President Barack Obama has asked Congress for more than $US1.8 billion ($A2.5 billion) in emergency funding to help fight the Zika virus.
In an announcement on Monday, the White House said the money would be used to expand mosquito control programs, speed development of a vaccine, develop diagnostic tests and improve support for low-income pregnant women.
While most people who catch the mainly mosquito-spread virus experience few symptoms, there are concerns the fetus of infected pregnant women may be at risk for a rare birth defect that causes brain damage and an abnormally small head.
"What we now know is that there appears to be some significant risk for pregnant women and women who are thinking about having a baby," Obama said in a CBS interview aired on Monday.
He added that "there shouldn't be a panic on this".
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The Pan American Health Organization reported 26 countries and territories in the Americas with local Zika transmission, the White House said.
To date, there has not been transmission of the Zika virus by mosquitoes within the US, but some Americans have returned to the US with Zika infections from affected countries in South America, Central America, the Caribbean and the Pacific Islands.
The Centers for Disease Control and Prevention reports 50 laboratory-confirmed cases among US travellers from December 2015-February 5, 2016, the White House said.
