Due to an outbreak of Ebola Virus Disease (EVD) in the west African nations of Liberia, Guinea, and Sierra Leone, the Centers for Disease Control has issued Health Travel Warnings for those three countries advising against nonessential travel and has provided guidance to reduce the potential for spread of EVD. A CDC Level 2 Travel Alert has been issued for Nigeria recommending that travelers practice enhanced precautions. The Department of State has issued Travel Warnings for Liberia, Sierra Leone and Nigeria.
Additionally, these countries have travel warnings for other reasons:
For more from Centers for Disease Control (CDC): http://www.cdc.gov/vhf/ebola/index.html