Using Molecular Characterization to Support Investigations of Aquatic Facility–Associated Outbreaks of Cryptosporidiosis — Alabama, Arizona, and Ohio, 2016

Abstract

© 2017, Department of Health and Human Services. All rights reserved. What is already known about this topic? Cryptosporidium has emerged as the leading etiology of recreational water–associated outbreaks, particularly those associated with aquatic facilities (places that contain one or more aquatic venues [e.g., swimming pools, interactive water play venues or water playgrounds, or hot tubs/spas] and support infrastructure [e.g., chemical storage space]). What is added by this report? Most Cryptosporidium species are indistinguishable by traditional diagnostic tests (microscopy or immunoassays); only molecular diagnostic methods, such as those used by CryptoNet, the first U.S. molecularly based surveillance system for a parasitic disease, can distinguish these species and their subtypes. Given that individual Cryptosporidium species can have unique host ranges, identifying the Cryptosporidium species can provide insight into possible exposures and outbreak sources. In the summer of 2016, when detection of cryptosporidiosis outbreaks increased, CryptoNet supported outbreak investigations by further elucidating Cryptosporidium chains of transmission. What are the implications for public health practice? Regular analysis of molecular characterization and epidemiologic data through CryptoNet for each nationally notified cryptosporidiosis case can further elucidate Cryptosporidium chains of transmission and cryptosporidiosis epidemiology (e.g., by monitoring geographic and temporal changes in the distribution of Cryptosporidium species and their subtypes and associated exposures). CryptoNet data can then be used to optimize development of evidence-based prevention strategies. Not swimming when ill with diarrhea is key to preventing and controlling aquatic facility–associated cryptosporidiosis outbreaks (https://www.cdc.gov/healthywater/swimming/ swimmers/steps-healthy-swimming.html). State and local jurisdictions and aquatic facilities can voluntarily adopt recommendations in CDC’s Model Aquatic Health Code (https:// www.cdc.gov/mahc/editions/current.html) to prevent and control Cryptosporidium transmission in public aquatic venues.