No one has reported getting the disease on U.S. soil this year, but some fear there has been inadequate research and preparation for mosquito season.
Most of those infected with Zika don't have visible symptoms, and testing for the disease can be unreliable and difficult.
Budget constraints have been a concern as well. Congress gave $1.1 billion in funding toward Zika research and treatment. Now, they haven't made many claims about additional funding.
Some states don't have the resources to combat an outbreak, and other states barely practice surveillance of mosquito-borne illnesses.
Read more about concerns surrounding Zika this year at www.usatoday.com.