Background . Chikungunya is a reemerging disease. In 2005–2006, a severe outbreak occurred on Reunion Island in the southwestern part of the Indian Ocean. Other islands in this area were affected during the same period.

Methods . Adult patients with acute chikungunya (defined as onset of fever and/or polyarthralgia in the 5 days preceding consultation) and laboratory-confirmed chikungunya who were referred to Groupe Hospitalier Sud Reunion during the period from March 2005 through April 2006 were included in this retrospective study. Their clinical and laboratory features are reported.

Results . Laboratory-confirmed acute chikungunya was documented in 157 patients. The mean age of patients was 57.9 years, and the ratio of male to female patients was 1.24 : 1. Sixty percent of patients had at least 1 comorbidity. Ninety-seven patients (61.8%) were hospitalized, and 60 (38.2%) were treated as outpatients. Five fatalities were reported. One hundred fifty-one patients (96.1%) experienced polyarthralgia, and 129 (89%) experienced fever. Gastrointestinal symptoms were reported by 74 patients (47.1%), and skin rash was reported by 63 (40.1%). Hemorrhagic signs were rare. Lymphopenia and hypocalcemia were the prominent laboratory findings. Severe thrombocytopenia was rarely observed.

Conclusions . Chikungunya virus can be responsible for explosive outbreaks of disease. Polyarthralgia and fever are the 2 main clinical features. In this era of travel and globalization, chikungunya should be considered in the differential diagnosis of febrile polyarthralgia with an abrupt onset.