Epidemiological characteristics of imported malaria in China, 2011–2016

ObjectiveTo understannd the epidemiological characteristics of imported malaria in China during 2011—2016 and provide scientific evidence for the improvement of malaria surveillance and reaching the goal of elimination of malaria by 2020 in China.

MethodsThe data of laboratory confirmed imported malaria cases from 2011 to 2016 were obtained from the Information System of Chinese Center for Disease Control and Prevention and analyzed with software SPSS and ArcGIS.

ResultsA total 18 385 imported malaria cases, including 117 deaths, were reported in China during this period. Up to 94.87% of fatal cases were imported from Africa, and falciparum malaria accounted for 96.58%. The average interval between onset and diagnosis of falciparum malaria fatal cases (6.92 d) was longer than that of those who survived (4.93 d) (F＝15.21, P＜0.001). Imported cases were reported all the year round. The cases were mainly males (94.57%), aged 26–45 years (60.92%) and migrant workers (70.82%). The cases were mainly from Africa (72.98%) and Asia (24.87%, mainly from Myanmar). Africa imported cases were mainly from Ghana (16.70%), Angola (14.44%), Nigeria (11.58%), and Equatorial Guinea (10.79%). The proportion of Africa imported cases increased obviously from 48.71% in 2011 to 84.02% in 2016, in which 1 333 cases were from Ghana in 2013. The imported areas were mainly detected in Yunnan (18.43%) and Guangxi (12.55%). The imported malaria cases were mainly falciparum malaria and vivax malaria in China. The proportion of vivax malaria decreased from 43.81% to 21.46%, while the proportions of falciparum malaria, quartan malaria and ovala malaria increased from 52.71%, 0.67% and 0.63% in 2011 to 65.25%, 2.15% and 10.47% in 2016, respectively.

ConclusionThe annual proportion of falciparum malaria increased rapidly in imported malaria cases in China, which might be attributed to the increase of imported malaria cases from Africa. It is suggested take labor export population to malaria endemic areas as key surveillance population and improve falciparum malaria diagnosis to reduce malaria related death and prevent secondary transmission.