Modelling the impact of interventions on imported, introduced and indigenous malaria infections in Zanzibar, Tanzania

Abstract

AbstractMalaria cases can be classified as imported, introduced or indigenous cases. The World Health Organization definition of malaria elimination requires an area to demonstrate no new indigenous cases have occurred in the last three years. Here, we present a malaria transmission model that incorporates human mobility and distinguishes between imported, introduced and indigenous cases. We test the impact of several interventions on Zanzibar such as reactive case detection, reactive drug administration, treating infected travellers, and transmission reduction on Zanzibar and mainland Tanzania. We find that the majority of new cases on both major islands of Zanzibar are indigenous cases, despite high case importation rates. Combinations of interventions that increase the number of infections treated through reactive case detection or reactive drug administration can lead to substantial decreases in malaria incidence, but for elimination within the next 40 years, transmission reduction in both Zanzibar and mainland Tanzania is necessary.