The positivity in-time of CHIKV RNA in urine will be evaluated in comparison with viremia. Patients with suspected acute CHIKV infection will be asked (by written informed consent; annex 1) to provide urine samples within 72 hours after onset of disease, followed by urine samples on day 7, day 10, day 14 and three urine samples 3, 4 and 12 weeks after onset. They will be asked to provide serum samples within 72 hours after onset of disease, followed by serum samples on day 7, day 10, day 14. In total, twenty patients with an initial positive result of CHIKV RT-PCR on serum will be included for follow-up. The number of urine samples that will be tested is 140.