Imported Malaria in China, 2012

To the Editor: Imported malaria has become a major public health challenge in China. Despite an 89.8% decrease in total cases from 2008 (26,873) through 2012 (2,729), the proportion of imported malaria cases has increased from 14.7% to 89.0% (1). We analyzed the malaria situation in China in 2012 by using data obtained from the national information reporting system of infectious diseases. In this analysis, an imported case of malaria was defined as case of malaria acquired in a known malarious area outside China. In China, the following criteria for imported malaria must be simultaneously met: 1) the patient was given a diagnosis of malaria; 2) the patient had a travel history to malaria-endemic areas outside China during malaria transmission season; and 3) the onset time for malaria for the person was <1 month after returning to China during the local transmission season. This definition of malaria was based on the latent period for all Plas-modium species reported in China. Of 2,729 malaria cases reported in 2012, a total of 2,428 (89.0%) were imported. Fifteen of these cases were in persons who died of infection with P. falciparum. In the imported cases, 4 Plasmodium species were identified: [0.8%]), and mixed infections (n = 21 [0.9%]). Among imported cases, 13 (0.5%) were clinically diagnosed. Chinese workers who returned from Africa (n = 1,458 [60.0%]) had most cases imported malaria. A total of 37 countries in Africa were sources of imported cases. Most cases were was another major source of imported cases. These case-patients were infected mostly with P. vivax (n = 658 [73.5%]) (Table). Imported cases increased during April, reached a peak during May (n = 297 [12.2%]), and decreased during July. This trend was caused by workers returning to China to perform agricultural work during this period. The male:female patient ratio was 14.6:1 (n = 2,272 male patients:156 female patients); most (n = 2,240 [95.2%]) mobile laborers are men. The mean age of persons with imported cases was 40.8 years. Most (n = 1,813 [74.7%]) of these persons were 15–44 years of age and few (n = 5 [0.2%]) were <5 years of age. Persons with imported cases were detected in 29 provinces (Hong Kong, Macao, and Taiwan did not join the information system). Provinces had the largest number of imported cases. Our analysis indicated that imported malaria poses major challenges to the malaria elimination program in China. One challenge …