The cases were discovered after health officials investigated three mysterious deaths in a rural village. Four members of the family of the deceased are being tested for Ebola and two people, a mother and her 5-year-old son, have tested positive, the WHO said Thursday.
Teams of health workers, including epidemiologists, disease surveillance experts and vaccinators, are now arriving in the area in an effort to stop the virus before it spreads, WHO said. The Ebola outbreak that started in 2014 in West Africa killed more than 11,000 people and was the deadliest ever outbreak of the virus.
Experts say the new cases could point to a risk from the virus persisting in semen or other bodily fluid of survivors.
“WHO continues to stress that Sierra Leone, as well as Liberia and Guinea, are still at risk of Ebola flare-ups, largely due to virus persistence in some survivors, and must remain on high alert and ready to respond,” WHO said in a statement Thursday.
Dr. William Schaffner, an infectious disease expert at Vanderbilt Medical Center, said the virus could also have been persisted in rural areas unknown to health officials or it may have reappeared after transmission from wildlife. However, the mostly likely explanation is that the virus persisted in bodily fluids of a survivor, he said.
Schaffner said that experts are hampered by how little knowledge and information there is about how the virus affects and remains in the body of survivors.
"We think the Ebola virus is still out there lurking in some men, ready to start over," he said. "We don’t have an assessment of how many men are out there or how likely it is who can transmit it."
Genetic testing on the virus should offer clues about whether it is a brand new strain of Ebola or related to the strains from the 2014 outbreak, Schaffner said. He also pointed out that most of the population was not infected with the virus, which means they will not be immune if another outbreak occurs.
"The population continues to be very susceptible," Schaffner said. "You have to go back to square one and do all the same things all over again."