Study design, population, materials and methods: Prospective cohort study of persistence of zika virus (ZIKV) in semen samples of adult male patients who attend the outpatient clinic of the Institute of Tropical Medicine in Antwerp and who have a confirmed ZIKV infection (positive RT-PCR for ZIKV in a serum or urine sample at the time of inclusion). Clinical and epidemiological data will be recorded in a standardized Case Record Form (CRF). Baseline serum, blood and urine samples will be collected as required for routine clinical evaluation of an individual case and for arbovirus antibody detection assays; sampling of serum and urine collection for RT-PCR will be scheduled weekly until 2 consecutive semen samples test negative in ZIKV RT-PCR. ZIKV isolation will be attempted from each available semen sample with a positive PCR result. The semen analyses will include: sperm count, morphology, motility, leukocyte and erythrocyte count and pH of the semen. Serum at 4 weeks will be collected for ZIKV antibody detection assay.