Pseudomonas Infection Outbreak Associated with a Hotel Swimming Pool - Maine, March 2023

Treated recreational water venues (e.g., pools and hot tubs) located at hotels represent one third of sources of reported treated recreational water-associated outbreaks; when these outbreaks are caused by Pseudomonas aeruginosa, they predominantly occur during January-April. On March 8, 2023, the Maine Center for Disease Control and Prevention (Maine CDC) initiated an investigation in response to reports of illness among persons who had used a swimming pool at hotel A during March 4-5. A questionnaire was distributed to guests who were at hotel A during March 1-7. Among 35 guests who responded, 23 (66%) developed ear pain, rash, or pain or swelling in feet or hands within days of using the pool during March 4-5. P. aeruginosa, a chlorine-susceptible bacterium, was identified in cultures obtained from skin lesions of three patients; a difference of two single nucleotide polymorphisms was found between isolates from two patients' specimens, suggesting a common exposure. Hotel A management voluntarily closed the pool, and Maine CDC's Health Inspection Program identified multiple violations, including having no disinfectant feeder system, all of which had been identified during a previous inspection. Because chlorine had been added to the pool water after the pool was voluntary closed, environmental samples were not collected. The pool remained closed until violations were addressed. Health departments can play an important role in reducing the risk for outbreaks associated with hotel pools and hot tubs. This reduction in risk can be achieved by collaborating with operators to ensure compliance with public health codes, including maintaining chlorine concentration and otherwise vigilantly managing the pool, and by disseminating prevention messages to pool and hot tub users.

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.

A Case of Primary Amebic Meningoencephalitis Associated with Surfing at an Artificial Surf Venue: Environmental Investigation

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. In September 2018, a 29-year-old man died of PAM after traveling to Texas. We conducted an epidemiologic and environmental investigation to identify the water exposure associated with this PAM case. The patient's most probable water exposure occurred while surfing in an artificial surf venue. The surf venue water was not filtered or recirculated; water disinfection and water quality testing were not documented. N. fowleri and thermophilic amebae were detected in recreational water and sediment samples throughout the facility. Codes and standards for treated recreational water venues open to the public could be developed to address these novel venues. Clinicians and public health officials should also consider novel recreational water venues as a potential exposure for this rare amebic infection.

Multiple introductions and recombination events underlie the emergence of a hyper-transmissible Cryptosporidium hominis subtype in the USA

The parasite Cryptosporidium hominis is a leading cause of the diarrheal disease cryptosporidiosis, whose incidence in the United States has increased since 2005. Here, we show that the newly emerged and hyper-transmissible subtype IfA12G1R5 is now dominant in the United States. In a comparative analysis of 127 newly sequenced and 95 published C. hominis genomes, IfA12G1R5 isolates from the United States place into three of the 14 clusters (Pop6, Pop13, and Pop14), indicating that this subtype has multiple ancestral origins. Pop6 (IfA12G1R5a) has an East Africa origin and has recombined with autochthonous subtypes after its arrival. Pop13 (IfA12G1R5b) is imported from Europe, where it has recombined with the prevalent local subtype, whereas Pop14 (IfA12G1R5c) is a progeny of secondary recombination between Pop6 and Pop13. Selective sweeps in invasion-associated genes have accompanied the emergence of the dominant Pop14. These observations offer insights into the emergence and evolution of hyper-transmissible pathogens.

Outbreaks Associated with Untreated Recreational Water - California, Maine, and Minnesota, 2018-2019

Outbreaks associated with fresh or marine (i.e., untreated) recreational water can be caused by pathogens or chemicals, including toxins. Voluntary reporting of these outbreaks to CDC's National Outbreak Reporting System (NORS) began in 2009. NORS data for 2009-2017 are finalized, and data for 2018-2019 are provisional. During 2009-2019 (as of May 13, 2020), public health officials from 31 states voluntarily reported 119 untreated recreational water-associated outbreaks, resulting at least 5,240 cases; 103 of the outbreaks (87%) started during June-August. Among the 119 outbreaks, 88 (74%) had confirmed etiologies. The leading etiologies were enteric pathogens: norovirus (19 [22%] outbreaks; 1,858 cases); Shiga toxin-producing Escherichia coli (STEC) (19 [22%]; 240), Cryptosporidium (17 [19%]; 237), and Shigella (14 [16%]; 713). This report highlights three examples of outbreaks that occurred during 2018-2019, were caused by leading etiologies (Shigella, norovirus, or STEC), and demonstrate the wide geographic distribution of such outbreaks across the United States. Detection and investigation of untreated recreational water-associated outbreaks are challenging, and the sources of these outbreaks often are not identified. Tools for controlling and preventing transmission of enteric pathogens through untreated recreational water include epidemiologic investigations, regular monitoring of water quality (i.e., testing for fecal indicator bacteria), microbial source tracking, and health policy and communications (e.g., observing beach closure signs and not swimming while ill with diarrhea).

