Short answers, pulled from the story.
Autoimmune disease results from a malfunction of the adaptive immune system, which mistakenly targets healthy tissue as if it were foreign. Autoinflammatory disease involves a malfunction of the innate immune system instead. Both can produce similar symptoms such as rash, swelling, and fatigue, but the underlying mechanism is different.
More than 80 autoimmune diseases are currently recognized. Recent scientific evidence suggests there may be more than 100 distinct conditions. A 2025 study used a list of 105 conditions drawn from The Rose and Mackay Textbook of Autoimmune Diseases.
Women make up approximately 80% of autoimmune disease patients. Hormonal factors are a likely contributor; some diseases flare during pregnancy when hormone levels are high and improve after menopause. Under-reporting by men, who may interact less with the health system, may also be a factor.
Current research suggests environmental influences may account for up to 70% of autoimmune disease cases. Implicated factors include chemicals such as hydrazines and trichloroethylene, ultraviolet radiation, pesticide exposure, and infection with SARS-CoV-2, which has been linked in large-scale data to increased risk of new-onset autoimmune conditions.
A 2012 study by Hayter and Cook estimated cumulative US prevalence at 5.0%, with 3.0% for males and 7.1% for females, based on 81 diseases. A 2025 study using electronic medical records from more than 15 million patients found a prevalence of 4.6% based on 105 conditions.
Most autoimmune diseases are chronic and have no definitive cure. Standard treatments include nonsteroidal anti-inflammatory drugs, glucocorticoids, disease-modifying anti-rheumatic drugs, and replacement therapies for specific deficiencies such as insulin in type 1 diabetes. Newer approaches under study include monoclonal antibodies, antigen-specific immunotherapy, regulatory T cell therapy, and stem cell transplantation.