This is very sad, on many levels.

Five doctors, nurses, and hospital staffers who are co-credited as authors of a paper about Ebola published today in Science have already died of the disease, the publication says. All five worked at Kenema Government Hospital in Sierra Leone, and all were “experienced members of the hospital’s Lassa fever team.” (Lassa fever is “a hemorrhagic illness with many symptoms similar to Ebola.”)

One of the victims was Sheik Umar Khan, the doctor supervising Sierra Leone’s Ebola response, whose death last month was widely reported.

Three of the victims were infected while caring for another colleague of theirs who contracted the virus while pregnant, Science says. One of those victims, Mbalu Fonnie, was the nursing supervisor of the hospital’s Lassa fever ward and had survived a Lassa fever infection.