The Virginia Department of Health has concluded its investigation into a Shiga toxin-producing Escherichia coli, or STEC, outbreak that occurred at Lake Anna over the Memorial Day holiday.
Water samples collected at Lake Anna did not detect the presence of STEC. Additional fecal bacteria results for the water samples did not show levels that are a public health concern.
It has been more than 20 days since the last person who visited the lake over the holiday became ill.
Five children required hospitalization after visiting Lake Anna. In total, there were 25 confirmed cases of STEC. There were five cases of hemolytic uremic syndrome, or HUS, reported in children, which can be serious.
Testing and risk
Laboratory testing by the Virginia Department of General Services Division of Consolidated Laboratory Services was not able to identify STEC O157 bacteria in water samples from the lake. VDH was not able to identify the source of the bacteria in the water.
The samples used for STEC testing were collected about four weeks after the Memorial Day weekend and might not reflect the water environment during the holiday weekend.
Swimming or other activities in any natural body of water always pose some health risk because the water is not disinfected. Children under the age of five years, older adults and those with weakened immune systems are at higher risk of contracting illness from natural bodies of water.
VDH and its local health departments will continue to work with local partners to better understand potential risks in the area and prevention strategies to address those risks.
The Department of Environmental Quality, or DEQ, will also continue the routine bacterial monitoring of Lake Anna that occurs each year between April and October.
Swimming advisory
The upper section of North Anna Branch of Lake Anna in Louisa County remains under a swimming advisory due to harmful algal blooms not related to this STEC outbreak.
VDH and the Virginia Harmful Algal Bloom Task Force will continue to monitor water quality in the lake for HAB. Advisories will be lifted following two consecutive test results with acceptable levels for algal cell counts and toxin concentration.
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Crystal Graham