Genotyping and Subtyping Cryptosporidium To Identify Risk Factors and Transmission Patterns - Nebraska, 2015-2017

Cryptosporidium is an enteric pathogen that is transmitted through animal-to-person or person-to-person contact or through ingestion of contaminated water or food. In the United States, Cryptosporidium affects an estimated 750,000 persons each year; however, only approximately 11,000 cases are reported nationally (1,2). Persons infected with Cryptosporidium typically develop symptoms within 2 to 10 days after exposure. Common symptoms include watery diarrhea, abdominal cramps, nausea, vomiting, or fever, which can last 1 to 2 weeks. Cryptosporidiosis is a nationally notifiable disease in the United States. Nebraska presents a unique setting for the evaluation of this pathogen because, compared with other states, Nebraska has a greater reliance on agriculture and a higher proportion of the population residing and working in rural communities. Cryptosporidium species and subtypes are generally indistinguishable using conventional diagnostic methods. Using molecular characterization, Nebraska evaluated the genetic diversity of Cryptosporidium and found a dichotomy in the distribution of cases of cryptosporidiosis caused by Cryptosporidium parvum and Cryptosporidium hominis among rural and urban settings. Characterizing clusters of C. hominis cases revealed that several child care facilities were affected by the same subtype, suggesting community-wide transmission and indicating a need for effective exclusion policies. Several cases of cryptosporidiosis caused by non-C. parvum or non-C. hominis species and genotypes indicated unique animal exposures that were previously unidentified. This study enhanced epidemiologic data by validating known Cryptosporidium sources, confirming outbreaks, and, through repeat interviews, providing additional information to inform cryptosporidiosis prevention and control efforts.

Prevention and Control of Youth Camp-Associated Acute Gastroenteritis Outbreaks

BACKGROUND

Approximately 14 million children attend more than 14000 US camps every year. Shared accommodations and activities can facilitate acute gastroenteritis (AGE) outbreaks.

METHODS

We analyzed data from the National Outbreak Reporting System on US youth camp-associated AGE outbreaks that occurred between 2009 and 2016. We also conducted a systematic literature search of youth camp-associated AGE outbreaks that have occurred around the world and a gray literature search for existing recommendations on outbreak prevention and control at camps worldwide.

RESULTS

Thirty-nine US jurisdictions reported a total of 229 youth camp-associated AGE outbreaks to the National Outbreak Reporting System. Of the 226 outbreaks included in our analyses, 120 (53%) were reported to have resulted from person-to-person transmission, 42 (19%) from an unknown transmission mode, 38 (17%) from foodborne transmission, 19 (8%) from waterborne transmission, 5 (2%) from animal contact, and 2 (<1%) from environmental contamination. Among 170 (75%) outbreaks with a single suspected or confirmed etiology, norovirus (107 [63%] outbreaks), Salmonella spp (16 [9%]), and Shiga-toxin producing Escherichia coli (12 [7%]) were implicated most frequently. We identified 43 additional youth camp-associated AGE outbreaks in the literature that occurred in various countries between 1938 and 2014. Control measures identified through the literature search included camp closure, separation of ill campers, environmental disinfection, and education on food preparation and hand hygiene.

CONCLUSIONS

Youth camp-associated AGE outbreaks are caused by numerous pathogens every year. These outbreaks are facilitated by factors that include improper food preparation, inadequate cleaning and disinfection, shared accommodations, and contact with animals. Health education focused on proper hygiene and preventing disease transmission could help control or prevent these outbreaks.

Case-case analyses of cryptosporidiosis and giardiasis using routine national surveillance data in the United States - 2005-2015

Understanding endemic infectious disease risk factors through traditional epidemiological tools is challenging. Population-based case-control studies are costly and time-consuming. A case-case analyses using surveillance data addresses these limitations by using resources more efficiently. We conducted a case-case analyses using routine surveillance data reported by 16 U.S. states (2005-2015), wherein reported cases of salmonellosis were used as a comparison group to identify exposure associations with reported cases of cryptosporidiosis and giardiasis. Odds ratios adjusted for age and reporting state (aOR) and 95% confidence intervals (95% CI) were calculated. A total of 10 704 cryptosporidiosis cases, 17 544 giardiasis cases, and 106 351 salmonellosis cases were included in this analyses. When compared with cases of salmonellosis, exposure to treated recreational water (aOR 4.7, 95% CI 4.3-5.0) and livestock (aOR: 3.2; 95% CI: 2.9-3.5) were significantly associated with cryptosporidiosis and exposure to untreated drinking (aOR 4.1, 95% CI 3.6-4.7) and recreational water (aOR 4.1, 95% CI 3.7-4.5) were associated with giardiasis. Our analyses shows that routine surveillance data with standardised exposure information can be used to identify associations of interest for cryptosporidiosis and giardiasis.

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.

Cryptosporidiosis Outbreak Associated With a Single Hotel

We investigated a gastrointestinal illness cluster among persons who attended a baseball tournament (>200 teams) during July 2015. We interviewed representatives of 19 teams; illness was reported among only the 9 (47%) teams that stayed at Hotel A (p < .01). We identified 55 primary cases. A case-control study demonstrated that pool exposure at Hotel A was significantly associated with illness (odds ratio: 7.3; 95% confidence interval: 3.6, 15.2). Eight out of nine (89%) stool specimens tested were positive for Cryptosporidium, with C. hominis IfA12G1 subtype identified in two specimens. The environmental health assessment detected a low free available chlorine level, and pool water tested positive for E. coli and total coliforms. A possible diarrheal contamination event, substantial hotel pool use, and use of cyanuric acid might have contributed to this outbreak and magnitude. Aquatic facilities practicing proper operation and maintenance (e.g., following the Centers for Disease Control and Prevention’s Model Aquatic Health Code) can protect the public’s health.

