A statewide outbreak of Cryptosporidium and its association with the distribution of public swimming pools

Waterborne disease outbreaks in treated recreational water facilities: a Socio-Ecological Model perspective

Treated recreational water facilities, including swimming pools and water play parks, have often been implicated in infectious disease outbreaks. Addressing this problem is complex due to the multiple and interrelated factors contributing to outbreaks in these settings. These factors may relate to inappropriate behaviours of users and operators, lack of and inconsistent regulation of these facilities, insufficient facility maintenance, and problems associated with the design of these facilities. Given the complexity of this issue, we argue that the Socio-Ecological Model (SEM) provides a useful framework to help identify the multi-level influences and factors that have implications for designing interventions to prevent this public health problem, whilst assisting in guiding future research in this area. We apply the SEM to the current literature to help identify the influences and factors contributing to infectious disease outbreaks in treated recreational water facilities to support this argument. We also identify several gaps in the existing research that would benefit from further examination to help prevent infectious disease outbreaks in treated recreational water facilities such as public swimming pools and water play parks.

Preventing and controlling Cryptosporidium spp. in aquatic facilities: environmental health practitioners' experiences in Victoria, Australia

OBJECTIVE

To identify barriers and enablers to preventing and controlling Cryptosporidium spp. in aquatic facilities as perceived by environmental health practitioners (EHPs).

METHODS

A qualitative, constructivist study with a purposive sample of seven EHPs from Victoria, Australia, was conducted. A focus group discussion was guided by a semi-structured interview schedule using open-ended questions. The audio-recorded focus group was transcribed verbatim and analysed using thematic analysis.

RESULTS

Five themes represented the perceived barriers and enablers: i) pool water testing methods; ii) resources and training for EHPs; iii) knowledge and behaviour of aquatic facility operators and swimming pool users; iv) regulation; and v) aquatic facility and swimming pool design. Two key barriers within these themes included aquatic facility regulation and unhealthy swimming behaviours.

CONCLUSIONS

Several barriers and enablers to preventing and controlling Cryptosporidium spp. in aquatic facilities were perceived by EHPs. Suggestions to overcome perceived barriers were also identified. Further research is required to determine the impact of these findings on the incidence of cryptosporidiosis associated with aquatic facilities. Implications for public health: The findings contribute to a greater understanding of the barriers and enablers to Cryptosporidium spp. prevention and control in aquatic facilities, which may improve the effectiveness of current prevention and control strategies.

Limiting swimming pool outbreaks of cryptosporidiosis - the roles of regulations, staff, patrons and research

Cryptosporidium is the leading cause of swimming pool outbreaks of gastroenteritis. Transmission occurs through the ingestion of oocysts that are passed in the faeces of an infected person or animal when an accidental faecal release event occurs. Cryptosporidium parasites present specific challenges for infection control as oocysts are highly resistant to chlorine levels used for pool disinfection, infected individuals can shed large numbers of oocysts, there is a long incubation period and shedding of oocysts occurs even after symptom resolution. The purposes of this review are to identify key barriers to limiting swimming pool-associated outbreaks of cryptosporidiosis and to outline needs for research and collaboration to advance co-ordinated management practices. We reviewed swimming pool-associated cryptosporidiosis outbreaks, disinfection teachniques, current regulations and the role of staff and patrons. Key barriers to limiting swimming pool-associated outbreaks of cryptosporidiosis are a lack of uniform national and international standards, poor adherence and understanding of regulations governing staff and patron behaviour, and low levels of public knowledge and awareness.

The Risk of Reported Cryptosporidiosis in Children Aged <5 Years in Australia is Highest in Very Remote Regions

The incidence of cryptosporidiosis is highest in children <5 years, yet little is known about disease patterns across urban and rural areas of Australia. In this study, we examine whether the risk of reported cryptosporidiosis in children <5 years varies across an urban-rural gradient, after controlling for season and gender. Using Australian data on reported cryptosporidiosis from 2001 to 2012, we spatially linked disease data to an index of geographic remoteness to examine the geographic variation in cryptosporidiosis risk using negative binomial regression. The Incidence Risk Ratio (IRR) of reported cryptosporidiosis was higher in inner regional (IRR 1.4 95% CI 1.2–1.7, p < 0.001), and outer regional areas (IRR 2.4 95% CI 2.2–2.9, p < 0.001), and in remote (IRR 5.2 95% CI 4.3–6.2, p < 0.001) and very remote (IRR 8.2 95% CI 6.9–9.8, p < 0.001) areas, compared to major cities. A linear test for trend showed a statistically significant trend with increasing remoteness. Remote communities need to be a priority for future targeted health promotion and disease prevention interventions to reduce cryptosporidiosis in children <5 years.

Outbreak of Cryptosporidium hominis following river flooding in the city of Halle (Saale), Germany, August 2013

Background

During weeks 32–33, 2013, 24 cases of cryptosporidiosis were notified in the city of Halle (annual mean 2008–2012: 9 cases). We investigated the outbreak to identify the source and recommend control measures, considering that between weeks 23–25 the river Saale which flows through the city centre overflowed the floodplain, parts of the city centre and damaged sewage systems.

Methods

We defined a case as a resident of Halle with gastroenteritis, Cryptosporidium-positive stool and disease onset weeks 27 through 47. In a case–control study among kindergarten children, we compared cases and controls regarding environmental exposure, use of swimming pools, zoo visits and tap water consumption 14 days pre-onset or a corresponding 14-days-period (controls) and adjusted for residence. Stool specimens were tested by microscopy and PCR, and Cryptosporidium DNA was sequenced. Samples from public water system, swimming pools and river Saale were examined for Cryptosporidium oocysts (microscopy and PCR).

