Origin of malaria cases: a 7-year audit of global trends in indigenous and imported cases in relation to malaria elimination

BACKGROUND: Countries in the different stages of pre-elimination, elimination, and prevention of reintroduction are required to report the number of indigenous and imported malaria cases to the World Health Organization (WHO). However, these data have not been systematically analysed at the global level. OBJECTIVE: For the period 2007 to 2013, we aimed to report on 1) the proportion of countries providing data on the origin of malaria cases and 2) the origin of malaria cases in countries classified as being in the stages of pre-elimination, elimination and prevention of reintroduction. DESIGN: An observational study using annual data reported through routine health information systems to the WHO Global Malaria Programme between 2007 and 2013. RESULTS: For all countries classified as being in pre-elimination, elimination, and prevention of reintroduction in the year 2013, there has been a substantial decrease in the total number of indigenous malaria cases, from more than 15,000 cases reported in 2007 to less than 4,000 cases reported in 2013. However, the total number of imported malaria cases has increased over that time period, from 5,600 imported cases in 2007 to approximately 6,800 in 2013. CONCLUSIONS: Vigilant monitoring of the numbers of imported and indigenous malaria cases at national and global levels as well as appropriate strategies to target these cases will be critical to achieve malaria eradication.