In the aftermath of the E. coli outbreak that affected 25 people in Virginia's Lake Anna, health officials have now issued a swimming advisory due to a harmful algae bloom. The Virginia Department of Health (VDH) has advised people to avoid contact with the upper section of the North Anna Branch of Lake Anna in Louisa County.

The presence of cyanobacteria, commonly known as blue-green algae, has been detected at unsafe levels in this section of the lake, located above Route 522. Exposure to cyanobacteria can cause skin rashes and gastrointestinal illnesses, including upset stomach, nausea, vomiting, and diarrhea.

VDH has urged individuals to refrain from activities that might result in ingesting water from the affected area. However, boating can continue with appropriate precautions. It is crucial to note that the harmful algae bloom is not linked to the recent E. coli outbreak, as the pathogen causing it is not associated with the bloom, according to the official release.

Margaret Smigo, the waterborne hazards program coordinator at VDH, explained that Lake Anna has a history of harmful algal blooms, which often occur during warmer weather and increased sunlight. Samples collected on Monday indicated slightly elevated concentrations of cyanotoxin, but below levels of concern for human health.

Addressing the duration of the advisory, Smigo stated that it generally takes approximately one month to lift such advisories, involving multiple samples taken ten days apart and extensive analysis and review processes.

Meanwhile, the 25 individuals affected by the Memorial Day weekend outbreak, including seven children, are still in the process of recovery. The VDH has ruled out food contamination, identifying the probable source of the E. coli outbreak as Lake Anna. However, pinpointing the exact source is challenging given the various illnesses reported during a holiday weekend with travel and potential exposure to recreational water.

VDH officials have conducted water tests which revealed fecal bacteria concentrations well below concerning levels on June 11 and Monday. Additional tests are planned for Tuesday. Smigo also mentioned that animals in the lake could have contributed to water contamination, but the timing of such an event remains uncertain. Weather conditions, particularly rainfall, could also carry pollutants into the lake.

When questioned about future swimming safety, Smigo emphasized the importance of assessing personal risk tolerance. Unlike swimming pools, natural water bodies don't have the same level of treatment and chlorine to reduce bacteria counts. Individuals with underlying health conditions, pregnant women, young children, and older individuals with weakened immune systems are advised to think twice before swimming in natural bodies of water.

As the harmful algae bloom compounds existing health concerns at Lake Anna, authorities are closely monitoring the situation and conducting regular tests to ensure the safety of residents and visitors.