In this prospective observational study the investigators will report on 20 male subjects with proven WHO-classification Zika infection. These subjects will be followed up for a maximum of 12 months to observe the presence, viral load and infectivity of Zika virus (ZIKV) in semen over time.

In this prospective observational study the investigators will report on 20 male subjects with proven WHO-classification Zika infection. These subjects will be followed up for a maximum of 12 months to observe the presence, viral load and infectivity of Zika virus (ZIKV) in semen over time.

Knowledge of the possible presence, infectivity and persistence of ZIKV in semen will provide evidence-based data for

1. estimating of the risk of sexual transmission of ZIKV in the general population
2. antenatal guidelines for the prevention of sexual transmission of ZIKV to the fetus
3. advising couples on the length of time that pregnancy should be avoided in women wishing to conceive after their partner's ZIKV infection
4. strategies to prevent transmission of ZIKV infection through assisted reproductive treatment (ART)
5. advice on gamete cryopreservation
6. optimising investigations for diagnosis of ZIKV in males.

Inclusion Criteria:

• Male aged 18-50 years
• ZIKV symptoms within the preceding thirty days
• Confirmed ZIKV infection (WHO criteria)
• Able to ejaculate to produce a semen sample

Exclusion Criteria:

• Current urological malignancy

25 men aged 18-50 years with ZIKV symptoms within the preceding thirty days & confirmed ZIKV infection (WHO criteria). The study setting is a private fertility clinic in Trinidad and Tobago - a country with a current ZIKV epidemic.