Risk of imported Ebola virus disease in China

Background: More than 600,000 annual arrivals from Africa, 1.4 billion population and developing health care systems render China at non-negligible risk of imported Ebola virus disease (EVD).

Method: According to the natural history of EVD, we constructed a deterministic SEIR model. Three published EVD outbreaks in Africa were enrolled to calculate the basic reproduction number (R0) of EVD. Scenarios representing unreported and reported (with n weeks delay) imported EVD in China were simulated to evaluate the effectiveness of interventions assumed to be implemented in different periods of the outbreaks.

Results: Based on previous Africa outbreak incidence datasets, our mathematical model predicted the basic reproduction number of EVD in the range of 1.53-3.54. Adopting EVD prevalence at 0.04-0.16% from the same datasets and estimated missing information and monitoring rates at 1-10%, a total of 6-194 imported cases were predicted. Be a single case left unidentified/unreported, total attack rate was predicted to reach 60.19%-96.74%. Curve fitting results showed that earlier intervention benefits in exponential and linear decrease in prevalence and duration of outbreak respectively.

Conclusion: Based on past outbreak experience in China, there is a need to implement an internet-based surveillance and monitoring system in order to reinforce health policy, track suspected cases and protect the general public by timely interventions.