Abstract:

To understand the epidemiological characteristics of malaria in Dalian City, so as to provide insights into prevention of re-establishment of malaria after elimination. Data pertaining to epidemiological individual investigations of reported malaria cases in Dalian City from 2014 to 2023 were retrieved from the National Information System for Infectious Diseases Surveillance and National Information System for Parasitic Diseases Control and Prevention, and the epidemiological features of reported malaria cases were analyzed using descriptive and analytical epidemiological methods. A total of 125 malaria cases were reported in Dalian City from 2014 to 2023, and all were overseas imported cases, including 2 deaths. Among all reported cases, falciparum malaria accounted for 85.6% (107/125), ovale malaria accounted for 10.4% (13/125), quartan malaria accounted for 3.2% (4/125) and vivax malaria accounted for 0.8% (1/125). The annual average number of reported malaria cases was 12.5 in Dalian City from 2014 to 2023, with the highest number of reported cases in 2017 (25 cases). Malaria cases were reported across all months, and the highest number of malaria cases was reported in January (16.0%, 20/125), without seasonal variations. Malaria cases were detected in permanent residents across all counties (districts) in Dalian City, with the highest number of cases seen in Ganjingzi District (18.4%, 23/125), and the reported malaria cases acquired infections from 20 countries in Africa, and the country where the highest number of malaria cases acquired infections was Nigeria (13.6%, 17/125). The male-to-female ratio of reported malaria cases was 10.36 : 1, and the reported cases had a median age of 42 years, with the highest number of reported cases at ages of 30 to 39 years (28.0%, 35/125). Of all reported malaria cases, junior high school was the predominant educational level (39.2%, 49/125), and worker was the predominant occupation (31.2%, 39/125). The median interval from returning to China to disease onset was 7 days and the median duration from disease onset to diagnosis was 4 days among reported malaria cases. Among all reported malaria cases, there were only 6 cases (4.8%) with definitive diagnosis within 1 day from disease onset, and 30 cases (24.0%) with definitive diagnosis exceeding 7 days from disease onset, and there were 110 cases (88.0%) with definitive diagnosis in city-level medical institutions. These findings demonstrate that there are overseas imported malaria cases in Dalian City, with falciparum malaria as the predominant type. It is recommended to reinforce the prevention and control of imported malaria, and increase clinicians’ diagnostic capability and residents’ awareness of malaria, in order to sustainably consolidate malaria elimination achievements.

Key words: Malaria, Imported, Epidemiology, Dalian