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Recreational water-based cryptosporidiosis outbreaks doubled in 2 years
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Outbreaks of Cryptosporidium linked to recreational aquatic facilities in Alabama, Arizona, and Ohio have increased drastically, with twice as many outbreaks reported in 2016 compared with 2014, according to a recent study in MMWR.
Although most species of Cryptosporidium cannot be recognized through microscopy or immunoassays, the use of molecular surveillance through programs, such as CryptoNet, were able to identify species, subtype and chains of transmission, which the researchers noted may assist authorities in detecting outbreak sources and possible exposure.
“Since 2004, the annual incidence of nationally notified cryptosporidiosis has risen approximately threefold in the United States,” Michele C. Hlavsa, MPH, of the division of foodborne waterborne and environmental diseases at the National Center for Emerging and Zoonotic Infectious Diseases, CDC, and colleagues wrote. “Cryptosporidium also has emerged as the leading etiology of nationally notified recreational water-associated outbreaks, particularly those associated with aquatic facilities [such as] pools and support infrastructure.”
To emphasize specific outbreaks noted in Alabama, Arizona and Ohio, Hlavsa and colleagues used CryptoNet, the United States’ first molecular-based surveillance system for parasitic disease to clarify the parasite’s chain of transmission and epidemiology.
During a 2016 outbreak within Alabama, 35 people had acquired gastrointestinal symptoms after spending time at a local aquatic facility. Twenty-three cases were confirmed to be associated with this outbreak, and lab-confirmed Cryptosporidium was observed in three (13%) of these cases. Using CryptoNet and molecular characterization, officials could identify the specimen as C. hominis IfA12G1R5 subtype. Median incubation for this group was 8 days (5-17 days); however, few people completed a survey to verify the risk factors associated with this outbreak.
In this instance, fecal matter was not discovered in any aquatic venue. The facility was encouraged to develop policies concerning fecal incidents and keep a response log of all fecal and vomit incidents.
In Arizona, 36 of 51 (71%) little league players and their family members developed gastrointestinal symptoms 6 to 7 days after visiting an aquatic facility in July 2016. CryptoNet was used on four specimens collected. Molecular characterization determined that all four were infected with C. hominis IfAG12R5 subtype. Their local Department of Health noted increased lab reporting of cryptosporidiosis, and those patients went to the same facility as the little leaguers.
The venues within this county, which experienced 352 lab-confirmed cases of cryptosporidiosis between July and Oct. 2016, were instructed to hyperchlorinate. The outbreak was likely caused by the 43 people (17% of those interviewed) who reported swimming while having gastrointestinal symptoms.
The annual incidence of cryptosporidiosis was raised almost fivefold in 2016 within the state of Ohio. Time spent at aquatic venues contributed to 10 (42%) of the 24 reported outbreaks in this year, which resulted in 1,940 cases statewide. Six specimens were tested, and CrptoNet determined that all of the cases were caused by C. hominis IdA19 subtype, an unusual strain to be found within the U.S.
Five of the specimens were provided by members of a college sports team, which led the researchers to believe that the 26 cases of cryptosporidiosis observed in the university sports team were contributing factors to the waterpark-associated outbreak.
“Public health agencies and the aquatic sector need to collaborate on engaging swimmers, who are the source of contamination, in prevention efforts,” Hlavska and colleagues wrote. “Young swimmers aged younger than 5 years are more likely to contaminate the water because they are more likely to have inadequate toileting and hygiene skills; therefore, prevention efforts should focus on their parents.” — by Katherine Bortz
Disclosure: The researchers report no relevant financial disclosures.
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