Arthropod-borne viruses (arboviruses) comprise many of the most important emerging pathogens due to their geographic expansion and their increasing impact on vulnerable populations. In 2015, Zika virus (ZIKV) became the newest emerging public health threat to Latin America, with more than 14,000 cases in Salvador, Brazil, and accruing substantial evidence of resultant Guillain-Barré and microcephaly. After severe outbreaks of chikungunya virus (CHIKV) wherein some islands experienced more than 90% of residents infected, the Caribbean islands are now witnessing large- scale ZIKV exposure and infection. We propose to determine the true incidence of ZIKV compared to CHIKV and dengue virus (DENV) disease in Grenada, and identify the demographic and ecological drivers for ZIKV transmission and disease. Serum collected from participants will be tested by ELISA and PCR to document acute ZIKV infection and characterize the spectrum of disease, severity and impact of ZIKV in Grenada. Participants, especially pregnant women, will be followed to determine long-term consequences of ZIKV disease, including any microcephaly resulting from antenatal ZIKV infection. Clinical manifestations of disease in those with and without prior DENV infection will be compared to determine if previous DENV exposure alters resultant Zika disease. This information will provide crucial data to determine the full spectrum and medical sequelae from ZIKV in a naïve population.