CHICAGO (WLS) --Health experts say they expect substantially more people to become infected with the the Zika virus.
Travelers - and even some Olympic hopefuls in the Chicago area - are faced with the decision of whether or not to travel to countries where mosquitoes carry the virus.
Experts say it may only be a matter of time before some species of mosquitoes in this country develop the ability to transmit the virus. About 40 million people a year travel to and from the U.S. and countries affected by the Zika virus, and doctors say its likely hundreds of thousands of them will be infected with the virus.
The Sunset Travel Agency is filled with brochures for sunny vacation spots on beaches in Mexico and South America, and Ryan Roman is booking plenty of trips to those places. But he's also getting a lot of questions, especially from women of childbearing age. One client - a pregnant woman headed to Puerto Vallarta for a wedding - decided to stay home.
"She went to see her doctor and she was in her third trimester, so her doctor advised her not to go to Mexico," Roman said.
The virus can be especially dangerous for pregnant women and women hoping to become pregnant because it is suspected of causing birth defects in newborns. It is usually spread by mosquito bites.
"Unfortunately we're likely to continue to see substantial spread around the world with a pace that sees lots of Zika," said Tom Frieden, Centers for Disease Control.
The Zika virus is believed to have originated in South America. In El Salvador, they are using the military to fumigate the streets of neighborhoods controlled by gangs.
Romeoville resident Samantha Mejia just returned from Honduras and discovered she had mild symptoms of the virus.
"I had flu-like symptoms, didn't really think anything of it, felt much better the next day - but the next day actually, broke out in a rash," Meija said.
While it is still months away, some travel agents say the threat of the virus is a concern to some athletes and fans travelling to Brazil this summer for the Olympics. Tera Moody of Chicago is running in the U.S. Marathon Olympic trials Saturday, hoping to qualify for a trip to Brazil. Zika is a concern, but she says it won't stop her.
"I really feel strongly about not living in a bubble and it's a risk I would be willing to take," Moody said.
The online travel website Orbitz issued a statement saying they are advising travelers to visit the Centers for Disease Control and Prevention website for the latest information regarding travel to areas affected by the Zika virus. Experts from the center say they are still in the early stages of studying and learning about the virus.