Epidemiological characteristics of imported malaria in Shandong Province, China, from 2012 to 2017

Shandong Province, China, has been implementing a malaria elimination program. In this study, we analyzed the epidemiological characteristics of malaria imported into Shandong Province between 2012 and 2017 to provide scientific data for the elimination of malaria. In this epidemiological study, we examined the status of malaria in 2012-2017 in Shandong Province, China. Data on all cases of malaria were collected from the online Infection Diseases Monitor Information System to describe and statistically analyze the sources of infection, species of parasite, populations affected, regional distributions, incidence, and temporal distributions of malaria. In total, 1053 cases of malaria were reported in 2012-2017, and all of them were imported. Plasmodium falciparum was the predominant species (77.6%) in Shandong Province; P. vivax malaria accounted for 10.9% of the total number of cases, P. ovale malaria for 2.9%, and P. malariae malaria for 8.2%. Most patients were male (96.8%), most were aged 21-50 years (87.2%), and migrant laborers (77.2%) and workers (6.6%) were at highest risk. The origin of the largest number of imported cases was Africa (93.4%), followed by Asia (5.9%) and Oceania (0.4%). Most cases of imported malaria occurred in June each year and 70% of cases were recorded in six cities during the period of 2012-2017. It is necessary to strengthen malaria surveillance among workers returning home from Africa and Southeast Asia, and to conduct timely blood tests to diagnose and treat imported infections.