Ebola Virus Outbreak

Ebola Rates Plummet, But WHO Says More to Come

Doctor Francis Kateh (R) from Redemption Hospital volunteering to receive a trial vaccine against Ebola at Redemption Hospital on the outskirts of Monrovia. ZOOM DOSSO / AFP - Getty Images file

Ebola cases have plummeted in the three West African countries hit by the worst epidemic ever of the virus, but health officials say it’s not over yet.

More cases are likely to turn up in both Guinea and Sierra Leone, the World Health Organization says in its latest report on the epidemic. One patient disappeared in Guinea and is likely to have infected other people as she wandered across the border and visited a traditional healer, WHO said.

“In the week ending 2 August, two confirmed cases of Ebola virus disease were reported: one in Guinea and one in Sierra Leone. This is the second week in a row that weekly case incidence has been in single digits,” WHO says in a report released Wednesday.

"This is the second week in a row that weekly case incidence has been in single digits."

Liberia’s had no new cases in 21 days. The epidemic has infected nearly 28,000 people and is known to have killed more than 11,000 of them, with many deaths almost certainly unrecorded.

The good news: most of the new cases are contacts of known cases, which means health officials are tracking down most people at high risk of becoming infected.

And more good news – an experimental vaccine worked to protect people in Guinea against the virus and it will now be given to children.

“While the vaccine has, up to now, shown 100 percent efficacy in individuals, more conclusive evidence is needed,” WHO said.

Ebola game changer? 2:01

“The trial will now include 13- to 17-year-old and possibly 6- to 12-year-old children on the basis of new evidence of the vaccine’s safety.”

The bad news is people are still slipping through the cracks.

“Almost 2,000 contacts remain under observation across five prefectures in Guinea and four districts in Sierra Leone, and despite intensive efforts a small number of contacts in both countries have not been traced or have been lost to follow-up. In addition, recent high-risk transmission events in Guinea and Sierra Leone are very likely to result in further cases in the coming weeks,” WHO said.

"Over 40 contacts are considered to be at high risk of infection."

WHO described the case of the missing patient.

“The case, a 28-year-old woman, is a registered contact associated with a known chain of transmission that has given rise to several generations of cases in ... the capital, Conakry, over the past several weeks,” WHO said.

“After being lost to follow-up the case traveled south from Conakry through Forecariah and into Kambia, Sierra Leone, where she reportedly visited a traditional healer, before returning to Ratoma via Forecariah. Intensive efforts are underway to identify and trace all contacts in Guinea and Sierra Leone. “

Health workers are following up on more than 1,000 people.

And in another story that illustrates just how hard it will be to completely extinguish the virus, the latest case in Sierra Leone is one of more than 600 people who was contacted by a single patient.

“The new case is a family member who provided care to the index case. Over 40 contacts are considered to be at high risk of infection because of the nature of their contact with the index case, and there is a high probability that further cases will arise,” WHO said.