Epidemiological Characteristics of Imported Malaria Cases Along the China-Myanmar Border - Yunnan Province, China, 2021-2025.

INTRODUCTION: In this study, the epidemiological characteristics of imported malaria cases (IMCs) along the China-Myanmar border in Yunnan Province (CMBYP) between 2021 and 2025 were analyzed, to provide a scientific basis for formulating effective measures to control imported malaria, prevent re-transmission, and consolidate malaria elimination achievements. METHODS: Individual data were collected from the National Notifiable Disease Reporting System for 2021-2025. The temporal, spatial, and demographic distributions of malaria cases, along with Plasmodium species, case classification, source of infection, and timeliness of medical treatment, were analyzed to describe the epidemiological characteristics. RESULTS: A total of 1,602 IMCs were reported in the CMBYP, with Plasmodium vivax accounting for 98.50% (1,578/1,602) of the cases. Of these, 75.97% (1,217/1,602) originated in Myanmar. The number of cases peaked between May and July. Demographically, 75.09% (1,203/1,602) of the patients were male, with a male-to-female ratio of 3.02∶1. All time intervals including those from onset to initial diagnosis and from the initial medical visit to malaria diagnosis were shorter in 2021-2022 than in 2023-2025. Additionally, 84.14% (1,348/1,602) of patients were correctly diagnosed at the initial medical visit. CONCLUSION: Summer is a critical period for the prevention and control of imported malaria. Strengthening case surveillance and vector control is essential for preventing importation and introduced transmission. There was an increasing trend in the number of IMCs, suggesting a potentially increased risk of transmission. However, a comprehensive assessment requires integration of malaria epidemic data from Myanmar. Malaria case surveillance is the core activity for malaria elimination, and for preventing the re-establishment of local malaria transmission.