Immediate Closures and Violations Identified During Routine Inspections of Public Aquatic Facilities - Network for Aquatic Facility Inspection Surveillance, Five States, 2013

PROBLEM/CONDITION

Aquatic facility-associated illness and injury in the United States include disease outbreaks of infectious or chemical etiology, drowning, and pool chemical-associated health events (e.g., respiratory distress or burns). These conditions affect persons of all ages, particularly young children, and can lead to disability or even death. A total of 650 aquatic facility-associated outbreaks have been reported to CDC for 1978-2012. During 1999-2010, drownings resulted in approximately 4,000 deaths each year in the United States. Drowning is the leading cause of injury deaths in children aged 1-4 years, and approximately half of fatal drownings in this age group occur in swimming pools. During 2003-2012, pool chemical-associated health events resulted in an estimated 3,000-5,000 visits to U.S. emergency departments each year, and approximately half of the patients were aged <18 years. In August 2014, CDC released the Model Aquatic Health Code (MAHC), national guidance that can be adopted voluntarily by state and local jurisdictions to minimize the risk for illness and injury at public aquatic facilities.

REPORTING PERIOD COVERED

2013.

DESCRIPTION OF SYSTEM

The Network for Aquatic Facility Inspection Surveillance (NAFIS) was established by CDC in 2013. NAFIS receives aquatic facility inspection data collected by environmental health practitioners when assessing the operation and maintenance of public aquatic facilities. This report presents inspection data that were reported by 16 public health agencies in five states (Arizona, California, Florida, New York, and Texas) and focuses on 15 MAHC elements deemed critical to minimizing the risk for illness and injury associated with aquatic facilities (e.g., disinfection to prevent transmission of infectious pathogens, safety equipment to rescue distressed bathers, and pool chemical safety). Although these data (the first and most recent that are available) are not nationally representative, 15.7% of the estimated 309,000 U.S. public aquatic venues are located in the 16 reporting jurisdictions.

RESULTS

During 2013, environmental health practitioners in the 16 reporting NAFIS jurisdictions conducted 84,187 routine inspections of 48,632 public aquatic venues. Of the 84,187 routine inspection records for individual aquatic venues, 78.5% (66,098) included data on immediate closure; 12.3% (8,118) of routine inspections resulted in immediate closure because of at least one identified violation that represented a serious threat to public health. Disinfectant concentration violations were identified during 11.9% (7,662/64,580) of routine inspections, representing risk for aquatic facility-associated outbreaks of infectious etiology. Safety equipment violations were identified during 12.7% (7,845/61,648) of routine inspections, representing risk for drowning. Pool chemical safety violations were identified during 4.6% (471/10,264) of routine inspections, representing risk for pool chemical-associated health events.

INTERPRETATION

Routine inspections frequently resulted in immediate closure and identified violations of inspection items corresponding to 15 MAHC elements critical to protecting public health, highlighting the need to improve operation and maintenance of U.S. public aquatic facilities. These findings also underscore the public health function that code enforcement, conducted by environmental health practitioners, has in preventing illness and injury at public aquatic facilities.

PUBLIC HEALTH ACTION

Findings from the routine analyses of aquatic facility inspection data can inform program planning, implementation, and evaluation. At the state and local level, these inspection data can be used to identify aquatic facilities and venues in need of more frequent inspections and to select topics to cover in training for aquatic facility operators. At the national level, these data can be used to evaluate whether the adoption of MAHC elements minimizes the risk for aquatic facility-associated illness and injury. These findings also can be used to prioritize revisions or updates to the MAHC. To optimize the collection and analysis of aquatic facility inspection data and thus application of findings, environmental health practitioners and epidemiologists need to collaborate extensively to identify public aquatic facility code elements deemed critical to protecting public health and determine the best way to assess and document compliance during inspections.

Follow-up of the 1977 Georgia Outbreak of Toxoplasmosis

In 1977, an outbreak of toxoplasmosis occurred among 37 persons associated with exposure to an indoor horse arena. Cat feces containing the organism were most likely stirred up when horses ran on the dirt floor, and were inhaled or ingested by riders and observers. After 25 or more years, we attempted to locate persons from the outbreak and offer them an eye examination. Of the 37 persons in the outbreak, 18 (49%) were located; four had died, and the remaining 14 agreed to an examination. Among the 14 persons examined, three (21%) were found to have lesions typical of toxoplasmic retinochoroiditis. If these three persons were the only ones with ocular disease among the 37 persons in the outbreak, the disease rate would still be high (8%). As a result of exposure to Toxoplasma gondii during this outbreak, a relatively high percentage of persons developed ocular disease.

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.

Swimming in the USA: beachgoer characteristics and health outcomes at US marine and freshwater beaches

Swimming in lakes and oceans is popular, but little is known about the demographic characteristics, behaviors, and health risks of beachgoers on a national level. Data from a prospective cohort study of beachgoers at multiple marine and freshwater beaches in the USA were used to describe beachgoer characteristics and health outcomes for swimmers and non-swimmers. This analysis included 54,250 participants. Most (73.2%) entered the water; of those, 65.1% put their head under water, 41.3% got water in their mouth and 18.5% swallowed water. Overall, 16.3% of beachgoers reported any new health problem. Among swimmers, 6.6% reported gastrointestinal (GI) illness compared with 5.5% of non-swimmers (unadjusted χ² p < 0.001); 6.0% of swimmers and 4.9% of non-swimmers reported respiratory illness (p < 0.001); 1.8% of swimmers and 1.0% of non-swimmers reported ear problems (p < 0.001); and 3.9% of swimmers and 2.4% of non-swimmers experienced a rash (p < 0.001). Overall, swimmers reported a higher unadjusted incidence of GI illness and earaches than non-swimmers. Current surveillance systems might not detect individual cases and outbreaks of illness associated with swimming in natural water. Better knowledge of beachgoer characteristics, activities, and health risks associated with swimming in natural water can improve disease surveillance and prioritize limited resources.

