Underdiagnosis of chikungunya virus infections in symptomatic Dutch travelers returning from the Indian ocean area

A putative underdiagnosis of clinical chikungunya virus infection in Dutch travelers to the Indian Ocean area was addressed by retrospective screening of all sera for which requested dengue virus serology was negative in the period 2007 to 2010. Evidence for a recent infection was observed in 6.5% of 107 patients, indicating a substantial underdiagnosis and the need for increased awareness among physicians.