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Algal bloom-associated disease outbreaks among users of freshwater lakes-United States, 2009 - 2010
Citation:
Hilborn, E, V. Roberts, L. Backer, Tim Wade, J. Yoder, AND M. Hlavsa. Algal bloom-associated disease outbreaks among users of freshwater lakes-United States, 2009 - 2010. MORBIDITY AND MORTALITY WEEKLY REPORT. U.S. Department of Health and Human Services, Washington, DC, 63(1):11-25, (2014).
Impact/Purpose:
Outbreaks associated with freshwater algal blooms are uncommonly reported; only three have been previously reported via CDC's National Outbreak Reporting System. During the 2009 – 2010 reporting period, 11 outbreaks involving 61 persons occurred, and at least 67% of these individuals sought medical care for their illness. 66% of those affected were under the age of 19. This report represents a first attempt to summarize a group of algal bloom-associated outbreaks, however, much more work is needed to characterize these events.
Description:
‘Algal blooms’ are local abundances of phytoplankton – microscopic photosynthesizing aquatic organisms found in surface waters worldwide; blooms are variable temporally and spatially and frequently produce a visible algal scum on the water. Harmful algal blooms (HABs) are abundances of phytoplankton that produce biotoxins or otherwise adversely affect humans, animals and ecosystems. In fresh water, the cyanobacteria are common HABs; cyanotoxins include potent hepatotoxins, neurotoxins, and dermatotoxins (1). During 2009–2010, 11 waterborne disease outbreaks (WBDO) associated with algal blooms were voluntarily reported to CDC’s National Outbreak Reporting System (NORS); they represent 46% (11/24) of all untreated recreational WBDO reported during this time period, and 79% of all freshwater algal bloom-associated outbreaks ever reported to CDC’s WBDO surveillance system. These outbreaks occurred in three states and affected at least 61 people. Outbreak-associated health effects included gastrointestinal, dermatologic, respiratory and neurologic effects.