Epidemiological characteristics of imported malaria in Shenzhen City

Objective To analyze the epidemiological characteristics of imported malaria in Shenzhen so as to provide the scientific basis for developing control strategies.Methods A retrospective study was conducted with the data on surveillance and incidence of imported malaria in Shenzhen during 2009-2013.The imported malaria cases were analyzed using descriptive epidemiological methods to indicate their distribution characteristics among different population groups,regions,and seasons.Results The number of imported malaria cases were 128 from 2009 to 2013,of which 77 cases (60.2％) infected with Plasmodiumfolciparum,44 cases(34.3％) with Plasmodium vivax,and 7 case(5.5％) with Plasmodium spp.not identified.Annual incidence of imported malaria and its proportion to total malaria cases were increasing in recent five years.Among the imported malaria cases,90 cases (70.3％) were imported from Africa,25 cases (19.5％) from Southeast Asia,12 cases(9.4％) from other provinces of China,and 1 case(0.8％) from South America.Imported malaria cases were reported in every district around Shenzhen areas,ranking from top to lowest,42,37,24,18,6 and 1 cases reported in Longgang,Nanshan,Baoan,Futian,Luohu and Yantian district respectively.The cases were occurred from January to December,and no seasonal incidence peak was observed during 2009-2013.The majority of malaria cases was male,the ratio of male to female was 7.5 ∶ 1,and about 88.3％(113/128) of the total cases were concentrated in 20～50 age groups.The exported labor workers and travelers for business from malaria endemic areas,such as Africa and South-east Asia,were of high risk to malaria.Totally 115 (89.8％) cases were laboratory confirmed while 13 (10.2％) clinically diagnosed,and the medium time from malaria onset to diagnosed by doctors was 5 d.About 95.3％ (122/128) patients received complete treatment with anti-malaria drugs in hospitals,however one patient died of P.falciparum malaria because of delayed diagnosis.Conclusion The management of imported malaria is very important in the elimination of malaria in Shenzhen.Imported malaria surveillance and health intervention should be conducted among travelers to malaria endemic area,meanwhile clinical medical staffs should receive more professional training to improve diagnosis and treatment of malaria cases. Key words: Malaria;  Epidemiological study;  Shenzhen