SUMMARY
There were 2 confirmed cases of Ebola virus disease (EVD) reported in the week to 20 September, both of which were in Guinea. Case incidence has remained below 10 cases per week since the end of July this year. Over the same period, transmission of the virus has been geographically confined to several small areas in western Guinea and Sierra Leone, marking a transition to a distinct, third phase of the epidemic. Improvements to rapid and accurate case investigation and contact tracing, rapid isolation and treatment, and effective engagement with affected communities have all played a crucial part in reducing case incidence to its current low level. A refined phase-3 response1 coordinated by the Interagency Collaboration on Ebola2 will build on these existing measures to drive case incidence to zero, and ensure a sustained end to EVD transmission. Enhanced surveillance capacity to rapidly identify a reintroduction (either from an area of active transmission or from an animal reservoir), or re-emergence of virus from a survivor, improved testing and counselling capacity as part of a comprehensive package to safeguard the welfare of survivors, and the increased use of innovative technologies—from vaccines to rapid diagnostic tests—are central to the phase-3 response framework. Accordingly, an increased emphasis will be placed on the monitoring and evaluation of these additional phase-3 measures in the coming weeks.
After recording 14 consecutive days with zero confirmed cases, two new confirmed cases were reported from Guinea during the week ending 20 September: a 10-year-old girl who died after moving from the Ratoma area of Conakry to Forecariah, and a 24-year-old woman who was identified as EVD-positive in the Dixinn area of Conakry. Neither case was a registered contact, although both cases have a strong epidemiological link to a probable case thought to have died from EVD at the end of August. Investigations incorporating genetic sequencing of Ebola virus from both confirmed cases suggest they are part of the Ratoma chain of transmission—the only chain of transmission known to be currently active (past 21 days) in Guinea.
No new confirmed cases were reported from Sierra Leone in the week to 20 September. Over 700 contacts have been identified in association with the previous week’s reported case from Bombali: a 16 year-old girl identified as EVD-positive after post-mortem testing. Investigations into the origin of her infection have not yet concluded, but preliminary findings suggest that a survivor may have been the source.
Robust surveillance measures are essential to ensure the rapid detection of any reintroduction or reemergence of EVD in currently unaffected areas. A total of 719 samples were tested by 8 operational laboratories in Guinea in the week to 20 September. Analyses of the geographical distribution of samples collected indicate that 21 of 34 Guinean prefectures did not collect any samples from either live or dead suspected cases of EVD over the 1-week period. Over the same period, 1887 samples were collected from 100% (14 of 14) of districts in Sierra Leone and tested by 9 operational laboratories. In Liberia, 1435 samples were collected from 100% (15 of 15) of counties in the week to 20 September, although the capacity of the country’s 3 operational laboratories is not currently sufficient to rapidly test all samples. Surveillance in the three countries will be enhanced in line with the phase-3 response framework.