The Zika virus is transmitted by the Aedes aegypti mosquito, which is also known to carry the dengue, yellow fever and Chikungunya viruses.
First detected in Africa in 1947, the virus baffled health experts in the second half of 2015 by spreading quickly through Central and South America.
Symptoms include fevers, mild headaches, skin rashes, joint pain and conjunctivitis.
While lacking complete clinical evidence, doctors and researchers increasinglysuspect Zika is connected to cases of microcephaly -- a neurological disorder in which infants are born with smaller craniums and brains.
The problem has been especially severe in Brazil, where suspected cases increased to 3,893 by Jan 16 from 3,530 cases 10 days earlier. Fifty infant deaths have been linkedto the condition.