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.

Cryptosporidiosis surveillance -- United States, 2011-2012

PROBLEM/CONDITION

Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by extremely chlorine-tolerant protozoa of the genus Cryptosporidium.

REPORTING PERIOD

2011-2012.

DESCRIPTION OF SYSTEM

Fifty state and two metropolitan public health agencies voluntarily report cases of cryptosporidiosis through CDC's National Notifiable Diseases Surveillance System.

RESULTS

For 2011, a total of 9,313 cryptosporidiosis cases (confirmed and nonconfirmed) were reported; for 2012, a total of 8,008 cases were reported; 5.8% and 5.3%, respectively, were associated with a detected outbreak. The rates of reported nonconfirmed cases were 1.0 and 0.9 per 100,000 population in 2011 and 2012, respectively, compared with an average of 0.0 during 1995-2004, and 0.3 during 2005-2010. The highest overall reporting rates were observed in the Midwest; 10 states reported >3.5 cases per 100,000 population in 2011 and in 2012. During 2011-2012, reported cases were highest among children aged 1-4 years (6.6 per 100,000 population), followed for the first time by elderly adults aged ≥80 years (3.4), and 75-79 years (3.3). Overall, cryptosporidiosis rates were higher among females than males during both years. For specific age groups, rates were higher among males than females aged <15 years and higher among females than males aged ≥15 years. Cryptosporidiosis symptom onset increased 4.4 fold during late summer.

INTERPRETATION

Cryptosporidiosis incidence rates remain elevated nationally, and rates of nonconfirmed cases have increased. Rates remain highest in young children, although rates among elderly adults are increasing. Transmission of Cryptosporidium occurs throughout the United States, with increased reporting occurring in Midwestern states. Seasonal onset peaks coincide with the summer recreational water season and might reflect increased use of communal swimming venues.

PUBLIC HEALTH ACTION

Future research is needed to address the evolving epidemiology of cryptosporidiosis cases, with a specific focus on the increase in nonconfirmed cases and increasing incidence rates among elderly adults. National systematic genotyping and subtyping of Cryptosporidium isolates could also help elucidate Cryptosporidium transmission and thus cryptosporidiosis epidemiology in the United States.

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.

Pool chemical-associated health events in public and residential settings - United States, 2003-2012, and Minnesota, 2013

Pool chemicals are added to treated recreational water venues (e.g., pools, hot tubs/spas, and interactive fountains) primarily to protect public health by inactivating pathogens and maximizing the effectiveness of disinfection by controlling pH. However, pool chemicals also can cause injuries when handled or stored improperly. To estimate the number of emergency department (ED) visits for injuries associated with pool chemicals in the United States per year during 2003-2012, CDC analyzed data from the U.S. Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS). This report summarizes the results of that analysis. In 2012 alone, an estimated 4,876 persons (95% confidence interval [CI] = 2,821-6,930) visited an ED for injuries associated with pool chemicals. Almost half of the patients were aged <18 years. This report also describes a pool chemical-associated health event that occurred in Minnesota in 2013, which sent seven children and one adult to an ED. An investigation by the Minnesota Department of Health (MDH) determined the cause to be poor monitoring of or response to pool chemistry. Pool chemical-associated health events are preventable. CDC's Model Aquatic Health Code (MAHC) (1) is a resource that state and local agencies can use to optimize prevention of injuries and illnesses associated with public treated recreational water venues, including pool chemical-associated health events.

Algal bloom-associated disease outbreaks among users of freshwater lakes--United States, 2009-2010

Harmful algal blooms (HABs) are excessive accumulations of microscopic photosynthesizing aquatic organisms (phytoplankton) that produce biotoxins or otherwise adversely affect humans, animals, and ecosystems. HABs occur sporadically and often produce a visible algal scum on the water. This report summarizes human health data and water sampling results voluntarily reported to CDC's Waterborne Disease and Outbreak Surveillance System (WBDOSS) via the National Outbreak Reporting System (NORS) and the Harmful Algal Bloom-Related Illness Surveillance System (HABISS)* for the years 2009-2010. For 2009-2010, 11 waterborne disease outbreaks associated with algal blooms were reported; these HABs all occurred in freshwater lakes. The outbreaks occurred in three states and affected at least 61 persons. Health effects included dermatologic, gastrointestinal, respiratory, and neurologic signs and symptoms. These 11 HAB-associated outbreaks represented 46% of the 24 outbreaks associated with untreated recreational water reported for 2009-2010, and 79% of the 14 freshwater HAB-associated outbreaks that have been reported to CDC since 1978. Clinicians should be aware of the potential for HAB-associated illness among patients with a history of exposure to freshwater.

