Survivors of the Ebola virus can cause outbreaks years after they were infected.
According to new research, Ebola survivors can relapse and cause epidemics up to five years after infection, and long-term follow-up of former patients is required to prevent deadly flare-ups.
Ebola could stay dormant in survivors who test negative because the virus is in tissue rather than circulating in the blood, according to scientists.
However, according to a study published in the journal Nature on Wednesday, these “virus reservoirs” can reawaken and produce fresh infections and transmission years later.
Researchers examined the genomes of samples from many patients to determine the source of the Guinea outbreak, which had 16 confirmed cases and 12 deaths.
In most cases, Ebola epidemics are assumed to be the result of the virus “spilling” from an animal host to a human.
The Guinea strain, however, was found to be nearly identical to one from the 2013-16 wave, according to the research.
If the virus had been circulating in the population since then, it would have picked up a number of modifications along the way.
Instead, the virus in 2021 had only 12 mutations, “far less than would be predicted… during six years of sustained human-to-human transmission,” according to the researchers.
According to Alpha Keita, the study’s lead researcher at the University of Montpellier, this clearly suggests the cause was a reactivated virus that had been dormant in a survivor.
“This is the longest interval known between an epidemic’s announced conclusion and a viral resurgence,” he told AFP.
“It’s a new paradigm: the prospect that an individual who was infected during a previous epidemic could be the cause of a fresh outbreak.”
Though there are some tantalizing indicators, how and why the dormant Ebola virus unexpectedly emerges and sickens a person remains a mystery.
In certain survivors, a spike in Ebola antibodies can be discovered at a specific time, which could indicate that the body is responding to a resurgent infection.
Even five years after infection, two-thirds of Ebola survivors have strong antibody levels, but “the issue to pose is what happens if there is a resurgence in the people whose immunity has dropped,” said Keita.
According to Robert F. Garry of Tulane University’s School of Medicine, the findings of the study have “significant ramifications for public health and care of Ebola survivors.”
In a review commissioned by Nature, he said, “Humans can now be added to the list of intermediary hosts that can act as long-term Ebola virus’reservoirs’ and spark fresh epidemics.”
He believes that healthcare personnel should be prioritized for immunization and that Ebola survivors should be monitored. Brief News from Washington Newsday.