CAMBRIDGE, Mass. (AP) — Harvard University is advising students and staff members to avoid non-essential travel to three West African countries with Ebola outbreaks.

A Harvard spokesman says an email was distributed Friday addressing travel to Sierra Leone, Guinea and Liberia.

The letter from Provost Alan Garber and Health Services Director Paul Barreira also asks anyone who has traveled to those countries or to Nigeria in the past four weeks to contact the health services office for a telephone assessment before returning to the Cambridge, Massachusetts, university’s campus. It says the actions are guided by the U.S. Centers for Disease Control and Prevention and are meant to protect Harvard students and staff members at home and abroad.

The World Health Organization says the Ebola outbreak has killed nearly 1,000 people.

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