Health screening at the Conakry Maritime Port in Guinea.

A disease threat anywhere is a disease threat everywhere, and the Ebola epidemic has shown how easily infectious diseases can cross borders—land, rivers, and even oceans. From the start of the epidemic, porous country borders among the three West African countries and a highly mobile population aided the rapid spread of Ebola from its origin in Guinea. In West Africa, border control measures are mostly nonexistent—getting to another country is often as simple as taking a boat across a river. This makes it easy for a disease like Ebola to spread across countries and it complicates contact tracing.

In West Africa, CDC works with airlines, airports, ministries of health, and other partners to provide technical assistance for conducting exit screening and travel restriction in countries with Ebola. Exit screening helps to identify travelers who may have symptoms of Ebola, or who have been exposed to Ebola, to prevent them from leaving a country until it is confirmed they are not sick.

Once travelers land in the United States, more measures are in place to protect the public. CDC works closely with partners at major U.S. ports of entry to recognize signs of infectious disease in travelers. Since October 2014, CDC has been working with CBP to identify travelers who could have been exposed while in West Africa and conduct enhanced entry screening at five U.S. airports. CDC has similarly been working with the states, providing information and guidance, so that they can monitor these travelers once they arrive at their destinations. Screening and monitoring not only protects the health of these travelers, but also reduces the chances of them spreading Ebola to others.