Zika virus 'scarier than initially thought'

The mosquito-borne disease is a cause of microcephaly, according to the World Health Organization, but Schuchat said experts are now linking the virus to premature birth, eye problems and other neurological conditions in babies born to mothers who were infected while pregnant.

These concerns are no longer limited to exposure to the virus only during the first trimester. There is reason to be concerned throughout the pregnancy.

Schuchat also noted revised surveillance maps of the Zika-carrying mosquito, Aedes aegypti, released last month, showing that the insects could be more widespread than previously thought, reaching as far north as San Francisco and New York.

Fauci said researchers are on track with their goal to begin a clinical trial for a vaccine in September. He also said his teams have screened 62 existing drugs as possible treatments. Fifteen have been identified for further research, although he cautioned they may not pan out.

Progress is also being made in the lab with the recent molecular discovery that potentially sheds light on why the virus, which is so similar to dengue fever, infects neurological tissue.

Fauci said there are now two mouse models that could help researchers understand how and why neurological tissue is infected by the virus. And with a monkey model is allowing, they can compare how the virus behaves when the host is pregnant as compared with not pregnant.

The end point is to protect Americans, especially pregnant women, which is why the agencies have been working around the clock. They can't say for sure how widespread the virus will be in the United States.

So far there have been at least 346 cases of the virus in the continental United States, according to the CDC. Most of these among travelers returning from currently affected countries and territories. There are no reported cases of mosquito transmitted Zika infection at this time.

"While we absolutely hope we don't see widespread local transmission in the continental U.S., we need the states to be ready for that," Schuchat said.

In the U.S. territories of Puerto Rico, American Samoa and the U.S. Virgin Islands, however, there have been 354 cases of the virus so far, most of them locally transmitted in their tropical climates. This is why the CDC is concerned. Schuchat said there could be hundreds of thousands of cases of Zika virus in Puerto Rico and that hundreds of babies could be affected by microcephaly.

As they've done before, they appealed to Congress for an emergency $1.9 billion to keep the virus at bay.

In February, the administration asked Congress for $1.9 billion in emergency supplemental funding to fight the Zika virus. Congress has yet to act on that request.

Last week, the White House said it was redirecting $589 million to the cause. The White House made it clear the $1.9 billion was still needed and the redirected money, which includes $510 million of unused Ebola funds, would need to be replaced.

Fauci echoed that Monday. He said the money also being taken from work being done on tuberculosis and malaria.

"If we don't refurbish that money, those programs are going to stop when they reach the point that they run out of money. What we're trying to do is keep everything going," he said.

Then he became more direct, "I can't image that we're not going to be given the money when we reach the point when every time we come in front of you we tell you things that are more serious."

Without directly telling Congress to approve the funding request, White House press secretary Josh Earnest told reporters the information from Schuchat and Fauci would "serve as motivation for members of Congress to pay careful attention to this top priority."

"We can't assume that we're not going to have a big problem. We know with other viruses we've had bigger problems than we expected. We're taking this very seriously." Schuchat said.