Tokyo: Ebola survivors can re-spread at least five years after infection and trigger an outbreak, and long-term follow-up of former patients is needed to prevent devastating flare-ups, according to new research.
Scientists already knew that Ebola could be dormant in survivors who test negative because the virus is in tissue rather than circulating in the blood.
But an analysis of an outbreak this year guineaPublished Wednesday in the journal Nature, these “virus reservoirs” were found to be able to awaken and cause years of new infections and transmission.
To trace the source of the Guinea outbreak, which included 16 confirmed cases, 12 of whom died, researchers analyzed the genomes of samples from several patients.
Ebola outbreaks are generally thought to result from the virus “spilling” from an animal host to a human.
But the analysis showed that the Guinea strain was almost identical to the 2013-16 wave.
If the virus had been actively circulating in the community since then, it would have accumulated a certain number of mutations as it spread.
Instead, the 2021 virus had only 12 changes, “much less than expected … during six years of continuous human-to-human transmission”.
This strongly suggests that the source was a reactivated virus lying dormant in a survivor, said alpha keeta, a researcher in Montpelier University who led the study.
“This is the longest known time between the declared end of a pandemic and a viral resurgence,” he told AFP.
“This is a new paradigm: the possibility that transmission from a person infected during a previous epidemic may be the source of a new outbreak.”
How and why a dormant Ebola virus suddenly wakes up and makes a person sick remains a mystery, although there are some tantalizing clues.
Sometimes a spike in Ebola antibodies can be detected in survivors over a given period of time – a possible sign that the body is responding to a resurgent virus.
About two-thirds of Ebola survivors still have high antibody levels five years after infection, but “the question is what happens if there is a relapse in people whose immunity has dropped”, Keita said.
The study’s findings have “substantial implications for public health and the care of Ebola survivors,” said Robert F. Gary of Tulane University’s School of Medicine.
“Humans can now be added to the list of intermediate hosts that can serve as long-term Ebola virus ‘reservoirs’ and trigger new outbreaks,” he said in a review commissioned by Nature. wrote.
He said there is a need to prioritize health workers for vaccination and monitoring Ebola survivors for signs of an outbreak.
Keita said a broader definition of “Ebola survivor” is now needed, beyond those who are struggling with symptoms.
Even asymptomatic individuals “can be starting points” for outbreaks, he warned.
“We need a real, long-term follow-up protocol … so that we can catch resurgence in people who are already infected in time.”
However, he cautioned that follow-up action should be done carefully to avoid exclusion of survivors, which is echoed by a point. trudy lang, director of Oxford University’s Global Health Network.
“These guys are considered heroes by some for the sake of survival,” she said.
“Yet (they) can also be stigmatized and ostracized if there is a fear of these individuals posing a risk.”
Lang, who was not involved in the study, said it offered “impressive new findings.”
The study shows “what we still don’t understand, but really need to learn, if we are to tackle these looming threats,” she said.
Going forward, Keita wants to see work on the causes of the viral resurgence and research on eradicating Ebola reservoirs in survivors.
“We have to look at Ebola as a global problem,” he said.
“Every person exposed to the virus who had a strong serological (antibody) response could be the starting point for a new resurgence.”
Scientists already knew that Ebola could be dormant in survivors who test negative because the virus is in tissue rather than circulating in the blood.
But an analysis of an outbreak this year guineaPublished Wednesday in the journal Nature, these “virus reservoirs” were found to be able to awaken and cause years of new infections and transmission.
To trace the source of the Guinea outbreak, which included 16 confirmed cases, 12 of whom died, researchers analyzed the genomes of samples from several patients.
Ebola outbreaks are generally thought to result from the virus “spilling” from an animal host to a human.
But the analysis showed that the Guinea strain was almost identical to the 2013-16 wave.
If the virus had been actively circulating in the community since then, it would have accumulated a certain number of mutations as it spread.
Instead, the 2021 virus had only 12 changes, “much less than expected … during six years of continuous human-to-human transmission”.
This strongly suggests that the source was a reactivated virus lying dormant in a survivor, said alpha keeta, a researcher in Montpelier University who led the study.
“This is the longest known time between the declared end of a pandemic and a viral resurgence,” he told AFP.
“This is a new paradigm: the possibility that transmission from a person infected during a previous epidemic may be the source of a new outbreak.”
How and why a dormant Ebola virus suddenly wakes up and makes a person sick remains a mystery, although there are some tantalizing clues.
Sometimes a spike in Ebola antibodies can be detected in survivors over a given period of time – a possible sign that the body is responding to a resurgent virus.
About two-thirds of Ebola survivors still have high antibody levels five years after infection, but “the question is what happens if there is a relapse in people whose immunity has dropped”, Keita said.
The study’s findings have “substantial implications for public health and the care of Ebola survivors,” said Robert F. Gary of Tulane University’s School of Medicine.
“Humans can now be added to the list of intermediate hosts that can serve as long-term Ebola virus ‘reservoirs’ and trigger new outbreaks,” he said in a review commissioned by Nature. wrote.
He said there is a need to prioritize health workers for vaccination and monitoring Ebola survivors for signs of an outbreak.
Keita said a broader definition of “Ebola survivor” is now needed, beyond those who are struggling with symptoms.
Even asymptomatic individuals “can be starting points” for outbreaks, he warned.
“We need a real, long-term follow-up protocol … so that we can catch resurgence in people who are already infected in time.”
However, he cautioned that follow-up action should be done carefully to avoid exclusion of survivors, which is echoed by a point. trudy lang, director of Oxford University’s Global Health Network.
“These guys are considered heroes by some for the sake of survival,” she said.
“Yet (they) can also be stigmatized and ostracized if there is a fear of these individuals posing a risk.”
Lang, who was not involved in the study, said it offered “impressive new findings.”
The study shows “what we still don’t understand, but really need to learn, if we are to tackle these looming threats,” she said.
Going forward, Keita wants to see work on the causes of the viral resurgence and research on eradicating Ebola reservoirs in survivors.
“We have to look at Ebola as a global problem,” he said.
“Every person exposed to the virus who had a strong serological (antibody) response could be the starting point for a new resurgence.”
.