Recreational water-associated disease outbreaks--United States, 2009-2010

Recreational water-associated disease outbreaks result from exposure to infectious pathogens or chemical agents in treated recreational water venues (e.g., pools and hot tubs or spas) or untreated recreational water venues (e.g., lakes and oceans). For 2009-2010, the most recent years for which finalized data are available, public health officials from 28 states and Puerto Rico electronically reported 81 recreational water-associated disease outbreaks to CDC's Waterborne Disease and Outbreak Surveillance System (WBDOSS) via the National Outbreak Reporting System (NORS). This report summarizes the characteristics of those outbreaks. Among the 57 outbreaks associated with treated recreational water, 24 (42%) were caused by Cryptosporidium. Among the 24 outbreaks associated with untreated recreational water, 11 (46%) were confirmed or suspected to have been caused by cyanobacterial toxins. In total, the 81 outbreaks resulted in at least 1,326 cases of illness and 62 hospitalizations; no deaths were reported. Laboratory and environmental data, in addition to epidemiologic data, can be used to direct and optimize the prevention and control of recreational water-associated disease outbreaks.

A survey of U.S. obstetrician-gynecologists' clinical and epidemiological knowledge of cryptosporidiosis in pregnancy

Although cryptosporidiosis is frequently diagnosed in the U.S., there has been very little assessment of obstetrician-gynaecologist knowledge about this disease. In 2010, we surveyed U.S. obstetricians about the diagnosis, treatment and epidemiology of cryptosporidiosis. Data were examined through univariable analysis and multivariable regression models. Of 1000 obstetrician-gynaecologists surveyed, 431 (43.1%) responded. Only 44.4% of respondents correctly identified that prolonged, intermittent diarrhoea would lead them to consider cryptosporidiosis in a differential diagnosis. Routine ova and parasites (O&P) testing was incorrectly chosen to identify Cryptosporidium in stool by 30.4% of respondents. Questions about nitazoxanide, the only drug approved by the U.S. Food & Drug Administration (FDA) for treatment of cryptosporidiosis, were the most frequently missed questions. Only 9.0% of respondents correctly classified nitazoxanide as an FDA pregnancy Category B drug, and only 5.6% of respondents correctly indicated that FDA approved nitazoxanide for immunocompetent patients aged ≥1 years. Regarding prevention- and control-related knowledge, only 14.1% of respondents correctly indicated that alcohol-based hand sanitizers were not effective at inactivating Cryptosporidium spp., and <10% correctly indicated that cryptosporidiosis is a reportable disease in their state of practice. Multivariable analysis found that ≥19 years in practice was positively associated with O&P diagnostic testing knowledge, while rural and urban non-inner city practice location, compared with suburban practice location, was positively associated with nitazoxanide knowledge. The low level of knowledge among obstetrician-gynaecologists about cryptosporidiosis indicates a need to develop resources for physicians about all aspects of cryptosporidiosis, particularly on diagnosis, treatment and prevention strategies.

Antimicrobial and analgesic prescribing patterns for acute otitis externa, 2004-2010

OBJECTIVE

Acute otitis externa (AOE) is a common but preventable ear condition. Clinical guidelines issued in 2006 recommended topical treatments for uncomplicated AOE, but systemic antimicrobials appear to be commonly prescribed. The objective of this analysis was to describe pre- and postguideline prescribing patterns by clinician specialty and antimicrobial type and assess trends over time.

STUDY DESIGN

Retrospective longitudinal analysis of a large insurance database.

SETTING

Outpatient departments in the United States.

METHODS

Initial outpatient visits in 2004 to 2010 for AOE (excluding visits with complicating conditions) were extracted from an insurance database. Prescription drug claims were linked and categorized by clinician specialty and antimicrobial type.

RESULTS

The analysis included 907,261 initial outpatient visits. Use of systemic antimicrobials declined by 4.9% (95% confidence interval [CI], 4.1%, 5.7%) from 36.5% of initial visits in 2004 to 32.1% in 2010. Use of systemic antimicrobials varied by specialty. Systemic antimicrobials were prescribed in 47.1% of 2010 emergency department (ED) visits (-6.9% from 2004, 95% CI -12.3, -1.5), 25.9% of otolaryngologist visits (-1.6%, 95% CI -5.6, 2.4), and 20.4% of pediatrician visits (-6.6%, 95% CI -8.8, -4.4). Penicillins were prescribed most frequently (42.3% of systemic prescriptions in 2010), followed by cephalosporins (19.8%), erythromycin/macrolides (17.4%), and quinolones (11.1%). Opioids were prescribed in 26.4% of ED visits and 9% of outpatient visits.

CONCLUSIONS

Use of systemic antimicrobials declined over time, but one-third of 2010 visits resulted in systemic antimicrobials, despite exclusion of visits with complicating factors. Use of systemic antimicrobials varied by specialty. Further educational efforts and outreach to other specialties might be warranted.

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.

Cryptosporidiosis surveillance--United States, 2009-2010

PROBLEM/CONDITION

Cryptosporidiosis is a nationally notifiable gastrointestinal illness caused by extremely chlorine-tolerant protozoa of the genus Cryptosporidium.

REPORTING PERIOD

2009-2010.

SYSTEM DESCRIPTION

Fifty state and two metropolitan public health agencies voluntarily report cases of cryptosporidiosis through CDC's National Notifiable Diseases Surveillance System.

