A CDC lab technician is being monitored for Ebola after possible exposure to what might have been live virus.

A small amount of material in a sealed plate was moved from a biosafety level-4 lab biosafety level-2 lab within CDC headquarters in Atlanta, the agency said in a statement Dec. 24.

Nevertheless, the CDC statement said, the material should not have been moved to the lower level lab. The agency said it can’t rule out the possibility a lab tech there was exposed.

The material was destroyed and the lower-level lab decontaminated as part of a routine procedures before the error was discovered Dec. 23, the CDC said, but the lab has been decontaminated again and closed; transfers from the level-4 lab have been halted during an internal investigation.

The technician has no signs of illness but will be monitored for 21 days, the incubation period of the virus.

In the statement, CDC Director Tom Frieden, MD, said he is “troubled by this incident in our Ebola research laboratory in Atlanta.”

He added he has ordered a full review of the incident, which comes after two highly publicized lapses in biosafety earlier this year — one involving anthrax and the other highly pathogenic H5N1 avian influenza.

“Thousands of laboratory scientists in more than 150 labs throughout CDC have taken extraordinary steps in recent months to improve safety,” Frieden said, adding: “no risk to staff is acceptable, and our efforts to improve lab safety are essential — the safety of our employees is our highest priority.”

Meanwhile, a report from the World Health Organization says that Ebola control measures have had “uneven” success — keeping the total incidence stable, while the geographic footprint of the epidemic grows.

In Guinea, Liberia, and Sierra Leone, the first week of December saw 625 confirmed or probable cases, the WHO Ebola Response Team reported online in the New England Journal of Medicine.

That’s similar to the average of 667 new cases weekly for the preceding 10 weeks, the investigators noted.

But the average is misleading, the investigators noted, because the places where incidence is greatest have changed over time.

For instance, in Guinea the incidence in Guéckédou, where the epidemic began, averaged 11 confirmed or probable cases weekly between March and September. But incidence in Gueckedou has fallen two cases a week since the beginning of October, while it has “increased sharply” in neighboring districts of Kerouané, Macenta, and N’zerekore, the investigators reported.

Similar geographic shifts have been seen in the other countries as well, they noted.

Indeed, in its midweek situation report, the WHO noted that Guinea had a record 156 confirmed cases in the week ending Dec. 21 — largely due to 58 cases in the province of Kissidougou, which had never before reported more than five a week.

In general, the midweek report said, reported case incidence is fluctuating in Guinea and declining in Liberia, while in Sierra Leone, there are hints that incidence may no longer be increasing.

In NEJM the WHO team wrote that it’s not clear why the overall numbers have stabilized, but one factor might be that infected people are getting into care more quickly.

When they compared the periods before and after Oct. 1, the average time from symptom onset to hospital admission fell from 5.3 days to 4.3 days, which might mean “a reduction in opportunities for transmission in communities.”

By Dec. 14, they noted, there were more than 2,000 beds available in Ebola treatment centers across the three countries — far in excess of the number of new patients being reported — although there were “substantial gaps” in treatment capacity in some places in each nation.

The evidence shows, they concluded, that the “worst fears” — continuing exponential growth — did not become reality. “Nevertheless, Ebola still presents a huge challenge as we move into the second year of the epidemic in West Africa,” they wrote.

Elsewhere in the Journal, investigators on the ground in Sierra Leone report that in their experience, the fatality rate from Ebola does not have to be as high as is commonly reported.

Overall, the WHO midweek report says, the reported case fatality rate in Guinea, Liberia, and Sierra Leone is about 70% among all cases for whom a definitive outcome is known.

And a case series reported in November, also from Sierra Leone, reported that 74% of patients were dying.

But in one clinic, the fatality rate was much lower, according to investigators led by Rashid Ansumana, MSc, of the Mercy Hospital Research Laboratory in Bo, Sierra Leone.

Analysis of 581 patients admitted to the Ebola treatment center at the Hastings Police Training School near Freetown after it opened Sept. 20 showed that just 183 died, they reported.

Patients were admitted, on average, within 3 or 4 days of symptom inset, they reported. Deaths usually occurred within 3 or 4 days of admission, while survivors usually were in hospital for about 2 weeks.

“It is unclear why the case fatality rate is decreasing at Hastings,” the investigators admitted, noting that they can’t single out any particular component of their protocol.

The treatment protocol, Ansumana and colleagues reported, includes antibiotics (ceftriaxone and metronidazole) for 72 hours as well as fluid replenishment with Ringer’s lactate and dextrose saline. Patients also get vitamin K and an antimalarial drug on admission, as well as zinc sulfate tablet daily, ibuprofen every 12 hours, and metoclopramide intravenously as needed for nausea or vomiting.

After the first 3 days, therapy includes more antibiotics and anti-malarials, as well as a nutrition supplement and oral rehydration solution and juice drinks.

The WHO reported that the West African epidemic has now caused some 19,695 confirmed, probable, or suspected cases, with 7,693 deaths.