I just watched, at a the Twin Cities Science Film Festival, a film called Nzara ’76, which is about the first known Ebola outbreak, the one that gave it its name, in southern Sudan. That’s about 150 miles, as the Mvo-Mvo flies, north of my long term project area in the Ituri Forest, an impassable distance over an unforgiving terrain if you are a person, well within the migratory range of an Ebola carrying fruit bat.

Back in the day, when Ebola would strike here and there, killing dozens, then disappearing back into the wild as quickly as it came, there was not much movement to get a vaccine. Then, one day, a fruit bat, carrying ebola, dropped some bat spit covered fruit bits to the ground, which were later picked up and mouthed by a toddler, who became patient zero in a pandemic that would ultimately kill over 11,000 people and sicken nearly 30,000. That would be a good argument to get a damn vaccine.

But, one could argue that even though Ebola is known to have been around since the 1970s, and may have been around before that (entire villages falling to a deadly disease is known historically in the region, with no understanding of what the disease was), it only arose as an epidemic once, so really, what’s the big deal? Next epidemic we’ll attack much more efficiently and quickly, and only hundreds, if that, will die.

Aside from the fact that the morbidity and mortality tolls in the tens of thousands should not inure us to the death of dozens or hundreds, we should also consider that the conditions that allowed this pandemic to occur arose only recently, so a pandemic is actually more likely in the near future than it was in the near past. Also, and this is from new research, now that Ebola has infected tens of thousands, it has a temporary reservoir in the post-infection population.

Research that could not have been conducted before has now been conduced (and is ongoing) in the pandemic region. It is now understood that survivors can have ebola in their systems for long periods of time after infection, and that in some cases, they can pass this on. It can be passed on through both breast milk and semen. I assume it could be passed on through blood.

It is simply NOT the case that thousands of post pandemic West Africans are restarting ebola epidemics wherever they go. Post pandemic transmission has been rare, and quickly managed. It is probably true that ebola will eventually leave all the post pandemic people. Humans are not really a reservoir, long term, for ebola.

But, consider the fruit bats. The story I gave above about the start of the pandemic is almost certainly true, but at the same time, fruit bats in the region came up empty when tested for Ebola. There are a lot of reasons that would happen, beyond the scope of this post, but it serves as a model for a near future West Africa. Perhaps ebola will last a long time in some individuals. Perhaps previously infected individuals will become reinfected, but not get sick, and be carriers for a year, or six months.

An ebola pandemic is not going to resurface easily, or form this source, in this population, because of post pandemic harboring. But, here and there, some people may get the disease, and if there is another outbreak somewhere else, we now know that the public health problems are even more complicated than previously thought.

The obvious way to solve this problem is with a good vaccine that is widespread and regularly administered.

The research I’m referring to hear was reported at a conference in Antwerp, Belgium, on September 12, and is briefly written up here, in Nature.

A few highlights, and a caveat, from that work:

Researchers will soon publish the first confirmed report of a person without obvious Ebola symptoms infecting another person. A seemingly healthy mother in Guinea passed the virus to her nine-month-old daughter in breast milk, and the child died from Ebola-virus infection in August 2015…

…some people who became infected during the recent outbreak escaped detection. Miles Carroll… tracked 80 people who had contact with Ebola patients in Guinea but did not themselves become noticeably ill. Yet 15–20% of these contacts developed immune responses capable of neutralizing Ebola viruses, suggesting that they had contracted mild infections that went undetected.

[Researchers] traced a cluster of new Ebola cases to a man who transmitted the virus to a sexual partner 17 months after recovering from his infection…

Researchers must show sensitivity in communicating such findings, says virologist Stephan Günther of the Bernhard Nocht Institute, and take care not to make life more difficult than it already is for Ebola survivors, who face discrimination and lingering health problems. “We have to be careful to stress that these are very, very rare events.”