It is a medical mystery.
How did a father and two of his children become infected with Ebola virus in mid-November — more than two months after Liberia had been declared Ebola-free?
That's what Dr. Mosoka Fallah, a Harvard-trained epidemiologist in Liberia who specializes in tracing the origins of Ebola cases, is trying to determine.
The first member of the family to be diagnosed was the 15-year-old son, who was bleeding from his nose and mouth and was brought to John F. Kennedy Hospital in Monrovia, the capital city, on Nov. 17. The father told nurses that his son was 10 years old and had been injured in a fall.
Fallah notes: "The father may have lied on two counts." Fallah thinks the father lied about his son's age so that the boy would be treated in the pediatric ward. And the dad seemed to have lied about his son's condition as well; the teen was running a high fever, which couldn't be explained by the story of the traumatic fall. On Nov. 19, the lab results came back: The teen had tested positive for the Ebola virus.
Then, the father and another son, who was actually 10 years old, were both diagnosed with Ebola. The 15-year-old died of the disease.
The mother, meanwhile, had her own complicated medical history. She had taken care of her brother, who had Ebola, in the summer of 2014. She could have contracted Ebola from him at the time — she fell ill with symptoms that looked suspiciously like Ebola, but she was never tested. She recovered on her own.
She subsequently had a baby in September, became ill again in October, and then recovered once more. At that time she was tested for Ebola — twice — and the results were negative. Yet her system contained antibodies that develop when the body fights off an Ebola infection. She had what Fallah calls "the footprint of Ebola."
"We know she got exposed to Ebola because the antibodies are there," he asserts.
We spoke with Dr. Fallah about the possible role of the mother and other concerns in the investigation. The interview has been edited for length and clarity.
What do you know about the strain of Ebola that this family has?
Scientifically, it was not related to Sierra Leone's or Guinea's strain.
That [family's] strain's related to one of those local strains that was floating around Liberia last year.
Did the mother, who might have been carrying Ebola she contracted from her brother, infect her husband and sons?
All the information that we've gathered points to the mom. If that is true, we've got to answer the fundamental question: Is there a potential for people to become carriers [yet] they themselves don't get sick? Is it possible that the mother [somehow fought off] the virus [in her system] because she had antibodies but infected others?
Might the mom's pregnancy have somehow figured in?
If she got sick with Ebola last year, is it possible that [the virus] got reactivated because of her lowered immune system [due to her pregnancy]. But she did not develop Ebola [this year] because she already had antibodies.
So is sexual transmission from the mother to her husband a possibility?
We do know that there can be sexual transmission from male to female. We have never had a documented incident of a female to male. That's a key question we have to answer.
My gut feeling tells me there are some rare cases where it can be a female to male [transmission]. Some people don't agree with me; some tend to agree with me now.
Are there other possible sources for this family's infection?
We thought a relative may have come and given it to them. We tried to interview [possible nonmarital] sexual partners for the husband. Even close friends, we tested some. We don't see any leads.
Some people have thought: What if it's the 15-year-old boy who got it sexually from someone else?
We've been trying that also, we've tried to look at that. We've interviewed his social partners and everything.
If the virus was spread by the mother, are there other possible means of transmission besides sexual contact with the husband?
The family lives in one bedroom, uses one bathroom; they're a poor struggling family. They were taking care of each other. Somewhere [in the house] could be urine, vomit and someone could get [Ebola]. I think the day [the 15-year-old] went to the ETU [Ebola Treatment Unit], the mom was bathing him when he fainted.
This latest case must be a potential source of concern for survivors, who already are stigmatized because they had Ebola.
Every time I'm talking about survivors, I'm so careful. Because [information] can be taken out of context, and people can stigmatize survivors. That's the last thing I want to do.
The only good thing: At least I can say with assurance that any transmission from a survivor is a rare event — but high-consequence event.
Could some survivors remain highly contagious for many months?
We think that for some reason, the longer the [survivors] go, the [level of Ebola they may carry] is reducing and will end over a period of time.
Why do we say that? From the semen study in Sierra Leone — the [level of virus] in semen drops as the time passes.
What's an important lesson from your investigation so far?
The mistake is to assume we know everything about Ebola. I think it would be the worst mistake any of us in the Ebola field would make.