Global dynamics of a model of hepatitis B virus infection in a sub-Saharan African rural area

摘要

We formulate and systematically study a deterministic compartmental model of Hepatitis B.This model has some important and novel features compared with the well-known basic model in the literature.Specifically,it takes into account the differential susceptibility that follows the vaccine formulation employing three-doses schedule.It points up the HbeAg status of carriers,their levels of viral replication,the fact that treatment being not curative is recommended only to a small proportion of chronic carriers,and finally the fact that only inactive carriers are able to recover from disease.The model has simple dynamical behavior which has a globally asymptotically stable disease-free equilibrium when the basic reproduction number R0≤1 and an endemic equilibrium when R0>1.By the use of Lyapunov functions,when it exists,we prove the global asymptotic stability of the endemic equilibrium under some conditions.Using data from Tokombere,a rural area in Cameroon,numerical simulations are performed.These numerical simulations first confirm analytical results,second they suggest that a policy based on treatment could not significantly impact the course of the infection.Third,they show as it is well known that vaccination is a very effective measure to control the infection.Furthermore,they show that neonatal vaccination influences more the course of infection than mass vaccination strategy.Nevertheless,they picture how much loss between consecutive doses of vaccine could be harmful.Finally,it is suggested that for a Sub-saharan African rural area,two-thirds of expected incidence of Hepatitis B virus infection and one third of expected prevalence of chronic carriers could be averted by 2030 if the birth dose vaccination becomes systematic and if mass vaccination rate increases to up 10%.