Here’s what the taxi driver said:
“Jiminez Grugbaye says he drove the taxi that ferried Duncan and a sick pregnant woman in search of a hospital. All five people who rode in the cab have either died of Ebola or are infected with it
...
‘She was helpless. She, she was not able to walk by herself,’ he told NBC.
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Mr Grubaye said he noticed a stream of blood trickling from Williams’ mouth. However, her family told him that she had only bit her tongue and that she was suffering a miscarriage - not sick with Ebola.
I think it is possible that Duncan wasn’t told the truth and came to America without knowing what happened to his landlord’s family. It doesn’t say whether the taxi driver got sick or not.