Application of an Integrated Risk Matrix and the Borda Count Method on Lassa Fever in Assessing the Importation Risk of EID - 9 African Countries, 1996-2023.

INTRODUCTION

Common methods for assessing and responding to outbreaks of emerging infectious diseases (EIDs) are usually applied in isolation and have limitations. This study aimed to integrate the risk matrix and Borda count methods to assess the importation risk of EIDs to China, using Lassa fever (LF) as an example.

METHODS

This study used a mixed-methods approach combining multi-source data with an integrated risk matrix and Borda count method. Data were obtained from the World Health Organization, the Concise Statistics of International Students dataset, the United Nations World Tourism Organization, and the Statistical Yearbook. Importation risk was assessed across two dimensions: possibility and severity. Total importation risk was then categorized into 4 levels (low, moderate, high, and extremely high), corresponding to green, yellow, orange, and red zones, respectively, in the risk matrix assessment index. The Borda count method was used to rank the risks.

RESULTS

The importation risk for 9 countries that experienced LF outbreaks from 1996 to 2023 was scored and ranked by importation possibility and severity to derive overall importation risks. This study determined that Nigeria posed the highest LF importation risk to China, ranking first among West African countries with the highest Borda points. Countries with moderate importation risk included Sierra Leone, Burkina Faso, and Ghana.

DISCUSSION: An integrated risk matrix and Borda count method presented in this study may serve as a significant supplement to other risk assessment methods and enrich the current toolbox of public health countermeasures and inform future risk management of the importation of EIDs.