The virus was first identified in 1947 in a rhesus monkey in the Zika Forest. Our maps show how it spread slowly at first, then last year began a rapid invasion of the Americas.
Researchers are looking into the possible link to birth defects — and suspected cases of hearing loss in adults. First they need a fast test to identify the virus.
An investigation is finding "profound abnormalities" in babies with microcephaly who are born to Brazilian mothers suspected of having the Zika infection.
On a trial basis, a British company is releasing genetically modified mosquitoes in Brazil to try to reduce the Aedes aegypti population — the species spreading Zika.
The government is trying to wipe out Zika virus, which has been linked to a severe birth defect. But is it doing enough to help families whose children have been affected?
The Centers for Disease Control is concerned about an increase in a rare birth defect in Brazil that could be linked to the virus. But Zika is not just in Brazil; see a map of where it is spreading.