Reverend Dr. Herman Browne voluntarily quarantined himself for 21 days after his wife's friend tested positive for Ebola. On Sunday, he returned to his church, Trinity Cathedral, to preach to his congregation about Ebola prevention. Jon Hamilton/NPR hide caption

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Thomas Eric Duncan, the first Ebola patient diagnosed in the U.S., at a wedding in Ghana. Texas Health Presbyterian Hospital Dallas, where Duncan was being treated for the disease, on Wednesday, Oct. 8, 2014 said Duncan has died. Wilmot Chayee/AP hide caption

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Senegalese fencer Abdoulaye Thiam (left) competed against Jason Rogers of the U.S. during the 2008 Olympics. Due to Ebola fears, a World Cup fencing event set for Senegal this month has been canceled. Philippe Desmazes/AFP/Getty Images hide caption

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Ebola Virus, Transmission Electron Micrograph Of The Ebola Virus, Rna Virus, Cause Of Hemorrhagic Fever. BSIP/UIG via Getty Images hide caption

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Members of the California Nurses Association rallied in Sacramento, Calif., in May, in anticipation of contract negotiations with Kaiser Permanente that began in this fall. April Dembosky / KQED hide caption

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An ambulance carrying Amber Vinson, the second health care worker to be diagnosed with Ebola in Texas, arrives at Emory University Hospital in Atlanta on Wednesday. David Tulis/AP hide caption

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At a CDC training session for clinicians headed to West Africa, a medical worker practices sanitizing hands after drawing blood from a mannequin portraying an Ebola patient. Brynn Anderson/AP hide caption

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During a news conference on Sunday, Texas Health Presbyterian Hospital Chief Clinical Officer Dr. Daniel Varga answers questions about a health care worker who now has Ebola after providing care for Thomas Eric Duncan. Varga is expected to testify before a House panel looking into Ebola response. Brandon Wade/AP hide caption

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