RESULTS

For 2009, 7,656 confirmed and probable cases of cryptosporidiosis (2.5 per 100,000 population) were reported; for 2010, 8,951 confirmed and probable cases (2.9 per 100,000 population) were reported. All jurisdictions reported cryptosporidiosis cases for 2009-2010, and the number of jurisdictions reporting >3.5 cases per 100,000 population was 18 for 2009 and 20 for 2010. Cases were most frequently reported in children aged 1-9 years, followed by adults aged 25-29 years. This is the first reporting period in which more cases of cryptosporidiosis were reported in females than in males. Peak onset of illness occurred during early summer through early fall; the sympton onset of cases in children aged 5-9 years peaked earlier than that of cases reported in adults aged 25-34 years.

INTERPRETATION

Transmission of Cryptosporidium occurs throughout the United States. Rate data from reporting jurisdictions should be compared with caution because individual jurisdictions have varying capacities to detect, investigate, and report cases. The symptom onset and age-specific peaks coincide with the summer recreational water season and might reflect increased use of communal swimming venues (e.g., swimming pools and interactive fountains) by young children who then transmit the parasite to other users and their caregivers.

PUBLIC HEALTH ACTION

Local, state, and federal public health agencies can use cryptosporidiosis surveillance data to characterize the epidemiology of cryptosporidiosis in the United States, establish public health priorities (e.g., research) to improve cryptosporidiosis prevention and control, and design and evaluate efforts (e.g., health communication and policy) to prevent and control the transmission of Cryptosporidium.

Surveillance for waterborne disease outbreaks and other health events associated with recreational water --- United States, 2007--2008

PROBLEM/CONDITION

Since 1978, CDC, the U.S. Environmental Protection Agency, and the Council of State and Territorial Epidemiologists have collaborated on the Waterborne Disease and Outbreak Surveillance System (WBDOSS) for collecting and reporting data on waterborne disease outbreaks associated with recreational water. This surveillance system is the primary source of data concerning the scope and health effects of waterborne disease outbreaks in the United States. In addition, data are collected on other select recreational water--associated health events, including pool chemical--associated health events and single cases of Vibrio wound infection and primary amebic meningoencephalitis (PAM).

REPORTING PERIOD

Data presented summarize recreational water--associated outbreaks and other health events that occurred during January 2007--December 2008. Previously unreported data on outbreaks that have occurred since 1978 also are presented.

DESCRIPTION OF THE SYSTEM

The WBDOSS database includes data on outbreaks associated with recreational water, drinking water, water not intended for drinking (excluding recreational water), and water use of unknown intent. Public health agencies in the states, the District of Columbia, U.S. territories, and Freely Associated States are primarily responsible for detecting and investigating waterborne disease outbreaks and voluntarily reporting them to CDC using a standard form. Only data on outbreaks associated with recreational water are summarized in this report. Data on other recreational water--associated health events reported to CDC, the Agency for Toxic Substances and Disease Registry (ATSDR), and the U.S. Consumer Product Safety Commission (CPSC) also are summarized.

RESULTS

A total of 134 recreational water--associated outbreaks were reported by 38 states and Puerto Rico for 2007--2008. These outbreaks resulted in at least 13,966 cases. The median outbreak size was 11 cases (range: 2--5,697 cases). A total of 116 (86.6%) outbreaks were associated with treated recreational water (e.g., pools and interactive fountains) and resulted in 13,480 (96.5%) cases. Of the 134 outbreaks, 81 (60.4%) were outbreaks of acute gastrointestinal illness (AGI); 24 (17.9%) were outbreaks of dermatologic illnesses, conditions, or symptoms; and 17 (12.7%) were outbreaks of acute respiratory illness. Outbreaks of AGI resulted in 12,477 (89.3%) cases. The etiology was laboratory-confirmed for 105 (78.4%) of the 134 outbreaks. Of the 105 outbreaks with a laboratory-confirmed etiology, 68 (64.8%) were caused by parasites, 22 (21.0%) by bacteria, five (4.8%) by viruses, nine (8.6%) by chemicals or toxins, and one (1.0%) by multiple etiology types. Cryptosporidium was confirmed as the etiologic agent of 60 (44.8%) of 134 outbreaks, resulting in 12,154 (87.0%) cases; 58 (96.7%) of these outbreaks, resulting in a total of 12,137 (99.9%) cases, were associated with treated recreational water. A total of 32 pool chemical--associated health events that occurred in a public or residential setting were reported to WBDOSS by Maryland and Michigan. These events resulted in 48 cases of illness or injury; 26 (81.3%) events could be attributed at least partially to chemical handling errors (e.g., mixing incompatible chemicals). ATSDR's Hazardous Substance Emergency Events Surveillance System received 92 reports of hazardous substance events that occurred at aquatic facilities. More than half of these events (55 [59.8%]) involved injured persons; the most frequently reported primary contributing factor was human error. Estimates based on CPSC's National Electronic Injury Surveillance System (NEISS) data indicate that 4,574 (95% confidence interval [CI]: 2,703--6,446) emergency department (ED) visits attributable to pool chemical--associated injuries occurred in 2008; the most frequent diagnosis was poisoning (1,784 ED visits [95% CI: 585--2,984]). NEISS data indicate that pool chemical--associated health events occur frequently in residential settings. A total of 236 Vibrio wound infections were reported to be associated with recreational water exposure; 36 (48.6%) of the 74 hospitalized vibriosis patients and six (66.7%) of the nine vibriosis patients who died had V. vulnificus infections. Eight fatal cases of PAM occurred after exposure to warm untreated freshwater.

