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A mosquito-borne virus that has rapidly spread across 21 countries and territories of the Americas since May 2015 will likely continue to stretch across more countries, the World Health Organization said.
The first cases of the latest Zika virus outbreak were reported in Brazil in May 2015, according to WHO.
The virus typically causes fever, rash, joint pain and red eyes, and has been tenuously linked with a congenital condition in newborns. The illness is typically mild and can present symptoms for as long as one week, according to the Centers for Disease Control and Prevention.
The virus' "rapid spread" is exacerbated by two conditions, according to WHO: a lack of immunity because the Americas had not been previously exposed to the virus and the prevalence of the Aedes mosquitoes -- the main carrier of Zika -- in all of the region, save Canada and continental Chile.
The Pan American Health Organization, which serves as WHO's Regional Office for the Americas, said it anticipated the Zika virus would "continue to spread and will likely reach all countries and territories of the region where Aedes mosquitoes are found."
Transmission of the virus by Aedes mosquitoes is well documented, health officials said, although researchers continued to investigate other possible transmission routes.
Earlier this month, doctors in Hawaii noted a child born with a health defect which caused its head to be unusually small apparently contracted Zika virus before birth through his mother. She had been diagnosed with Zika in Brazil, according to the Hawaii State Department of Health.
Scientists have also found evidence Zika may be transmitted through sexual contact, but more information is needed to confirm the link, WHO said.
The virus is also occasionally transmitted through blood. Precautions have already been put in place to ensure safe blood donations and transfusions, according to WHO.
The Pan American Health Organization released the following recommendations for stymieing the spread of Zika virus: