A genetic analysis of virus samples from Guinean patients suggests that the new outbreak is a continuation of the 2014-16 outbreak.
According to scientists, the Ebola outbreak now affecting Guinea was almost certainly started by someone who survived West Africa’s historic 2014-16 epidemic, harbored the virus for at least five years, and then transmitted it via semen to a sex partner.
Based on genetic sequencing of virus samples taken from patients in the current outbreak, researchers were shocked by the discovery. It was previously known that the virus could persist in a survivor for 500 days.
According to Doctor, an infectious-disease expert at Vanderbilt University who was not involved in the study, “it’s a stunner.” A phenomenon of this magnitude has never been seen before.
At least 18 people have been infected and nine have died as a result of the current outbreak in Guinea, which was first recognized in January.
It has profound implications to discover that a survivor most likely started the outbreak. A previous epidemic in West Africa infected more than 28,000 people, killed more than 11,000 and left thousands of survivors, some of whom were already shunned because of fear of the disease. As a result, those who survive might be infectious for years, further worsening their situation.
Also, other outbreaks in the region, thought to have begun with transmission from animals, may actually have started by survivors with unrecognized, lingering infections.
Doctor said that one solution would be “to vaccinate much of equatorial Africa” against Ebola. Merck and Johnson & Johnson manufacture effective vaccines, but to date they have been used only in response to outbreaks.
The virus is eradicated by the immune system when people recover from Ebola. The immune system cannot attack certain parts of the body, such as the eye, the central nervous system, and the testes. It is possible for the virus to hide in those places sometimes. However, no one knew it could hide for so long.
“We do not know how often this happens,” Doctor said. Several studies are being conducted. However, studying hidden viruses in immunologically privileged sites, such as the testicles, the eye, and rarely, the central nervous system, is not easy.
According to researchers, the genetic sequences of virus samples from the current outbreak are so similar to those from the 2014-16 outbreak that they must be closely related. Researchers from the Guinea Ministry of Health, other labs there, Senegal’s Pasteur Institute, the University of Edinburgh, the University of Nebraska Medical Center, and PraesensBio collaborated on Friday’s report.
Science and Statistics reported the findings earlier on Friday.
“There are very few genomic changes, and for those to occur, the virus must multiply,” Schaffner said. “I believe the virus is mostly in hibernation.”
Among other things, it shows what brilliant insights whole genome sequencing can provide. All of us thought that the current outbreak was caused by transmission from nature, from bats. It is likely to have come from a human reservoir.”
Wiley, a virologist at the University of Nebraska Medical Center and the chief executive of PraesensBio, which provided the samples, characterized the current outbreak as a “continuation” of the previous one.
According to him, persistent infections and sexual transmission were already recognized during outbreaks in West Africa and the Democratic Republic of Congo. He said each new milestone for viral persistence came as a shock: 180 days, 500 days, and now more than five years later.
Thomas Skinner, a CDC spokesman, stated: “CDC has reviewed the sequencing data from samples taken during the current outbreak in Guinea. In spite of the fact that we cannot be 100 percent certain, CDC agrees that there are likely links between the current outbreak and the West Africa Ebola outbreak of 2014-2016.”
He explained: “This suggests that the outbreak was likely caused by a persistent infection, a survivor, rather than a new introduction of the virus from an animal reservoir.”. In spite of the fact that outbreaks in the Democratic Republic of Congo have been linked to survivors, the length of time it took between the end of the 2014-2016 outbreak and the emergence of this outbreak is surprising, and underscores the need for further research to better understand Ebola’s complex epidemiology and ecology.”
According to Doctor, a virologist at Columbia University, when male patients have several semen samples that test negative for Ebola, they are generally deemed to have cleared the virus, but that isn’t always the case.
“Those who have had Ebola should probably be monitored regularly to ensure they remain negative,” he said.