A Description Of Lassa Fever Mortality During The 2019 Outbreak In Nigeria

Background: Lassa fever (LF) is an acute zoonotic viral disease associated with high morbidity and mortality rates in hospitalized cases. LF is endemic in Nigeria with annual cyclical outbreaks. Previous studies estimate annual LF burden of 300,000–500,000 cases and 5000 deaths across West Africa with case-fatality-rate (CFR) of 15–25% among hospitalized patients and 50–60% during outbreaks. This study describes deaths in LF cases at treatment centres (TC) across Nigeria during the 2019 outbreak. Methods & Materials: Data was extracted from the National 2019 LF case fatality database. Variables such as patients’ demographics, duration of stay at treatment centres, pre-existing medical conditions and complications recorded prior to death were extracted and analyzed with descriptive statistics. Results: Between January and May 2019, Nigeria recorded 578 LF confirmed cases with 129 deaths (CFR 22.3%). Of the 129 deaths, 66 (51%) occurred at the treatment centres (TC). The median age was 38.5years (range 3 months–89 years), with a male to female ratio of 2:1. The median number of days from onset of symptoms to commencement of Ribavirin treatment in the TC was 7 (3–66) days, while median number of days from onset of illness to death was 12 (1–53) days. The median number of days between presentation at TC and death was 2 (0–49) days. 31% of patients reported Hypertension and Diabetes Mellitus as pre-existing conditions. Acute-Kidney-Injury was found to be the most common complication (23%). Conclusion: In the 2019 LF outbreak, 1 in 5 of the cases died, the majority of whom were of economically-active age group. The observed high Case Fatality Rate (CFR) may be due to delayed presentation to the treatment centre as majority of cases presented after 7 days of onset of symptoms. We recommend interventions to increase public awareness and encourage early presentation of LF cases to TCs.