Cases traced to Mabalako still fueling DRC Ebola outbreak

A known transmission chain from Ayola health zone in Mabalako, a town in North Kivu province of the Democratic Republic of the Congo (DRC), is linked to a resurgence of Ebola in Beni health zone, which hadn't seen an Ebola case in 29 days, and new cases in Musienene  health zone, where no cases had been reported for 132 days.

Both Beni and Musienene are also in North Kivu province.

The World Health Organization (WHO) described the transmission chain in its latest situation report on the outbreak, which covered the second week of January. Eight new cases were confirmed from Jan 6 to Jan 12, including three in Beni and one in Musienene.

"These four cases are linked to the transmission chain that originated in Aloya Health Area, Mabalako Health Zone, and were not unexpected given known links between Mabalako and Beni," the WHO said.

In the past 3 weeks, officials have confirmed 36 cases in 14 of 87 health areas in North Kivu and Ituri provinces. Mabalako accounted for 36% pf those cases, followed by Butembo (22%), Kalunguta (14%) Beni (8%), Katwa (6%), and Musienene (3%).

"Almost half (17/36) of these cases were isolated three or more days after symptom onset (including three community deaths), none of whom were known or being followed as contacts," the WHO said.

Three new cases today

The WHO's online Ebola dashboard shows 3 new cases today, raising the outbreak total to 3,406 cases, including 410 suspected cases still under investigation. There are still 2,235 fatalities, a number unchanged in recent days.

An update from the DRC's Ebola technical committee (CMRE) yesterday said 5 recent cases were from Mabalako (4) and Beni (1).

Vaccination efforts still continue throughout the outbreak region. As of yesterday, the CMRE noted 265,951 people have received Merck's rVSV-ZEBOV vaccine, and 5,684 people have been vaccinated with Johnson & Johnson's vaccine.

Profectus vaccine shown safe in phase 1 trial

In related news, a phase 1 trial of Profectus BioSciences' second-generation VSV VesiculoVax-vectored Ebola vaccine (rVSVN4CT1-EBOVGP1) demonstrated a solid immune response and good safety profile, according to a new study published yesterday in The Lancet Infectious Diseases.

The study was conducted on 39 healthy US adults. Profectus in 2015 showed the second-generation Ebola vaccine was safe and offered full protection against Ebola in monkeys. The second-generation vaccine is an intermediate and highly attenuated version of Merck's vesicular stomatitis virus (VSV) Ebola vaccine currently being used in the DRC.

That Merck vaccine, though highly effective, can cause self-limiting reactions. Profectus tested three different doses of its vaccine candidate on participants in a two-dose prime and boost regimen, and found that systemic adverse events occurred in 13 (33%) of 39 participants after the first dose and eight (21%) of 38 participants after the second dose. The events, though were mild (45 events) or moderate (11) in severity.

All participants showed an immune response to the Ebola virus by 42 days, and none reported arthritis or dermatitis, both of which have been linked to first-generation VSV vaccines.

"The study by Clarke and colleagues shows that potent immunity with a VSV-based vaccine against Ebola virus can be achieved while minimising adverse events," writes Marc-Antoine de La Vega, PhD, and Gary Kobinger, PhD, both of the University Laval in Quebec, Canada, in an accompanying commentary.

But they warn that long-term data on the immunogenicity of the Profectus vaccine are needed.

See also:

Jan 14 WHO situation report

WHO Ebola dashboard

Jan 14 CMRE report

Jan 14 Lancet Infect Dis study

Jan 14 Lancet Infect Dis commentary

Apr 8, 2015, CIDRAP News story "Second-generation Ebola vaccines show promise in animal study"

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