The Center for Disease Control has positively diagnosed five people in the United States with the Wuhan coronavirus. The death toll count is 50, and numbers are expected to rise exponentially since the virus has spread globally.

One similarity in the all five confirmed cases in the U.S. is they all have traveled back to the U.S. from Wuhan, where the virus is believed to have originated. Three cases were confirmed on Sunday.

The latest case of the coronavirus was confirmed in Maricopa County, Arizona. The individual is in good condition, and has since then been transported to a local hospital and is currently in isolation.

The U.S. cases of the virus are in Everett, Washington, Chicago, Illinois, Maricopa County, Arizona, and Orange County, California and Los Angeles County, California. The patients are in isolation at hospitals.

Dr. Nancy Messonnier, director of CDC’s National Center for Immunization and Respiratory Diseases, said she’s been flooded with calls “all day and night” from doctors across the country about potential cases.

Symptoms, if any, are fever, cough and/or difficulty breathing, recent travel to Wuhan, China, and/or close contact with a confirmed or suspected case of coronavirus.

China officials warn the virus could spread much faster than initially expected. There are no vaccines for the coronavirus, and officials are concerned people can spread the virus to others before they are aware they have it because they may not have any symptoms.

Scientist at Imperial College London estimated each person infected with the virus has gone on to infect two to three additional people.

“This implies that control measures need to block well over 60% of transmission to be effective in controlling the outbreak,” they said in a statement. “This makes it more difficult to put in place effective control measures. A lot of people are working furiously to try and control this epidemic.”