Epidemic features and impact factors on hospitalization of Plasmodium vivax in China 2011-2014

Abstract

To investigate the epidemiological characteristics and impact factors on hospitalization of Plasmodium vivax (P.vivax) since initiation of national malaria elimination program, so as to facilitate the adjustment of technical guideline in response to the epidemic changing of malaria in China. The data of individual P. vivax case (probable and confirmed) and population during 2011-2014 were collated from China National Notifiable Infectious Disease Reporting Information System, and the data of epidemiological investigation for individual P. vivax case (imported and indigenous) during 2011-2014 were collected from China Parasite Disease Prevention and Control Information System. All of the data didn't include China's Hongkong, Macao, Taiwan and foreign cases. The risk factors on hospitalization were explored by multiple factors variable binary classification unconditioned logistic regression model. During study period of four years, a total of 5 656 Plasmodium vivax cases were detected. Among them, 69.9% (3 951 cases) were imported cases and 30.1% (1 705 cases) were autochthonous cases. The male cases accounted for 82.7% of all cases. Among the autochthonous cases, 535 cases (31.4%) occurred in the cross-bordering areas, and 577 cases (33.8%) were reported in the junction of difference provinces. The amount of autochthonous cases decreased from 1 363 cases in 2011 to 53 cases in 2014, and the county affected by autochthonous cases was shrunk from 185 counties to 10 counties. The proportion of autochthonous cases introduced by domestic migrants increased constantly, which reached 41.5% in 2014. The imported cases were detected from 614 counties of 30 provinces, who were originated from 57 overseas countries of 4 continents, with Southeast Asia being the leading origins (2 772 cases, 70.2%). There were 1 494 cases hospitalized for treatment, with the male (OR=1.41, 95%CI: 1.16-1.71), 14 years old and younger (OR=2.26, 95%CI: 1.44-3.56), and oversea imported cases (OR=2.73, 95%CI: 2.30-3.25) were the high risk group for hospitalization. The scale and scope of P. vivax occurrence decreased dramatically since initiation of malaria elimination grogram in 2010. However, the risk of P. vivax introduction by the overseas imported cases and domestic migrants should be highlighted.