President Barack Obama has appointed former White House adviser Ron Klain as the United States Czar to Ebola as the death toll rises past 4,500, according to The Associated Press.

Klain is a lawyer who previously served as chief of staff to Vice Presidents Joe Biden and Al Gore and he will no oversee the U.S. response to the virus, CNN reported.

Klain's appointment coincided with a new Ebola incident on a cruise ship headed to Mexico, according to the AP.

Authorities said a Texas health worker, who was not ill but may have had contact with specimens from an Ebola patient, was quarantined on a cruise ship that departed last Sunday from the port of Galveston, Texas, the AP reported.

The cruise, named Carnival Magic, is operated by Carnival Cruise Lines, and had to skip a planned stop in Cozumel, Mexico, because of delays getting permission to dock from Mexican authorities, the cruise line said, due to the Ebola incident, according to the AP.

A Mexican port authority official said the ship was denied clearance to avoid any possible risk from Ebola, CNN reported. The ship was scheduled to return to Galveston on Sunday.

The cruise company said that the woman, a lab supervisor traveling with her spouse, remained in isolation "and is not deemed to be a risk to any guests or crew," according to the AP.

According to the Centers for Disease Control and Prevention, Ebola isn't contagious until symptoms appear because it isn't spread through the air like the flu. People can only catch it by direct contact with a sick person's bodily fluids, such as blood or vomit, the AP reported.

So far, the worst-hit countries have been Guinea, Liberia and Sierra Leone, where Ebola has killed 4,546 since the outbreak of the hemorrhagic fever began there in March, according to a report on Friday from the World Health Organization, according to the AP.