In Nigeria, before 2017 the most recent case of human monkeypox had been reported in 1978. By mid-November 2017, a large outbreak caused by the West African clade resulted in 146 suspected cases and 42 laboratory-confirmed cases from 14 states. Although the source is unknown, multiple sources are suspected.

Background: Lassa fever is an acute viral haemorrhagic disease endemic in Nigeria. The 2018 Lassa fever outbreak in Nigeria was unprecedented, with 8% of all cases occurring among healthcare workers (HCWs). A disproportionately high number of these infections occurred in HCWs working in a tertiary health facility in Nigeria. This paper describes the cluster of Lassa fever infections among HCWs in a treatment centre and the lessons learnt. Methods: We analysed clinical, epidemiological and laboratory data from surveillance and laboratory records kept during the 2018 outbreak. Interviews were conducted with surviving HCWs using a questionnaire developed specifically for the investigation of Lassa fever infections in HCWs. Descriptive analysis of the data was performed in Microsoft excel. Results: The index case was a 15-year-old male who presented at the health facility with fever and uncontrolled nasopharyngeal bleeding, following a recent uvulectomy by a traditional healer. Overall, 16 HCWs were affected (15 confirmed and 1 probable) with five deaths (CFR-31.6%). Of the 15 confirmed cases, five (33.3%) were asymptomatic. Nine HCWs were direct contacts of the index case; the remaining six HCWs had no direct contact with the index case. HCW interviews identified a low index of suspicion for Lassa fever leading to inadequate infection prevention and control (IPC) practices as possible contributing factors to nosocomial transmission. Conclusion: Maintaining a high index of suspicion for Lassa fever in all patients, especially in endemic areas, is essential in adhering to adequate IPC practices in health facilities in order to prevent nosocomial transmission of Lassa fever among HCWs. There is a need to continually train and sensitise HCWs on strict adherence to IPC measures while providing care, irrespective of a patient's provisional diagnosis.

Process mapping is a systems thinking approach used to understand, analyse and optimise processes within complex systems. We aim to demonstrate how this methodology can be applied during disease outbreaks to strengthen response and health systems. Process mapping exercises were conducted during three unique emerging disease outbreak contexts with different: mode of transmission, size, and health system infrastructure. System functioning improved considerably in each country. In Sierra Leone, laboratory testing was accelerated from 6 days to within 24 hours. In the Democratic Republic of Congo, time to suspected case notification reduced from 7 to 3 days. In Nigeria, key data reached the national level in 48 hours instead of 5 days. Our research shows that despite the chaos and complexities associated with emerging pathogen outbreaks, the implementation of a process mapping exercise can address immediate response priorities while simultaneously strengthening components of a health system.

Nigeria Centres for Disease Control and Prevention established an event-based surveillance (EBS) system in 2016 to supplement traditional surveillance structures. The EBS system is comprised of an internet-based data mining tool and a call center. To evaluate the EBS system for usefulness, simplicity, acceptability, timeliness, and data quality, we performed a descriptive analysis of signals received during September 2017–June 2018. We used questionnaires, semistructured interviews, and direct observation to collect information from EBS staff. Amongst 43,631 raw signals detected, 138 (0.3%) were escalated; 63 (46%) of those were verified as events, including 25 Lassa fever outbreaks and 13 cholera outbreaks. Interviewees provided multiple examples of earlier outbreak detections but suggested notifications and logging could be improved to ensure action. EBS proved effective in detecting outbreaks, but we noted clear opportunities for efficiency gains. We recommend improving signal logging, standardizing processes, and revising outputs to ensure appropriate public health action.

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