Monitoring Lassa Virus Prevalence in Nigeria Using Control Charts: A Public Health Surveillance Approach

In this study, Modified Exponentially Weighted Moving Average (MEWMA) chart is applied to monitor changes in the number of Lassa fever outbreak in Nigeria using the observed Lassa fever data obtained from Nigeria Centre for Disease Control (NCDC) website (https://ncdc.gov.ng/ diseases/sitreps). The designed structure is apply to demonstrate the application of the chart in the non-manufacturing area. From the evaluation, the chart has a good potential as a SPC tool for monitoring changes in the number of infectious diseases in Nigeria. The severity of each year considered was measured by the percentage number of points plotted outside of the upper control limit, 2023 (17.31%) > 2024 (2024) > 2025 (13.46%) > 2022 (9.62%) > 2021(7.69%). This severity, particularly pronounced around early weeks of the years, suggest that the occurrence of Lassa fever is influenced by seasonal or environmental factors, such as variations in rodent activity and climatic conditions favorable to virus spread. The observed periodicity highlights the disease’s cyclical nature and reinforces the need for sustained surveillance, preventive health education, and rapid response strategies during high-risk seasons to minimize the impact of recurrent outbreaks. The control charts enable early detection of weekly Lassa fever outbreaks, providing a systematic strategy for government and medical staff. Integrating the MEWMA chart for monitoring Lassa cases is recommended.