Reactive Arthritis

■ In reactive arthritis (ReA), exposure of the host to infectious agents leads to the development of an inflammatory arthritis and other manifestations of systemic disease in the absence of an ongoing infectious process. ■ Approximately 50% of ReA and undifferentiated oligoarthritis cases can be attributed to a specific pathogen by a combination of culture and serology. The predominant organisms are Chlamydia, Salmonella, Shigella, Yersinia, and Campylobacter species. ■ The annual incidence of ReA, found to be 28/100,000 individuals in one study, may exceed that of rheumatoid arthritis. ■ In a study of 91 individuals exposed to food-borne Salmonella enteritidis, 17 (19%) individuals developed ReA. Other studies have estimated the frequency of ReA following exposure to potential etiologic agents to be on the order of 10%. ■ Reactive arthritis characteristically involves the joints of the lower extremities in an asymmetric, oligoarticular pattern. ■ A dactylitis ("sausage digit") pattern in the feet is typical of ReA. ■ Enthesopathy (inflammation at the sites of insertion of tendons and ligaments into bone) and anterior uveitis are often found in ReA, as in other seronegative spondyloarthropathies. ■ Cutaneous manifestations of ReA include: keratoderma blenorrhagicum, a papulosquamous rash affecting the palms and soles; nail dystrophy; circinate balanitis, characterized by shallow ulcers on the glans or the shaft of the penis; and oral ulcers, typically painless.