Chikungunya fever in Singapore: acute clinical and laboratory features, and factors associated with persistent arthralgia.

BACKGROUND: In Singapore, the first local outbreak of chikungunya was reported in January 2008, followed by a larger outbreak occurred in August 2008. During the initial outbreak period, a strict containment strategy was adopted and all chikungunya PCR-confirmed cases were isolated and hospitalised at the designated national outbreak management centre.
OBJECTIVES: To detail daily clinical and laboratory features of chikungunya cases during acute illness, and determine factors associated with persistent arthralgia at week 6. STUDY
DESIGN: Prospective cohort study of patients with PCR-confirmed chikungunya infection and hospitalised within 5 days of illness onset, from 1st August to 10th November 2008. Post-hospital discharge, patients were followed up at the specialist outpatient clinic, and assessed for arthralgia at week 6 of illness.
RESULTS: Of the 97 patients in the study, the most common presenting symptoms were fever (89.7%) and arthralgia (87.6%). Mean nadir leukocyte and platelet counts were 3.5(SD 1.9) × 10(9)/L and 165(SD 42) × 10(9)/L respectively. Of the 39 patients who were evaluated at week 6, 14 (35.9%) had persistent arthralgia. Those with persistent arthralgia tended to be females (p = 0.003), and had a lower peak creatinine level (p = 0.036) than those without. Peak viral load (p = 0.664), and duration of fever (p = 0.056) and viremia (p = 0.55) respectively, were not significantly different between those with persistent arthralgia and those without.
CONCLUSIONS: This study details the daily clinical and laboratory features of chikungunya patients during acute illness. Those with persistent arthralgia tended to be females, who had significantly lower peak creatinine level.