The beach has been closed and access to the swimming area has been blocked off until the local health departments can confirm that the levels of fecal coliforms have fallen.
Dunn says her sister, the boy's mother, took him to Lake Wildwood Beach last week, where they went swimming near the clubhouse, a place the Nevada County Public Health Department now believes exposed him and four others to E. coli. HUS is a serious condition with anemia and kidney complications.
Since 2011, Cutler said, between one and six cases of E. coli-related illness per year have been reported in Nevada County. "However, some E. coli are pathogenic, meaning they can cause illness, either diarrhea or illness outside of the intestinal tract". The county says all of them had been swimming at Lake Wildwood beach near Grass Valley in Nevada County, KTLA sister station KTXL in Sacramento reported.
The Nevada County Environmental Health Department is now testing water samples from different locations around the lake.
According to the Nevada County Public Health Department, five children have gotten sick - three of them testing positive for E. coli.
"This illness is more risky in young children than healthy adults", a county press release quoted Cutler advising. In addition, Environmental Health Department staff worked with the Lake Wildwood Association to post warnings at all public beaches along the lake. The Environmental Health Department is expected to have more information Wednesday.
Health officials are now investigating possible sources of contamination.
There are wastewater treatment plants near the lake, but the county public works department said it found no leaks, and the system appears to be working normally.
The symptoms of Shiga toxin-producing E. coli include severe stomach cramps, diarrhea (often bloody), vomiting and sometimes fever. It can take up to ten days after exposure to develop symptoms, and most people recover within five to ten days. "This illness is more unsafe in young children than healthy adults", said Dr. Ken Cutler, Nevada County Health Officer. Moreover, anyone with symptoms or caring for someone should wash hands meticulously and frequently and not prepare food for others.