Abstract:

Objective To evaluate the epidemiological characteristics of imported malaria and analyze the risk factors for severe malaria in Shanghai, China. Methods A retrospective review was made on imported malaria cases treated in Shanghai Public Health Clinical Center during 2013-2015, focusing on the demographic information, epidemiological data, and laboratory data. Comparisons between groups were made with Mann-Whitney test and Fisher’s exact test, and risk factors were analyzed with multivariate logistic regression. Results Eighty-seven imported malaria cases (82 males and 5 females) were reviewed, with an average onset age of 36.4, comprising 79 Chinese (90.8%), 3 South Sudanese (3.4%), 2 Indians (2.3%), and one from each of Cameroon, Nigeria, and Burundi (1.1%). Seventy-five cases had a defined region of malaria source, with a dominance in African countries (63, 84.0%) and then in Asia (11, 14.7%). Seventy-eight (89.7%) were confirmed by laboratory tests while 9(10.3%) were clinically diagnosed. Among the laboratory confirmed cases, 89.7% were infected with Plasmodium falciparum and 10.3% with P. vivax. Twenty cases(23.0%) had a history of malaria infection. The median of duration from symptom onset to admission was 5 days and 30 (34.5%) patients received anti-malaria drug treatment within 48 hours after onset. Eighteen patients met the diagnostic criteria of severe malaria, of whom 1 showed cerebral malaria, 17 had serum total bilirubin elevating to > 43 μmol/L and 3 had a high serum creatinine level above 265 μmol/L. Multivariate logistic regression showed that medication within 48 h after onset was an independent risk factor for severe malaria (OR = 0.05, 95%CI 0.01-0.43, P < 0.05). Conclusion Plasmodium falciparum remains a major pathogen for imported malaria in Shanghai. Africa is the major region of malaria source. Timely medication after disease onset reduces the risk for sever malaria.

Key words: Imported malaria, Clinical epidemiology, Risk factor, Severe malaria, Plasmodium falciparum