A surgeon who contracted Ebola while working in Sierra Leone was in extremely critical condition Sunday at a Nebraska hospital, his doctors said. Dr. Martin Salia, who was diagnosed with Ebola on Monday, arrived in Omaha on Saturday to be treated at the Nebraska Medical Center’s biocontainment unit that has successfully treated two other Ebola patients this fall. Salia is “extremely ill,” said Dr. Phil Smith, who is helping oversee Salia’s treatment. The 44-year-old Salia might be more ill than the first Ebola patients successfully treated in the United States, according to the hospital. …