Cluster of Ebola Virus Disease Linked to a Single Funeral — Moyamba District, Sierra Leone, 2014

Confirmed Cases of Ebola

Among 281 suspected Ebola cases in Moyamba District during July 11–October 31, a total of 109 (39%) were confirmed; among these patients, 40 died (case fatality rate = 37%). The median age of patients with suspected Ebola was 30 years (range = 11 months–84 years), and 59% were male. Incidence peaked during the week of September 13–19 at 32 confirmed cases (Figure 1). Overall, during the month before becoming ill, 78 (72%) patients with confirmed Ebola reported having contact with a known or suspected Ebola patient (alive or dead) or ill person. Forty-two (39%) had attended a funeral, 36 (33%) had carried or touched a corpse at a funeral, 10 (9%) had traveled, and eight (7%) had visited a hospital or traditional healer. Among 78 patients with confirmed Ebola who reported contact, 23 (29%) had contact with a corpse, 26 (33%) had contact with a live patient, and 29 (37%) had contact with an Ebola patient both while the patient was alive and after the patient had died.

Attendees at a Single Funeral

During September 5–7, 28 persons who were later confirmed to have Ebola attended the 3-day funeral of a prominent pharmacist in Moyamba; patients developed symptoms a median of 9 (interquartile range = 7–12) days after the funeral (Figure 2). The pharmacist was buried by relatives rather than by a district Ebola burial team, and his death was not investigated; consequently, no epidemiologic records exist regarding his exposures and illness, although anecdotal reports suggested he had treated an Ebola patient from a neighboring village. Among the 28 persons who attended the funeral and later developed Ebola, 23 (82%) were family members and 18 (64%) were male. Eight (29%) of these patients, all of whom were male and had touched the corpse, died and were buried by the district Ebola burial team. The case fatality rate among men was 44%; no deaths occurred among women (p = 0.02). Among the 28 Ebola patients who had attended the funeral, 16 (57%) reported having had direct contact with the pharmacist for days (August 25–September 1) before the funeral, and 21 (75%) carried or touched his corpse at the funeral. Subsequent contact with funeral attendees likely led to eight known additional confirmed cases (four in the second generation, including one death, and four in the third generation) (Figure 2).

Because the pharmacist was suspected to have died from Ebola, Moyamba DHMT engaged the local village chiefs, youth leaders, the community health officer, and others to ensure community support of rapid response measures. Moyamba DHMT conducted case investigations, traced contacts, and established quarantine in the town in mid-September 2014, closing local businesses and providing food support to residents for 21 days. District surveillance officers conducted daily active case finding. A youth leader convened a neighborhood watch, consisting of local, trained youths, who observed contacts of the pharmacist both inside and outside quarantine for Ebola symptoms every day, to support contact tracers and security. DHMT notified the community health officer to be on high alert for Ebola patients at the clinic or in the community; the community health officer notified DHMT soon after when children from the pharmacist’s home became symptomatic. Only two identified contacts of the pharmacist were lost to follow-up.

Discussion

A single, traditional funeral likely led to a sharp increase in Ebola cases in a previously low-incidence district in Sierra Leone, suggesting a substantially higher rate of secondary transmission from one patient than the basic Ebola virus reproduction number of 2.53 estimated for the outbreak in Sierra Leone (4). A high number of secondary cases might be explained by a high viral load in the primary patient, the type of contact, timing of contact (e.g., while a patient was alive or dead), the number of persons exposed, or a combination of these factors. An investigation of the 1995 Ebola outbreak in Kikwit, Democratic Republic of the Congo, identified 38 secondary cases linked to one patient who had many visitors while hospitalized (5).

Eight men with confirmed Ebola who attended this funeral died. The high case fatality rate among men might be explained by more intense or prolonged contact with the corpse by the male funeral attendees. According to traditional funeral practices in Sierra Leone, family and friends of the same sex are often responsible for preparing, washing, and clothing the body (6). Funerals pose a substantial risk for Ebola transmission for several reasons. First, the risk for transmission might increase with viral load, which is often highest in nonsurvivors, especially during the later stages of disease progression and at death (7). Second, the traditional practices of washing, preparing, and touching the body include direct, prolonged contact with the corpse. Finally, funerals attract family, friends, and colleagues from various locations. Attendance is important to demonstrate respect, establish land rights, and determine whether widows will return to their community of origin (6). Travelers who are exposed and become infected can establish new chains of transmission when they return to their original communities.

This report highlights the potential for high levels of transmission from a single patient or event and underscores the importance of vigilant Ebola surveillance and response. At least 36 Ebola cases and nine deaths might have been prevented had the pharmacist had a safe, medical burial. The DHMT’s comprehensive and targeted response, including rapid community engagement, quarantine, and active surveillance through daily house-to-house visits and formation of a youth neighborhood watch, likely led to the prompt identification of cases and limited transmission beyond the four cases in the second generation and the four cases in the third generation.

Fear, stigma, and discrimination might lead to underreporting of Ebola cases (8), and there was likely underascertainment of Ebola cases, deaths, and exposures. During the time of the investigation, Moyamba DHMT and CDC witnessed and received anecdotal reports of persons who were fleeing the area and hiding from surveillance and contact tracing teams. Self-reported data are limited by patients’ and proxies’ ability to recall exposures and dates, and social desirability bias and fear might have led to underreporting of Ebola symptoms and contact with ill persons or corpses.

To achieve and maintain zero new infections, enhanced community-based surveillance strategies, such as the community event-based surveillance system, which employs community health monitors to detect and report Ebola trigger events (e.g., two or more ill or dead family or household members) (9), are critical to the rapid identification of high-risk events to prevent transmission. Safe, dignified burials by trained burial teams using appropriate protective equipment are critical to the interruption of transmission and control of Ebola in both low-incidence and high-incidence settings, as well as in rural and urban settings (10). Early identification of Ebola cases along with prompt isolation, testing, and care of patients can limit transmission, improve likelihood of survival, and ensure safe burials of persons who die, ultimately preventing deaths from occurring at home and unsafe burials in the community. Ebola response teams can strengthen community Ebola surveillance.