INTERPRETATIONS

The 134 recreational water--associated outbreaks reported for 2007--2008 represent a substantial increase over the 78 outbreaks reported for 2005--2006 and the largest number of outbreaks ever reported to WBDOSS for a 2-year period. Outbreaks, especially the largest ones, were most frequently associated with treated recreational water and characterized by AGI. Cryptosporidium remains the leading etiologic agent. Pool chemical--associated health events occur frequently but are preventable. Data on other select recreational water--associated health events further elucidate the epidemiology of U.S. waterborne disease by highlighting less frequently implicated types of recreational water (e.g., oceans) and detected types of recreational water--associated illness (i.e., not AGI).

PUBLIC HEALTH ACTIONS

CDC uses waterborne disease outbreak surveillance data to 1) identify the types of etiologic agents, recreational water venues, and settings associated with waterborne disease outbreaks; 2) evaluate the adequacy of regulations and public awareness activities to promote healthy and safe swimming; and 3) establish public health priorities to improve prevention efforts, guidelines, and regulations at the local, state, and federal levels.

Surveillance for waterborne disease and outbreaks associated with recreational water use and other aquatic facility-associated health events--United States, 2005-2006

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 data related to waterborne-disease outbreaks (WBDOs) associated with drinking water. 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 disease associated with recreational water in the United States. In addition, data are collected on individual cases of recreational water-associated illnesses and infections and health events occurring at aquatic facilities but not directly related to water exposure.

REPORTING PERIOD

Data presented summarize WBDOs and case reports associated with recreational water use that occurred during January 2005--December 2006 and previously unreported disease reports and outbreaks during 1978--2004.

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 and cases associated with drinking water, recreational water, and water not intended for drinking, only cases and outbreaks associated with recreational water and health events at aquatic facilities are summarized in this report.

RESULTS

During 2005--2006, a total of 78 WBDOs associated with recreational water were reported by 31 states. Illness occurred in 4,412 persons, resulting in 116 hospitalizations and five deaths. The median outbreak size was 13 persons (range: 2--2,307 persons). Of the 78 WBDOs, 48 (61.5%) were outbreaks of gastroenteritis that resulted from infectious agents or chemicals; 11 (14.1%) were outbreaks of acute respiratory illness; and 11 (14.1%) were outbreaks of dermatitis or other skin conditions. The remaining eight were outbreaks of leptospirosis (n = two), primary amebic meningoencephalitis (n = one), and mixed or other illnesses (n = five). WBDOs associated with gastroenteritis resulted in 4,015 (91.0%) of 4,412 illnesses. Fifty-eight (74.4%) WBDOs occurred at treated water venues, resulting in 4,167 (94.4%) cases of illness. The etiologic agent was confirmed in 62 (79.5%) of the 78 WBDOs, suspected in 12 (15.4%), and unidentified in four (5.1%). Thirty-four (43.6%) WBDOs had a parasitic etiology; 22 (28.2%), bacterial; four (5.1%), viral; and two (2.6%), chemical or toxin. Among the 48 gastroenteritis outbreaks, Cryptosporidium was confirmed as the causal agent in 31 (64.6%), and all except two of these outbreaks occurred in treated water venues where Cryptosporidium caused 82.9% (29/35) of the gastroenteritis outbreaks. Case reports associated with recreational water exposure that were discussed and analyzed separately from outbreaks include three fatal Naegleria cases and 189 Vibrio illnesses reported to the Cholera and Other Vibrio Illness Surveillance System. For Vibrio reporting, 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 (77.6%) and mortality (22.4%) rates. In addition, 32 aquatic facility-related health events not associated with recreational water use (e.g., pool chemical mixing accidents) that occurred during 1983--2006 were received from New York. These events, which caused illness in 364 persons, are included in this report but analyzed separately.

INTERPRETATIONS

The number of WBDOs summarized in this report and the trends in recreational water-associated disease and outbreaks demonstrate a substantial increase in number of reports from previous years. Outbreaks, especially the largest ones, occurred more frequently in the summer at treated water venues and caused gastrointestinal illness. Deficiencies leading to WBDOs included problems with water-quality, venue design, usage, and maintenance. Case reports of illness associated with recreational water use expand our understanding of the scope of waterborne illness by further underscoring the contribution of less well-recognized swimming venues (e.g., oceans) and illness (e.g., nongastrointestinal illness). Aquatic facilities are also a focus for injuries involving chemicals or equipment used routinely in the operation of swimming venues, thus illustrating the lack of training of some aquatics staff.

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 and case reports; 2) evaluate the adequacy of efforts (i.e., regulations and public awareness activities) to provide safe recreational water; 3) expand the scope of understanding about waterborne disease and health events associated with swimming and aquatics facilities; and 4) establish public health prevention priorities, data, and messaging that might lead to improved regulations, guidelines, and prevention measures at the local, state, and federal levels.

Surveillance for waterborne disease and outbreaks associated with drinking water and water not intended for drinking--United States, 2005-2006

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 Outbreak Surveillance System (WBDOSS) for collecting and reporting data related to occurrences and causes of waterborne-disease outbreaks (WBDOs) and cases of waterborne disease. This surveillance system is the primary source of data concerning the scope and effects of waterborne disease in the United States.

