There is no scientific evidence indicating that people can be chronically infected with West Nile virus. What remain in a person’s body for long periods of time are antibodies and “memory” white blood cells (T-lymphocytes) that the body produces to fight the virus. These antibodies and T-lymphocytes last for years, and may last for the rest of a person’s life. Antibodies are what many diagnostic tests look for when clinical laboratory testing is performed. Both antibodies and “memory” T-lymphocytes provide future protection from the virus.