Date Published: January 24, 2017
Publisher: Public Library of Science
Author(s): Mosoka P. Fallah, Laura A. Skrip, Philomena Raftery, Miata Kullie, Watta Borbor, A. Scott Laney, David J. Blackley, Athalia Christie, Emily Kainne Dokubo, Terrence Q. Lo, Stewart Coulter, April Baller, Benjamin T. Vonhm, Philip Bemah, Sowillie Lomax, Adolphus Yeiah, Yatta Wapoe-Sackie, Jennifer Mann, Peter Clement, Gloria Davies-Wayne, Esther Hamblion, Caitlin Wolfe, Desmond Williams, Alex Gasasira, Francis Kateh, Tolbert G. Nyenswah, Alison P. Galvani
Abstract: Alison Galvani and colleagues describe a community-based protocol to improve cooperation with Ebola testing as well as contact tracing, quarantining, and treatment.
Partial Text: On May 9, 2015, the World Health Organization (WHO) declared Liberia to be free of known Ebola virus transmission following a 14-month epidemic that resulted in nearly 4,800 deaths within Liberia alone . Since this declaration, three Ebola resurgences have occurred in Liberia (June 2015, November 2015, March 2016), and others have occurred in Sierra Leone (January 2016) and Guinea (March 2016). Whereas outbreaks of Ebola have been characterized by expansive transmission chains that disseminated over wide geographical scale, these resurgences were successfully contained as localized incidents in areas with recent history of widespread transmission. The risk of Ebola resurgences has been associated with increasing evidence of viral persistence in semen, breast milk, ocular fluid, and immunologically protected tissues during convalescence, with documented cases of sexual transmission from survivors [2–6]. This viral persistence combined with the sheer number (over 10,000) of Ebola survivors currently in West Africa poses a continued threat .
After 42 days of no known EVD transmission, Liberia shifted to a 90-day period of heightened surveillance in May 2015. During this period, the screening criteria for suspected cases of Ebola included febrile illness that did not respond to treatment, or sequelae clinically consistent with Ebola . Challenges (Box 1) to ETU-based diagnosis of individuals suspected of having EVD quickly became apparent. In June 2015, a man was reported to be vomiting by the community-based active case finders (ACFs) responsible for surveillance. An ambulance team was called to investigate and determine if he met the suspected case definition that would warrant ETU admission. Since the man was visiting from Guinea, where there was ongoing Ebola virus transmission, and since he was presenting with symptoms consistent with EVD, the team recommended that he be transported to the ETU for diagnosis. The individual suspected of having Ebola refused ETU admission, and his family threatened the ambulance team with violence. After the ambulance departed, the man fled with his family.
Traditionally, diagnosis of EVD involves real-time reverse transcription-PCR (RT-PCR) assays, which require 2 to 6 hours once a sample is received [21–24]. In 2015, the United States Food and Drug Administration and the WHO authorized emergency use of the Cepheid GeneXpert Ebola assay, a point-of-care diagnostic test that uses whole blood versus serum or plasma and accelerates results [26–28]. The sensitivity and specificity of the assay are comparable to those of the standard real-time RT-PCR, with enhanced sensitivity for the nucleoprotein target [21,26]. Specifically, compared to the benchmark Trombley real-time RT-PCR (rRT-PCR) assay for detection of the nucleoprotein of the Ebola virus , sensitivity and specificity on whole blood samples were found to be 100% (95% CI: 84.6%–100%) and 95.8% (95% CI: 91.8%–98.2%), respectively, for GeneXpert . The feasibility of implementing the technology, with its automated and closed-cartridge system for ease and safety, has been evaluated in an ETU in Guinea  and a field biocontainment laboratory in Sierra Leone .
In June 2015, positive samples from postmortem buccal swab and cardiac puncture prompted activation of an EVD response in Liberia’s Margibi County . When the response team arrived to investigate, contacts of the alert case refused referral to an ETU for diagnosis. Despite the positive EVD result from the body of the deceased, his contacts attributed his death to malaria. With the response team serving as facilitators, a subsequent discussion and negotiation then took place among the community leaders, key stakeholders, and the affected families who shared households with the 51 high-risk contacts. It was agreed that the high-risk contacts would cooperate with home-based blood draw and then admission to ETU in the event of positive diagnosis.
Following the success of the field diagnosis protocol in the first Liberian resurgence, it was again implemented in response to a November 2015 EVD cluster in a suburb of Monrovia. The alert case of this second resurgence was reported to the team by staff at a hospital where he sought care. The next morning, an extensive list was generated of over 165 contacts, who were visited in their homes twice daily by the response team to assess their temperature and the onset of any symptoms. Within 48 hours from the initiation of contact tracing, a contact became febrile but refused to be admitted to the ETU for diagnosis. Instead, field blood draw was conducted, and negative results were returned within 5 hours. As per the protocol, blood draw was repeated 48 hours later, and the results were negative again. A total of eight people underwent field blood draws, for which results were returned within 4 to 6 hours. Though the eight contacts had presented with EVD-like symptoms, the field blood draw results returned negative for all of them, eliminating the need for any ETU admission beyond the original case.
Point-of-care assays combined with field blood draw have the potential to accelerate diagnoses in emergency settings, where time is critical both for reducing Ebola transmission and improving prognosis. The feasibility of the point-of-care assay in a wider range of settings than is possible for more traditional methods and the rapidity of diagnostic results offer additional flexibility for responding to outbreaks of highly infectious diseases. This flexibility was fundamental to fostering cooperation with community members in EVD response efforts when ETU admission was associated with trauma, stigma, and potential nosocomial infection. Counter to initial fears, none of the phlebotomists, assistants, or household members became infected.