Making its way from Latin America to the U.S. shores, the Zika virus is spreading. And as the mosquito population grows — and the summer rapidly approaches — concern is rising over a potential U.S. outbreak.
On Friday, a 70-year-old man in Puerto Rico infected with the disease died from complications, according to health officials, becoming the first U.S. casualty from the deadly infection. In an interview with CNBC, a top public health official warned the United States could very well see more instances.
"The mosquitoes that carry Zika are in parts of the United States," Dr. Denise Jamieson, chief of the women's health and fertility branch of the Centers for Disease Control and Prevention, told "On the Money" in a recent interview.
"In the continental U.S., there are no cases of local transmission from mosquito bites," Jamieson said, but added that in Puerto Rico "there are ongoing cases of Zika virus." The island has become ground zero for the virus, where hundreds have been diagnosed.
There's currently no vaccine for Zika, but Jamieson told CNBC that "researchers are working" on one. "There are some vaccines to other related viruses so researchers have a jump-start on that. But it's still going to take time."
"In the meantime, it's really important that pregnant women know how to protect themselves" from Zika. "Notably, avoid mosquito bites."
Zika is primarily transmitted via mosquito, but can also be spread through sexual contact and blood transfusions. Yet what makes Zika more mysterious is that for most of those infected with the mosquito-borne virus, the symptoms are minor.
"Zika is generally a very mild disease," Jamieson told CNBC, and "in adults it causes fever, rash, red eyes, maybe some joint pain." As events have shown, however, the same virus can have far more devastating outcomes in pregnant women, causing birth defects like microcephaly and other anomalies.
Microcephaly is a birth defect where a baby's head is significantly smaller than normal, and according to recent reports, brain damage in many of those infected babies may be far more significant than originally believed.
In Brazil, the first appearance of the outbreak, the virus has resulted in rare birth defects in more than 2,500 newborns, according to the World Health Organization. The disease has spread through South America, Central America to the Caribbean and Mexico, and is heading toward the United States.
CDC Director Tom Frieden told Time in a recent interview that he wouldn't be surprised if there were local clusters of outbreak in the Southern U.S. this summer, and Jamieson agreed.
"We know from other related diseases that are carried by same mosquitoes, that we are likely to see a small number of cases in the continental United States," she said.
"On the Money" airs on CNBC Saturday at 5:30 am EDT, or check listings for air times in local markets.