The 49-year-old, one-time "Facts of Life" star revealed her medical condition via Twitter Tuesday.
"Dr. just called with blood test results ... I have West Nile. Ugh. I'm fine, just tired. Takes a year to recover," she wrote, adding she expects to make "a full recovery" and thanking fans for their support.
People.com said it is unclear whether her condition is related to her stint on "Survivor," which ended in April.