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Summary Background Outbreak response efforts for the 2014–15 Ebola virus disease epidemic in west Africa brought widespread transmission to an end. However, subsequent clusters of infection have occurred in the region. An Ebola virus disease cluster in Liberia in November, 2015, that was identified after a 15-year-old boy tested positive for Ebola virus infection in Monrovia, raised the possibility of transmission from a persistently infected individual. Methods Case investigations were done to ascertain previous contact with cases of Ebola virus disease or infection with Ebola virus. Molecular investigations on blood samples explored a potential linkage between Ebola virus isolated from cases in this November, 2015, cluster and epidemiologically linked cases from the 2014–15 west African outbreak, according to the national case database. Findings The cluster investigated was the family of the index case (mother, father, three siblings). Ebola virus genomes assembled from two cases in the November, 2015, cluster, and an epidemiologically linked Ebola virus disease case in July, 2014, were phylogenetically related within the LB5 sublineage that circulated in Liberia starting around August, 2014. Partial genomes from two additional individuals, one from each cluster, were also consistent with placement in the LB5 sublineage. Sequencing data indicate infection with a lineage of the virus from a former transmission chain in the country. Based on serology and epidemiological and genomic data, the most plausible scenario is that a female case in the November, 2015, cluster survived Ebola virus disease in 2014, had viral persistence or recurrent disease, and transmitted the virus to three family members a year later. Interpretation Investigation of the source of infection for the November, 2015, cluster provides evidence of Ebola virus persistence and highlights the risk for outbreaks after interruption of active transmission. These findings underscore the need for focused prevention efforts among survivors and sustained capacity to rapidly detect and respond to new Ebola virus disease cases to prevent recurrence of a widespread outbreak. Funding US Centers for Disease Control and Prevention, Defense Threat Reduction Agency, and WHO.

Background Contact tracing is one of the key response activities necessary for halting Ebola Virus Disease (EVD) transmission. Key elements of contact tracing include identification of persons who have been in contact with confirmed EVD cases and careful monitoring for EVD symptoms, but the details of implementation likely influence their effectiveness. In November 2015, several months after a major Ebola outbreak was controlled in Liberia, three members of a family were confirmed positive for EVD in the Duport Road area of Monrovia. The cluster provided an opportunity to implement and evaluate modified approaches to contact tracing. Methods The approaches employed for improved contact tracing included classification and risk-based management of identified contacts (including facility based isolation of some high risk contacts, provision of support to persons being monitored, and school-based surveillance for some persons with potential exposure but not listed as contacts), use of phone records to help locate missing contacts, and modifications to data management tools. We recorded details about the implementation of these approaches, report the overall outcomes of the contact tracing efforts and the challenges encountered, and provide recommendations for management of future outbreaks. Results 165 contacts were identified (with over 150 identified within 48 hours of confirmation of the EVD cases) and all initially missing contacts were located. Contacts were closely monitored and promptly tested if symptomatic; no contacts developed disease. Encountered challenges related to knowledge gaps among contact tracing staff, data management, and coordination of contact tracing activities with efforts to offer Ebola vaccine. Conclusions The Duport Road EVD cluster was promptly controlled. Missing contacts were effectively identified, and identified contacts were effectively monitored and rapidly tested. There is a persistent risk of EVD reemergence in Liberia; the experience controlling each cluster can help inform future Ebola control efforts in Liberia and elsewhere., Author summary Contact tracing is one of the key response actions necessary for controlling spread of Ebola Virus Disease (EVD). Contact tracing is comprised of several different activities: identification of persons who have been in contact with confirmed EVD cases, close monitoring contacts for EVD symptoms, and management of symptomatic persons. Closely monitoring contacts of confirmed EVD cases allows for the rapid identification of symptomatic individuals, which in turn facilitates early testing, medical intervention, and isolation of new cases. This reduces the possibility of the continued spread of the virus within communities. Delayed and ineffective contact tracing contributed to the extensive transmission of EVD during the 2014–2015 outbreak in West Africa. Clusters of EVD reemergence are likely to occur, therefore understanding and addressing the challenges of implementing and managing contact tracing remains essential to halting transmission and minimizing morbidity and mortality associated with EVD. This paper assessed the contact tracing activities in response to EVD reemergence to identify best practices for responses to future Ebola clusters. The work is also applicable to contact tracing for other infectious diseases.

Background Intravenous artesunate reduces mortality by 35% relative to intravenous quinine. In 2010, WHO changed guidelines favouring intravenous artesunate, yet wide-scale adoption lags. In April, 2012, the Clinton Foundation with the Liberian Health Ministry brought intravenous artesunate into Liberia's busiest paediatric centres, Redemption and JDJ. The Foundation reached out to the International Rescue Committee, a non-governmental organisation that supported the hospitals, to implement the change. Methods We created a JDJ decision support instrument to guide and document proper intravenous artesunate administration. 4 months later, in July–October, 2012, we determined the proportion of children aged 1–16 years who were admitted for malaria with a positive rapid diagnostic test or malaria smear, the proportion who received intravenous artesunate, and the proportion who died. We compared these findings with the same period 1 year earlier when artesunate was not available. Findings From July to October, 2011, 707 patients were admitted to JDJ for malaria with 67 deaths, giving a mortality rate of 0·0950. 1 year later, 811 patients were admitted with 48 deaths, giving a mortality rate of 0·059—a decrease risk of 0·6455 (95% CI 0·4514–0·9231, p=0·0155). In 2011, no patients received intravenous artesunate, 650 (92%) intramuscular artemether, and 21 (3%) intavenous quinine. 1 year later, 632 (78%) of malaria patients received intravenous artesunate and 178 (22%) intramuscular artemether. Interpretation We show how malaria treatment can be changed quickly and effectively towards contemporary care standards. Our findings support the probable benefit of intravenous artesunate in Liberia and the need for the Ministry of Health to ensure artesunate supply and provider friendly treatment guidelines. Funding None.