Ebola, still with us?

Patients who are still suffering more than 4 years after their recovery, and a virus that plays hide-and-seek with our immune system. This is the aim of the work carried out by Alpha Keita and Eric Delaporte with the TransVIHMI and CERFIG teams, which has highlighted a real paradigm shift in the transmission of the Ebola virus.

IRD - Alain Tendero, Post Ebogui 2018

It's a word that sounds like the title of a B-movie disaster: Ebola. A disease that fires the imagination of screenwriters, but weighs heavily on the daily lives of thousands of people. And it can affect them for much longer than previously thought. This is what physician Eric Delaporte and virologist Alpha Keita, researchers at the TransVIHMI laboratory, have discovered. For more than four years, they have been following 722 survivors of the major Ebola epidemic that took place in West Africa between 2013 and 2016. Declared cured "meaning that no virus was found in their blood", explains Alpha Keita, some of them are still suffering from after-effects, more than 4 years after their recovery.

Ebola long

This cohort of patients, called PostEboGui, was closely monitored by researchers from IRD, Inserm, the University of Montpellier, the University of Conakry and Cerfig (Centre de recherche et de formation en infectiologie en Guinée), who found symptoms in 1 in 3 patients. Headaches, dizziness, fever, fatigue, anorexia, abdominal or musculoskeletal pain, anxiety, depression... the list of symptoms of what researchers now consider a "long Ebola" - by analogy with the long Covid - is just as long.

There are several types of symptoms," explains Eric Delaporte. They can be linked to a post-traumatic syndrome, or directly to the attack of the virus and the damage it has caused to the organism". But they can also be caused by the virus nestling in particular areas of the body, such as the eye, joints or brain, where it persists long after recovery, causing chronic inflammation responsible for long-term pain. "These are what we call places of immune privilege, because they're places where antibodies don't come into play," explains Eric Delaporte.

Immune hide-and-seek

Well protected, the Ebola virus can therefore persist for years in the body... And emerge from its hiding place whenever it pleases? In any case, this is what may have given rise to the new Ebola epidemic in Guinea in February 2021. To find out the origin of this new epidemic, researchers analyzed the genome of the virus taken from patients and obtained some surprising results. " We found that it was very similar to the one that caused the epidemic that ended in 2016, so the 2021 epidemic was caused by the resurgence of a persistent source, most likely a human host in which the virus had remained hidden all this time", adds Alpha Keita.
This represents a real paradigm shift for researchers, since "for a long time, it was thought that with each new epidemic, the virus was introduced into the population via contact with wild fauna, thus passing from animals to humans", explains Eric Delaporte.

The virus, safely ensconced in these viral reservoirs, could cause a relapse years later in a patient considered cured. It could even be transmitted by these "healthy carriers" to other individuals, who would then declare the disease. "The testicles are another site of immune privilege, so Ebola can be transmitted sexually. We have already documented a case where a survivor evidently transmitted the virus to his partner via semen, months after he had been declared cured", adds Eric Delaporte.

Stigmatization

These revelations - while shedding new light on these epidemics - must be treated with great caution, according to the researchers. None of this allows us to affirm that it is precisely an Ebola survivor who is at the origin of this new epidemic," they warn. It could well have started from an asymptomatic patient". This is a vital clarification, given that Ebola survivors are already victims of stigmatization: "they can lose their jobs, their homes, they are sometimes even rejected by their communities, a stigmatization that risks being further exacerbated if we communicate poorly on this issue", Eric Delaporte points out. "In Guinea, 16% of individuals have antibodies against Ebola. As far as we know, everyone can consider themselves to be the starting point of this epidemic", concludes Alpha Keita.
In any case, these unprecedented results call for Ebola patients to be supported long after their recovery. "Long-term sequelae can have a major negative impact on survivors' health, quality of life and ability to work. It is important to continue to monitor them over the long term, not only to improve their care but also to prevent any resurgence of the virus," concludes Eric Delaporte.