A hospital nurse checks the temperature of all visitors in Conakry (Guinea) in 2014, at the height of the Ebola epidemic. Marie-Agnès Heine/OMS, CC BY
The 2013-2016 Ebola epidemic in West Africa caused thousands of deaths - precisely 11,310, according to the World Health Organisation (WHO). But what happened to those who were infected, but survived?
In addition to those who died, the disease also infected more than 17,000 people who survived and were declared cured, at least officially. In the history of this newly emerging disease, this number of survivors is unprecedented in its scale.
The virus after the 'cure'
The Ebola virus was first identified in 1976, but scientists still have a lot to learn about the disease.
What happens to someone who has recovered from infection? What are the subsequent health impacts? Are they temporary or permanent? Is the virus definitively eliminated from the body, as in the flu, or may it reactivate one day, as with herpes? We are only now beginning to understand the answers to these and other questions.
Our research team conducted an intervention study with a large number of Ebola survivors: 802 out of the 1,270 identified in Guinea. We found that seven survivors in ten are affected by what we call "post-Ebola syndrome", a higher proportion than initially assumed.
The condition is characterised by several symptoms that can come and go, including severe fatigue, muscle and joint pain, head or stomach aches, neurosensory disorders such as dizziness or a loss in hearing, and an eye inflammation called uveitis (it affects the part of the eye called the uvea). These symptoms tend to decrease over time, suggesting that the majority of damage caused by the Ebola virus could be reversible.
Through this cohort, doctors will know how long survivors of an Ebola epidemic need to be followed for, and the standards of care they require.
A package of rice, but no medical follow-up
The project began with my arrival at the height of the epidemic, in September 2014, as a doctor and head of a research unit. I intervened at the request of the French Ebola taskforce. In the treatment centres, survivors were declared cured on a purely biological basis, after they had provided two negative blood tests for the virus.
Patients were then released with a "compassionate" kit, which consisted of a small sum of money and a package of rice. No medical follow-up was proposed.
On my return to Montpellier, France, I set up a team of French and Guinean researchers, including Mamadou Saliou Sow, a specialist in infectious diseases; the pharmacist and biostatistician Abdoulaye Touré; and the physician and biologist Alpha Kabinet Keita.
All are continuing the research project, working on the ground in Guinea. Until June 2018 at least, they are working with Ebola survivors to help manage the complications related to the disease.
Many symptoms, some severe
The good news at this point is that few post-Ebola syndromes take a severe form. We found only two cases of renal failure, one of which resulted in death. Eight people went blind as a result of inflammatory cataracts.
Doctors remain hesitant to operate on patients' cataracts because it isn't known how to eliminate the virus from the eye. There are also concerns that cataracts could recur in the absence of an antiviral therapy. Deafness occurred in one patient, a child, who was able to return to the school after being equipped with a hearing aid.
But scars left behind by Ebola are not only physical: 17% of the survivors studied suffer from depression. Given that they came close to death, and that many lost relatives, it's almost certainly post-traumatic syndrome, which requires dedicated care. One person committed suicide after surviving the disease.
To survive Ebola is also to confront the unfounded fear that former patients could pose a risk to those around them. In our study, 26% of survivors complain of feeling stigmatised. Anthropologists Desclaux Alice and Bernard Taverne worked with the same cohort of patients and found that some had lost their jobs, and a number of women were rejected by their husbands after returning home.
When Ebola returns
One crucial question is the risk of survivors falling ill again. This has already happened in Scotland and the US, with cases detected thanks to the more advanced health-care systems of industrialised countries. It is likely that similar cases have occurred in West Africa but were missed.
In 2014 a Scottish nurse developed the disease on her return from in Sierra Leone. Initially declared cured, nine months later she became ill with a meningitis resulting from persistence of the Ebola virus in her brain. After treatment with an experimental antiviral drug, she was again declared "cured".
The same year, an American physician was repatriated from the same country. After being declared "cured" he again exhibited declared symptoms, in particular an eye infection - the color of his irises had even changed from the blue to green.
Can the Ebola virus hide in "reservoirs" in the human body? Certain parts of the body, including the eye, the brain and the central nervous system, joint cartiledge and the testicles are called "immunologically privileged". They behave like fortresses that protect themselves from infection with a strong immune response. Their ramparts are difficult to cross for a disease, but once a virus manages to penetrate their defences, it can be difficult to dislodge.
In particular, sperm remains contaminated for up to 18 months after the acute phase of the disease. After this period, the virus disappears definitively and with it, any risk of transmission to a sexual partner.
For other parts of the body, the question of whether a virus might be able to reactivate later remains unanswered.
Staying with survivors
The WHO announced in December 2016 that an effective vaccine against Ebola had been developed, and with that, the men, women and children who survived the 2013-2016 epidemic began to fade from memory.
In the affected countries, most NGOs and aid organisations have shut down. Those that remain are often far removed from the daily lives of those who were affected. Public health systems in the areas hit by the disease are not in a position to take over.
But following survivors is vital to understanding how this terrible diseases affects people's health and communities, and help deal with any future outbreaks.