Health officials say the Ebola outbreak, centered in West Africa, is the deadliest ever.
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A second American aid worker in Liberia has tested positive for Ebola, according to the Christian humanitarian group she works for.

Nancy Writebol is employed by Serving in Mission, or SIM, in Liberia and was helping the joint SIM/Samaritan’s Purse team that is treating Ebola patients in Monrovia, according to a Samaritan’s Purse statement.

On Saturday, Samaritan’s Purse announced that American doctor Kent Brantly had become infected. The 33-year-old former Indianapolis resident had been treating Ebola patients in Monrovia and started feeling ill, spokeswoman Melissa Strickland said. Once he started noticing the symptoms last week, Brantly isolated himself.