Analysis of the surveillance of the re-transmission risk of imported malaria after elimination in Jinshan District,Shanghai

LI Jing; ZHAO Yiming; WANG Tang; XU Feng; DONG Zhaopeng; ZHU Min

doi:10.19821/j.1671-2781.2025.01.022

Abstract：Objective To analyze the monitoring results of the re-transmission risk of imported malaria after elimination in Jinshan District,Shanghai,China,so as to provide a reference basis for the development of prevention and control strategies.Methods Information on malaria case reports and epidemiologic case questionnaires in Jinshan District,Shanghai,from 2016 to 2023 were collected through National Information System for Infectious Disease surveillance and National Information System for Parasitic Diseases Control and Prevention,while data on surveillance of Plasmodium infection in the population of Jinshan District,Shanghai,and surveillance of malaria-transmitting vectors were collected in 2016-2023,and analyzed using Excel 2010 and SPSS 18.0 software for statistical analysis.The counting data(rates)were compared using the Chi-square test,P＜0.05 indicated a statistically significant difference.Results A total of 67 malaria cases were reported in Jinshan District,Shanghai from 2016 to 2023,with cases reported in all years except 2022,including 62 cases(92.54％)infected with Plasmodium falciparum,4 cases(5.97％)infected with P.ovale,and one case(1.49％)infected with P.vivax.All cases were imported mainly from African countries such as Nigeria(16.42％,11/67),Democratic Republic of Congo(13.43％,9/67)and Cameroon(10.45％,7/67).There was no obvious seasonal distribution of the cases.Reported cases are predominantly male young adults,and mainly returnees who have gone abroad to work.There was only one case with Jinshan district household registration(1.49％),and the rest were from other counties and districts in Shanghai(19.40％,13/67),foreign provinces and cities(73.13％,49/67),and foreigners(5.97％,4/67).All cases were detected by passive surveillance with a positive test rate of 1.71％(162/9 491).The median time from the illness onset to confirmed diagnosis was 4 d,and 47.76％(32/67)of cases were diagnosed within 3 d after the illness onset.The institutions where cases were first seen were mainly provincial medical institutions,accounting for 61.19％(41/67),and 68.66％(46/67)of cases were diagnosed with malaria at the first visit.All cases were disposed of in accordance with Shanghai's"1-2-3+1"work requirements,with a standardized disposal rate of 100％.Vector surveillance in Jinshan District,Shanghai,2016-2023 showed Anopheles sinensis as the only malaria vector in the district.Conclusion After the elimination of malaria,the risk of local re-transmission due to imported malaria epidemics in Jinshan District still exists,and the monitoring and management of imported malaria should continue to be strengthened to consolidate the results of malaria elimination.