Two people in the U.S have been diagnosed with a potentially deadly virus called MERS, which up until now, was mostly seen in the middle east. Both had worked recently as health workers in Saudi Arabia.
MERS, Middle East Respiratory Syndrome, has come to the United States.
The virus was first confirmed in Saudi Arabia in 2012 and has killed about a third of the hundreds it has infected.
MERS does not appear to spread easily between humans like the flu, for example.
The risk to the general public remains low, according to the Centers For Disease Control And Prevention.
It takes close contact with a sick person, usually a healthcare worker or a loved one, to catch the virus.
MERS is in the same family of viruses as the common cold.
MERS attacks the respiratory system.
Symptoms include fever and cough and can progress to pneumonia and kidney failure.
Experts don't know exactly where the virus came from, but it has been linked to infected camels in Saudia Arabia and other countries in the Middle East.
There is no vaccine or medicine to prevent or cure MERS.
To help protect yourself the CDC advises people to wash their hands, not touch their eyes, nose or mouth with unclean hands, and to avoid close contact with sick people.