Figure 2. Infections occur before the onset of symptoms of autoimmune disease, making links to specific causative agents difficult. When a person is first infected (day 0), usually no symptoms are apparent. Signs and symptoms of autoimmune disease are clearly present and easily confirmed by physicians during the chronic stage of autoimmunity. However, the infection has been cleared by this time, making it difficult to establish that an infection caused the autoimmune disease. Modified from (16).