SUMMARY
There were 2 confirmed cases of Ebola virus disease (EVD) reported in the week to 6 September: 1 in Guinea and 1 in Sierra Leone. Overall case incidence has remained stable at 2 or 3 confirmed cases per week for 6 consecutive weeks. There are a total of three active chains of transmission—two in and around Conakry, Guinea, and one in the western district of Kambia, Sierra Leone—after all remaining contacts associated with transmission chains in Forecariah, Guinea, completed follow-up in the week to 6 September. In addition, Liberia was declared free of Ebola virus transmission in the human population for a second time on 3 September 2015, 42 days after the country’s last laboratory-confirmed case associated with the Margibi cluster of cases completed treatment and was confirmed as EVD-negative. Liberia has now entered a 90-day period of heightened surveillance. The total number of contacts under observation in Guinea and Sierra Leone has increased from approximately 450 on 30 August to approximately 1300 on 6 September. This increase is largely attributable to the single high-risk community death reported from Kambia, Sierra Leone, at the end of the previous week (week to 30 August). Both cases reported in the week to 6 September were registered contacts associated with previous cases in the same areas of Conakry, Guinea, and Kambia, Sierra Leone, in the past 2 weeks. The case reported from Guinea is considered to present a high risk of further transmission.
There remains a risk of short-term increases in case incidence as a result of these high-risk cases.
The single confirmed case reported from Guinea in the week to 6 September had onset of symptoms in the Ratoma area of the capital, Conakry. The case is a 13-year-old girl, and is a registered contact and relative of 2 cases reported from the same area of the city during the previous 2 weeks. She is considered to present a high risk of further transmission after she was briefly lost to follow-up after developing early symptoms. She then presented to several private health facilities whilst symptomatic before being traced, tested for EVD and admitted to an Ebola treatment centre. The 292 contacts under follow-up on 6 September in Guinea were located in 2 adjacent prefectures, Conakry (266 contacts) and Dubreka (26 contacts). The last remaining contacts in the prefecture of Forecariah completed follow-up in the week to 6 September.
One new confirmed case was reported from Sierra Leone in the week to 6 September. The case is the daughter of the high-risk case reported from Kambia in the previous week (week to August 30): an approximately 60-year-old woman identified as EVD-positive after post-mortem testing in the village of Sella Kafta, Tonko Limba chiefdom. The most recent case was identified as a high-risk contact after caring for her mother during the course of her mother’s illness. Over 900 contacts have been identified in association with the chain of transmission, although the majority of these contacts have been defined by geographical proximity rather than by history of possible exposure, and are therefore considered to be at very low risk. However, further cases are expected among the approximately 40 high-risk contacts identified so far. The origin of infection of the 60-year-old woman remains under investigation.
No new health worker infections were reported in the week to 6 September. There have been a total of 881 confirmed health worker infections reported from Guinea, Liberia, and Sierra Leone since the start of the outbreak, with 513 reported deaths