Federal health agencies are not trying to sneak extra money out of Congress as part of their Zika funding request, a top health official said Tuesday, as some lawmakers remain wary of where it's all going.

The money's really needed to help fight a frightening and mystifying virus one that affects the most vulnerable of all, said Dr. Tony Fauci, head of the National Institute for Allergy and Infectious Diseases.

"When the risk is to your developing baby, that trumps everything," Fauci told a seminar at the Woodrow Wilson International Center for Scholars in Washington, D.C.

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