Results

Overall, 167 cases were detected, 40/167 (24%) were classified as secondary cases. First disease onsets occurred during week 29, numbers peaked in week 34 and started to decrease in week 36. Median age was 8 years (range: 0–77). Compared to controls (n = 61), cases (n = 20) were more likely to report visits to previously flooded areas (OR: 4.9; 95%-CI: 1.4-18) and the zoo (OR: 2.6; 95%-CI: 0.9-7.6). In multivariable analysis visits to the floodplain remained the sole risk factor (OR: 5.5; 95%-CI: 1.4-22). Only C.hominis of a single genotype (IbA9G2) was detected in stools. Oocysts were detected in samples from the river, two local lakes and three public swimming pools by microscopy, but not in the public water supply.

Conclusions

Evidence suggests that activities in the dried out floodplain led to infection among children. Secondary transmissions may be involved. Consequently, authorities recommended to avoid playing, swimming and having picnics in the flood-affected area. Health authorities should consider the potential health risks of long-term surviving parasites persisting on flooded grounds and in open waters even several weeks after the flooding and of bathing places close to sewage spill-overs. Preventive measures comprise water sampling (involving parasites), information of the public and prolonged closures of potentially contaminated sites.

Molecular diversity of Scottish Cryptosporidium hominis isolates

Cryptosporidium hominis is one of the most prevalent protozoan parasites to infect humans where transmission is via the consumption of infective oocysts. This study describes sporadic cases in addition to the molecular diversity of outbreak cases in Scotland using the glycoprotein-60 subtyping tool. From a total of 187 C. hominis isolates, 65 were subjected to further molecular analysis and 46 were found to be the common IbA10G2 subtype. Unusual subtypes included four isolates belonging to the Ia family (IaA14R3, n = 12; IaA14R2, n = 1; IaA9G3, n = 1; IaA25R3, n = 2), two from the Id family (IdA24, n = 1; IdA17, n = 1) and one belonging to the Ie family, namely IeA11G3T3. These data contribute significantly to our knowledge and understanding of the molecular diversity of C. hominis isolates from outbreak investigations involving Scottish residents which will be beneficial for the management of future outbreaks.

Investigation of a swimming pool-associated cryptosporidiosis outbreak in the Kimberley region of Western Australia

Cryptosporidiosis is a gastroenteric disease caused by the protozoan parasite Cryptosporidium, which manifests primarily as watery diarrhoea. Transmitted via the faecal–oral route, infection with the parasite can occur through ingestion of water, food or other fomites contaminated with its infective oocyst stage. In the months of November and December 2012, there were 18 notified cases of cryptosporidiosis from Broome, Western Australia. The 5-year average for the Kimberley region for this period is <1 case. Interviews conducted by Broome local government staff on the notified cases revealed that 11/18 cases had been swimming at the Broome public swimming pool. Molecular analyses of extracted DNA performed on 8/18 microscopy-positive faecal samples from interviewed cases and three water samples from different locations at the hypervariable glycoprotein 60 (gp60) gene, identified the C. hominis IbA10G2 subtype in all human samples and one water sample.

Cryptosporidium outbreaks associated with swimming pools

Acute gastrointestinal illness is a common and preventable public health issue. Exposure to recreational water, such as in swimming pools, is a risk factor for acute gastrointestinal illness. Serious outbreaks of water-borne diseases in Canada are rare but can pose a significant threat to human health. Cryptosporidium is one of the most common infectious agents causing pool-related outbreaks. Pool fouling, lack of education and training, inadequate pool structures, and lack of disinfection equipment have been linked to outbreaks of Cryptosporidium. To minimize the burden of swimming pool related outbreaks, interventions should include pool structure alterations, increased surveillance and reporting of swimming pool associated diseases, and public education regarding the risk of swimming pool infections.

Alternative indicators for monitoring Cryptosporidium oocysts in reclaimed water

With the widespread use of reclaimed water all over the world, there is a clear need to optimise its management in order to guarantee water safety. Model microorganisms (with either indicator or index function) are commonly used to assess risks related to the presence of enteric pathogens in water. Samples from five water reclamation plants located in Northeastern Spain were analysed to validate the use of three model microorganisms (Escherichia coli, somatic coliphages and spores of sulphite-reducing clostridia) as surrogates of Cryptosporidium total or infectious oocysts (TOO and IOO, respectively) in reclaimed water. Probability plots, simple and multiple linear regression and discriminant analyses were performed to assess their relationships. Results show that the detection of E. coli alone is not useful to model either the behaviour or concentrations of Cryptosporidium. However, discriminant analyses showed a high rate of correctly classified samples (91.9%) when E. coli and somatic coliphages data were used together to predict the presence/absence of IOO. Spores of sulphite-reducing clostridia (SRC) showed parallel reduction patterns and high correlation values (r = 0.76) with reductions in TOO. Furthermore, simple regression analyses of SRC and TOO in reclaimed water showed high correlation values (r = 0.85). Therefore, at the treatment plants studied, SRC can be considered to have good indicator and index functions for TOO. From the point of view of health protection, the use of SRC together with E. coli (which is mandatory in the current Spanish regulations) would satisfy the need for improved reclaimed water management.

Childhood parasitic infections endemic to the United States

Endemic parasitic infections in the United States are more frequent than is commonly perceived. Intestinal parasitic infection with Cryptosporidium, Dientamoeba, and Giardia occurs most often in children in northern states during the summer months. Zoonotic Toxocara and Toxoplasma parasitic infections are more frequent in southern states, in African Americans, and in populations with lower socioeconomic status. Approximately 300, 000 people in the United States have Trypanosoma cruzi infection. Local, vector-borne transmission of T cruzi and Leishmania infections has been documented in southern states. Parasitic diseases endemic to the United States are not uncommon but are understudied.