Abstract:

Objective To analyze the epidemiological characteristics of malaria in Jiangxi Province from 2015 to 2022, to provide scientific basis for formulating prevention and control strategy. Methods Malaria cases and statistical data were collected from the National Infectious Diseases Reporting and Information Management System and the National Information Management System for Parasitic Diseases Control and Prevention, for those cases locally reported and confirmed during January 1st, 2015 to December 31th, 2022 in Jiangxi Province. The collected malaria cases were classified as confirmed cases (microscopic examination and/or PCR test positives confirmed by provincial reference laboratory for malaria diagnosis), clinically diagnosed cases (blood examination positive found by medical institutions, but microscopic examination and PCR test by provincial reference laboratory were negative), and severe case (with complications). Statistical analysis was performed by LSD-t and mann-whitney Test using SPSS 26.0 software. Results From 2015 to 2022, a total of 241 malaria cases were reported in Jiangxi Province, all of which were imported malaria and no deaths were reported. The reported cases in each year were 53, 52, 30, 41, 46, 12, 3, and 4, respectively. Among them, there were 240 confirmed cases and 1 clinically diagnosed case (reported in 2015). Among the confirmed cases, there were 153 cases of falciparum malaria (63.75%), 50 cases of vivax malaria (20.83%), 31 cases of ovale malaria (12.91%), 5 cases of malariae malaria (2.08%), and 1 case of mixed infection of falciparum malaria and vivax malaria (0.41%). The sources of infection are distributed in 34 countries including Africa, Asia, and Oceania, with Africa (a total of 27 countries) accounting for 92.53% (223/241). There are case reports in each month, with a cumulative increase in cases in January, June, and September, and a decrease in cases in October, November, and December. From 2015 to 2019 (before the COVID-19 epidemic) and from 2020 to 2022 (during the COVID-19), the monthly average number of reported cases was 3.7 and 0.53 respectively (t = 6.369, P < 0.05). All 11 prefectures in Jiangxi Province have reported cases, with the top 3 prefectures reporting cases being Nanchang City (51.45%, 124/241), Ganzhou City (15.77%, 38/241), and Yichun City (7.05%, 17/241); The top three counties (cities, districts) reporting cases are Qingshanhu District of Nanchang City (33.19%, 80/241), Donghu District of Nanchang City (9.54%, 23/241), and Zhanggong District of Ganzhou City (7.88%, 19/241). Among the reported cases of malaria, males accounted for 95.44% (230/241) and females accounted for 4.56% (11/241). The age of onset was mainly concentrated between 20 and 50 years old (97.11%, 234/241), mainly reported by medical institutions and disease control centers at or above the county level (99.59%, 240/241). The median interval between onset and initial visit is 1 day; The average number before the COVID-19 was (2.76 ± 5.00) d, and the average number during the epidemic was (1.79 ± 1.81) d, with no statistically significant difference (Z = -0.155, P > 0.05). The median time interval between initial diagnosis and diagnosis is 2 days; The average number before the COVID-19 was (3.36 ± 3.30) d, and the average number during the epidemic was (2.74 ± 2.90) days, with no statistically significant difference (Z = -0.103, P > 0.05). There were 28 severe cases (11.62%) and 213 non severe cases (88.38%). There was no statistically significant difference in the interval between onset and diagnosis (median 6 d) between severe cases and non severe cases (median 4 d) (Z = -1.242, P > 0.05). Conclusion In the malaria post-elimination stage, there remains retransmission risk caused by imported cases, thus it is imperative to continuously strengthen surveillance to prevent from the occurance of severe cases and deaths.

Key words: Malaria, Epidemiological characteristics, Jiangxi