Reactive arthritis (ReA) is an autoimmune conition that develops in response to an infection in another part of the body. Coming into contact with bacteria and developing an infection can trigger reactive arthritis. It has symptoms similar to various other conditions collectively known as "arthritis," such as rheumatism. It is caused by another infection and is thus "reactive", i.e., dependent on the other condition. The "trigger" infection has often been cured or is in remission in chronic cases, thus making determination of the initial cause difficult.