REPORTING PERIOD

Data presented summarize 28 WBDOs that occurred during January 2005--December 2006 and four previously unreported WBDOs that occurred during 1979--2002.

DESCRIPTION OF SYSTEM

The surveillance system includes data on WBDOs associated with recreational water, drinking water, water not intended for drinking (WNID) (excluding recreational water), and water use of unknown intent. Public health departments in the states, territories, localities, and Freely Associated States (FAS) (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 a standard form. Only cases and outbreaks associated with drinking water, WNID (excluding recreational water), and water of unknown intent (WUI) are summarized in this report. Cases and outbreaks associated with recreational water are reported in a separate Surveillance Summary.

RESULTS

Fourteen states reported 28 WBDOs that occurred during 2005--2006: a total of 20 were associated with drinking water, six were associated with WNID, and two were associated with WUI. The 20 drinking water-associated WBDOs caused illness among an estimated 612 persons and were linked to four deaths. Etiologic agents were identified in 18 (90.0%) of the drinking water-associated WBDOs. Among the 18 WBDOs with identified pathogens, 12 (66.7%) were associated with bacteria, three (16.7%) with viruses, two (11.1%) with parasites, and one (5.6%) mixed WBDO with both bacteria and viruses. In both WBDOs where the etiology was not determined, norovirus was the suspected etiology. Of the 20 drinking water WBDOs, 10 (50) were outbreaks of acute respiratory illness (ARI), nine (45%) were outbreaks of acute gastrointestinal illness (AGI), and one (5.0%) was an outbreak of hepatitis. All WBDOs of ARI were caused by Legionella, and this is the first reporting period in which the proportion of ARI WBDOs has surpassed that of AGI WBDOs since the reporting of Legionella WBDOs was initiated in 2001. A total of 23 deficiencies were cited in the 20 WBDOs associated with drinking water: 12 (52.2%) deficiencies fell under the classification NWU/POU (deficiencies occurred at points not under the jurisdiction of a water utility or at the point-of-use), 10 (43.5%) deficiencies fell under the classification SWTDs (contamination at or in the source water, treatment facility, or distribution system), and for one (4.3%) deficiency, classification was unknown. Among the 12 NWU/POU deficiencies, 10 (83.3%) involved Legionella spp. in the drinking water system. The most frequently cited SWTD deficiencies were associated with a treatment deficiency (n = four [40.0%]) and untreated ground water (n = four [40.0%]). Three of the four WBDOs with treatment deficiencies used ground water sources.

INTERPRETATION

Approximately half (52.2%) of the drinking water deficiencies occurred outside the jurisdiction of a water utility. The majority of these WBDOs were associated with Legionella spp, which suggests that increased attention should be targeted towards reducing illness risks associated with Legionella spp. Nearly all of WBDOs associated with SWTD deficiencies occurred in systems using ground water. EPA's new Ground Water Rule might prevent similar outbreaks in the future in public 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 majority of drinking water deficiencies are now associated with contamination at points outside the jurisdiction of public water systems (e.g., regrowth of Legionella spp. in hot water systems) and water contamination that might not be regulated by EPA (e.g., contamination of tap water at the POU). Improved education of consumers and plumbers might help address these risk factors.

Human tuberculosis due to Mycobacterium bovis in the United States, 1995-2005

BACKGROUND

Understanding the epidemiology of human Mycobacterium bovis tuberculosis (TB) in the United States is imperative; this disease can be foodborne or airborne, and current US control strategies are focused on TB due to Mycobacterium tuberculosis and airborne transmission. The National TB Genotyping Service's work has allowed systematic identification of M. tuberculosis-complex isolates and enabled the first US-wide study of M. bovis TB.

METHODS

Results of spacer oligonucleotide and mycobacterial interspersed repetitive units typing were linked to corresponding national surveillance data for TB cases reported for the period 2004-2005 and select cases for the period 1995-2003. We also used National TB Genotyping Service data to evaluate the traditional antituberculous drug resistance-based case definition of M. bovis TB.

RESULTS

Isolates from 165 (1.4%) of 11,860 linked cases were identified as M. bovis. Patients who were not born in the United States, Hispanic patients, patients <15 years of age, patients reported to be HIV infected, and patients with extrapulmonary disease each had increased adjusted odds of having M. bovis versus M. tuberculosis TB. Most US-born, Hispanic patients with TB due to M. bovis (29 [90.6%] of 32) had extrapulmonary disease, and their overall median age was 9.5 years. The National TB Genotyping Service's data indicated that the pyrazinamide-based case definition's sensitivity was 82.5% (95% confidence interval; 75.3%-87.9%) and that data identified 14 errors in pyrazinamide-susceptibility testing or reporting.

CONCLUSIONS

The prevalence of extrapulmonary disease in the young, US-born Hispanic population suggests recent transmission of M. bovis, possibly related to foodborne exposure. Because of its significantly different epidemiologic profile, compared with that of M. tuberculosis TB, we recommend routine surveillance of M. bovis TB. Routine surveillance and an improved understanding of M. bovis TB transmission dynamics would help direct the development of additional control measures.

Cryptosporidiosis surveillance--United States 1999-2002

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.

Giardiasis surveillance--United States, 1998-2002

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.