With summer fast approaching, a National Institute of Allergy and Infectious Diseases expert is warning that mosquitoes carrying the Zika virus could soon be descending across the country.

Allergy and Infectious Diseases director Anthony Fauci recently sounded the alarm bell, a sobering shift from all previous public warnings about the disease, which have connected all domestic outbreaks with travel.

Fauci added local transmission could start to take place as early as a "month or so."

All Domestic Cases This far Associated With Travel

To date, there have been 544 cases of travel-associated Zika outbreaks, with none of them being described as locally acquired. Outbreaks have much more commonly taken place in such areas as Africa, the Pacific Islands, and Southeast Asia.

Over the last year, outbreaks have also occurred in Brazil, Puerto Rico, the U.S. Virgin Islands and American Samoa.

The Zika virus is known to be typically transmitted through mosquito bites, with pregnant women found to be among those most vulnerable, leaving their unborn children at serious risk for a birth defect known as microcephaly. Symptoms include fever, rash and joint pains.

Legislation Aims to Help Fund Research

Earlier this month, the U.S. House of Representatives passed a $622.1 million bill to control the spread of the virus. The legislation calls for the cost of the funding to be fully offset by other spending cuts. The Obama administration had requested $1.9 billion in emergency funding.

The Senate previously approved a $1.1 billion funding bill, and the two sides are now expected to work to hatch out their differences.

All across the country, local governments have already started to shift resources in hopes of being able to fund the kind of research needed to get a better handle over the disease. To date, more than 40 states have already had cases of travel-associated outbreaks.

Meanwhile, Fauci has previously warned the agency will soon need a cash infusion to keep the creation of a vaccine on schedule.

"If we don't get something soon, then we're going to have a real problem," he said.

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