Abstract

Modeling the Lassa Fever Outbreak Synchronously Occurring with Cholera and COVID-19 Outbreaks in Nigeria: a Threat to Global Health Security

Nancy B Tahmo, Frankline S Wirsiy, David M Brett-Major, College of Public Health, University of Nebraska Medical Center

APHA 2022 Annual Meeting and Expo

Nigeria, long before the COVID-19 pandemic and ongoing Cholera epidemic struggled with seasonal outbreaks of Lassa fever (LF) with about 72%-100% of its States affected annually. With the pandemic, the already-strained health system prioritized some public health threats and Lassa fever cases went up 46.8% in 2020 (1189), most of which were asymptomatic.
This study employed a Poisson regression model using data from epidemiologic week 1 to week 52 in 2021 to assess if COVID-19 and Cholera case numbers are predictors of Lassa fever disease incidence, including the number of States affected and the month of the year. The significant predictors were applied to forecast the progression of the Lassa fever outbreak using a Seasonal Autoregressive Integrated Moving Average (SARIMA) model.
The Poisson model prediction for the confirmed number of Lassa fever cases was significantly dependent on the number of confirmed COVID-19 cases, the number of States affected, and the month of the year (p-value < 0.001) and was not significantly dependent on the reported suspected cholera cases (p-value=0.237). The SARIMA model was a good fit, accounting for 48.1% of the change in the number of cases of Lassa fever (p-value < 0.001) with parameters ARIMA (6, 1, 3) (5, 0, 3).
Early in 2022, some cases of LF were identified in the UK; these results demonstrate the importance of strengthening health systems in resource-poor countries to prioritize and concurrently address more infectious diseases.

Keywords: Lassa fever, syndemic epidemic, Nigeria, co-infection, modeling, health security