From Travel Weekly:
Carnival Cruise Lines said it has been advised that a passenger on one of its ships is a lab supervisor at Texas Health Presbyterian Hospital, where a man died from Ebola virus earlier this month.
In a statement, Carnival said the passenger shows no symptoms of illness. It has been 19 days since she was in a lab with testing samples, Carnival said. “She is deemed by CDC (Centers for Disease Control and Prevention) to be very low risk,” the Carnival statement said.

Read More: http://www.travelweekly.com/Cruise-Travel/Carnival-passenger-who-handled-Ebola-samples-deemed-low-risk/

A few important things to keep in mind:

1. The passenger shows no symptoms and other passengers are not at risk

2. The passenger is being isolated out of an "abundance of caution"

3. The only impact to passengers on the Carnival Magic sailing has been the inability to port in Belize City, Belize [UPDATE: Passengers other than the nurse and her traveling companion were able to debark in Belize City as scheduled]

4. Carnival and other cruise lines are asking health questions to screen for Ebola during cruise embarkation and following up with medical screening when necessary

There's no reason to panic or be concerned about catching Ebola on a cruise ship, and passengers with an upcoming cruise should be aware that "Fear of Ebola" is not a covered reason for cancellation under most insurance policies.

For the facts about Ebola, visit the US Centers for Disease Control website at http://www.cdc.gov