http://www.slate.com/articles/health_and_science/medical_examiner/2015/09/ebola_survivors_symptoms_sierra_leone_who_conference_and_how_to_help.html

FREETOWN, Sierra Leone—Ebola continues to blindside us. We still know next to nothing about the virus. It resurfaced unexpectedly in Liberia in July, two months after the World Health Organization declared the outbreak there over. One leading hypothesis suggests Ebola re-emerged because the virus lurked in semen from a man who had survived the disease, then had unprotected sex.