cases in 2007 is reported to mirror the increase in outbreaks associated with treated recreational water such as pools and water parks. Recommendations for preventing outbreaks are listed including pre-outbreak planning, adoption of a disease action threshold and implementation of control measures if the threshold is exceeded. Data from the Utah Department of Health is included along with control measures and their effectiveness.

This article presents news from the U.S. Centers for Disease Control and Prevention (CDC). This study looked a cryptosporidiosis outbreaks associated with recreational water use in 5 U.S. states in 2006. An outbreak in Colorado reported from a water park is recounted. Two children in Illinois were infected at a day camp swimming pool, in Louisiana 35 cases were reported while South Carolina topped the list with 123 cases. Advice is offered for public health officials to reduce the risk for spreading the disease and the authors call for better water treatment in pools and water parks in the U.S.

This article presents news from the U.S. Centers for Disease Control and Prevention (CDC). The report looks at eye and respiratory illnesses associated with one indoor swimming pool in Nebraska in 2006. A child in that state was hospitalized in intensive care for severe chemical epiglottitis and laryngotracheobronchitis after swimming in a motel swimming pool. The pool was inspected the same day and closed for health code violations. An investigation found that 24 people became ill from swimming in that one pool and it is likely their illnesses resulted from toxic levels of chloramines that had accumulated in the air in the enclosed area.

Previous studies have recommended mandatory education for all public pool operators, but substantiating data are limited. This study evaluates associations between pool operator certification and chemistry violations by using 2005-2006 Nebraska routine pool inspection reports. Training and certification for nonmunicipal pool operators are only required in two Nebraska counties. Free chlorine violations for nonmunicipal pool inspections were compared in counties with and without certified operator requirements. To control for water supply pH, inspections from nonmunicipal pools with shared-source water in two counties (one requiring certification) were compared for concurrent pH and free chlorine violations. Compared with locations that require certified operators, free chlorine violations and concurrent pH and free chlorine violations were twice as likely in locations without certification. As a result, pools without required operator certification might pose greater health risks. These results demonstrate the benefit of requiring pool operator certification to help prevent recreational water illnesses. [ABSTRACT FROM AUTHOR]