Shifting from control to elimination: analysis of malaria epidemiological characteristics in Tengchong County around China-Myanmar border, 2005-2014

Background: Tengchong County experienced a decreasing malaria prevalence period in 2005-2014 but the factors contributing to the trend are unclear. Herein, the malaria epidemiological data in years of 2005-2014 were collected and analysed, in order to provide evidence for subsequent effective strategic planning of malaria elimination that may be referenced by other counties with the similar elimination programmes along the China-Myanmar border. Methods: A retrospective study was conducted to explore malaria-endemic characteristics in years 2005-2014 in Tengchong County. All individual cases from a web-based reporting system were reviewed and analysed. Local infections and imported cases were obtained from an annual reporting system. Results: In total, 8321 confirmed malaria cases were recorded in this period, and 91.5 % of them were reported during 2005-2010. Plasmodium vivax was the major species (n = 5867, 70.5 %). Most cases (92.9 %) were found in males, mainly in the age group 30-34 years. Only five deaths resulting from Plasmodium falciparum were reported, of which three occurred in 2005. The cases were mainly reported in the townships of Wuhe (18.5 %), Mangbang (12.8 %) and Gudong (9.3 %). In addition, 147 local malaria (1.8 %) and 8174 imported malaria (98.2 %) were observed during 2005-2014. However, the proportion of imported malaria was more than 95 % all the time and no local transmission has been observed since 2013. Moreover, Myanmar was the main imported source, with 716 cases (94.6 %, 716/757) from Myanmar in 2011-2014. Conclusions: Tengchong County has made achievements in controlling malaria, with incidence at historically its lowest level. However, imported malaria has increased and poses a great threat to malaria elimination. To achieve the elimination goal and prevent the re-introduction of malaria, surveillance systems need to be well planned and managed to ensure timely case detection and prompt response targeted to the mobile and migrate population at elimination stage.