[Update on reactive arthritis].

The following review summarizes the evidence on reactive arthritis (ReA), focussing on the latest relevant work on epidemiology, diagnosis, pathogenesis, and treatment. ReA is a joint inflammation that develops after a primary, extra-articular infection; the infection often involves the urogenital or gastrointestinal system, and less frequently the respiratory tract. The microbial agent causing the primary infection and triggering the arthritis cannot be cultured from the synovial compartment by standard methods; however, bacterial antigens or nucleic acids originating from Chlamydia trachomatis and other microbes can be detected within joint material. ReA occurs worldwide with a prevalence of 40/100,000 and an incidence of 5/100,000. The arthritis develops within days or weeks after the primary infection and usually affects the lower extremities. A dactylitis of the toes is highly typical, while axial or extra-articular manifestations are less common. The disease subsides in many cases within weeks or months, however relapses can occur and chronic forms are described in 30 % of patients.Antibiotic treatment is recommended for the active primary infection. Treatment of ReA focuses on alleviation of signs and symptoms. Severe and chronic forms require the use of immunomodulatory agents.