October 13, 2017 – In late July of this year, the Nevada County Public Health Department began receiving reports of Shiga-toxin producing E. coli (STEC)-caused illnesses. These individual reports quickly evolved into an E. coli 0157:H7 outbreak that is associated with Lake Wildwood. As previously reported, there have been eighteen cases linked to this outbreak, ten of whom were hospitalized, and four of whom developed Hemolytic Uremic Syndrome (HUS). HUS is a severe, potentially life-threatening condition with anemia and kidney complications that can last throughout adulthood. HUS occurs in approximately 10% of those infected with E. coli 0157:H7.

In August and early September, Nevada County reported on elevated levels of fecal coliforms in the water of Lake Wildwood. In addition to the testing being done by the Nevada County Environmental Health Department (NCEHD), water and sediment samples were taken and sent to the Centers for Disease Control and Prevention (CDC) for more advanced testing to determine if a disease-associated STEC was present. CDC’s test results indicate that STEC O157, a potentially deadly pathogen, was identified both in the water at Meadow Park and in the submerged sediment at Commodore Beach. Their testing also showed that the STEC carried genetic markers from geese. In addition, STEC was isolated from a sample of goose scat near Meadow Park.

More recently Nevada County received additional test results from the California Department of Public Health. These results indicate that water samples taken from another part of the lake (near to where the Lake Wildwood Creek feeds into Lake Wildwood) tested positive for STEC 0157, but it appears to be unrelated to the outbreak strain. This means that two strains of a pathogen that can cause serious illness have now been identified in water and sediment samples taken from Lake Wildwood.

The environmental investigation continues to determine the source of contamination. Nevada County continues to work in consultation with state and federal colleagues on the investigation. In the meantime, for the purposes of public health and safety, the five public beaches at Lake Wildwood remain closed and the no-swim advisory is expanded to include any primary contact activities that could lead to the ingestion of lake water, such as water skiing.

For more information about E.coli, visit the California Department of Public Health’s website located at https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/E-coli-O157H7.aspx or visit the CDC’s website located at https://www.cdc.gov/ecoli/general/index.html.