LIBERIA (CBS Local) – Doctors have made a disturbing discovery about 2014’s deadly Ebola outbreak in Africa. A woman who survived the virus is believed to have spread it one year after her initial infection.

The study, published on July 23 in the journal Lancet Infectious Diseases, reports that a 33-year-old Liberian woman infected her husband and two sons a year after the epidemic swept across West Africa. Unfortunately, the mother’s 15-year-old died, while her husband and younger son survived their infections.

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“The Ebola virus hides in places where it can escape the antibodies from a body’s immune system, so there is a need for vigilance,” Dr. David Heymann of the London School of Hygiene and Tropical Medicine said, via CBS News.

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Doctors say the woman’s pregnancy after the infection may have caused the deadly infection to resurface. “The suspicious illness she had following delivery may have been a re-activation of Ebola, but we have no confirmatory tests,” the study’s lead author Dr. Emily Kainne Dokubo of the CDC explained.

Health officials have seen previous incidents where men have spread Ebola to women through sex. The virus can reportedly survive in semen for more than a year, but the Liberian woman’s case is the first time scientists have linked the spread of Ebola to a woman after such a long period of inactivity.

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More than 11,000 people died across Guinea, Liberia, and Sierra Leone from 2014 to 2015. It was the largest Ebola epidemic on record.