NEW YORK (AP) — U.S. health officials are warning Americans not to travel to the three African countries hit by an outbreak of Ebola.

The travel advisory issued Thursday applies to non-essential travel to Guinea, Liberia and Sierra Leone. The outbreak in West Africa has killed more than 700 people since March.

READ MORE: Stray Bullet Kills Man Eating Thanksgiving Dinner Inside Norristown Home, Police Say

Officials at the Centers for Disease Control and Prevention say the risk of the deadly disease coming to the United States remains small.

READ MORE: Pennsylvania Senate Scramble Could Include Dr. Oz And Former Bush Official: 'This Crowd Is So Big And Unknown'

The agency sent about two dozen staffers to West Africa to help try to control the outbreak there. Officials announced Thursday they will send 50 more in the next month.

The last time the CDC issued such a warning during a disease outbreak was in 2003 because of SARS in Asia.

MORE NEWS: Shoppers, Retailers Alike At Cherry Hill Mall Cherish 'More Traditional' Black Friday

(© Copyright 2014 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)