Doctors say a 44-year-old patient with MERS exposed two health care workers at this Orlando hospital.
Both had flu-like symptoms and one has been hospitalized.
Another 20 health care workers who may have been exposed to the Middle East Respiratory Syndrome were sent home as a pre-caution.
"It has a very high mortality rate. About a third of the people who have acquired this infection died of it," said William Schaffner.
The virus causes coughing, fever and sometimes pneumonia which can be deadly. More than 500 people in the Middle East have been infected this year, the majority of cases are in Saudi Arabia.
The infected person came to the U.S. from Saudi Arabia on May 1st.
The passenger took four flights from Jeddah to London, then to Boston, Atlanta and finally Orlando.
While flying, the traveler developed flu like symptoms and was admitted into the hospital in Florida a week later.
The CDC has started posting these warnings at major airports explaining the risk to travelers.
The CDC is taking the situation very seriously and working in close coordination with local authorities," said White House Press Secretary, Jay Carney.
The world health organization is keeping an eye on MERS and says despite a recent spike in cases, it's not yet a global health emergency.
Last week a patient in Indiana was hospitalized with MERS, but has since been released.
Currently, there is no cure or vaccine for the virus.
Symptoms include fever, cough and shortness of breath.
It can lead to pneumonia and kidney failure.