Shigella induced reactive arthritis.

S higella infection is the least common of the gastroenteritis-inducing organisms which are associated with reactive arthritis (ReA) in developed countries, reflecting the scarcity of the organism in these environments. A recent thorough survey of Shigella infected subjects in Finland describes an annual incidence of Shigella induced ReA of only 1.3 per million. This compares with the incidence figures of 46 per million for ReA due to Chlamydia infection, and 50 per million for other enteric pathogens, noted in a survey of the Oslo population. However, the relevant denominator for Shigella induced ReA is not the population of Finland, but the population visiting distant travel destinations—for example Egypt, India, Thailand, Congo, and Turkey—all countries where the infection was acquired by the Finnish patients. Although these countries, particularly, Turkey, are increasingly common holiday destinations for sunstarved Northern Europeans, well under 5% of the population visit such countries in any 1 year, so the incidence of ReA is more like 30–40 per million in the exposed population.