Malaria in Zhejiang Province, China, from 2005 to 2014

The American Journal of Tropical Medicine and Hygiene, Aug 2015

Hualiang Chen, Linong Yao, Lingling Zhang, Xuan Zhang, Qiaoyi Lu, Kegen Yu, Wei Ruan

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Malaria in Zhejiang Province, China, from 2005 to 2014

Am. J. Trop. Med. Hyg. Hualiang Chen 0 1 Linong Yao 0 1 Lingling Zhang 0 1 Xuan Zhang 0 1 Qiaoyi Lu 0 1 Kegen Yu 0 1 Wei Ruan 0 1 0 for Disease Control and Prevention , Binsheng Road 3399, Hangzhou 310051 , China 1 Zhejiang Provincial Center for Disease Control and Prevention , Hangzhou , China To summarize the changing epidemiological characteristics of malaria in Zhejiang Province, China, we collected data on malaria from the Chinese Notifiable Disease Reporting System (NDRS) and analyzed them. A total of 2,738 malaria cases were identified in Zhejiang Province from 2005 to 2014, of which 2,018 were male and 720 were female. Notably, only 7% of malaria cases were indigenous and the other cases were all imported. The number of malaria cases increased from 2005 to 2007, peaked in 2007, and then decreased from 2007 to 2011. There were no indigenous cases from 2012 to 2014. Of all cases, 68% of cases contracted Plasmodium vivax, 27% of cases contracted P. falciparum, and two cases contracted P. malariae. About 88% of malaria cases during 2005-2011 occurred yearly between May and October, but the number of malaria cases in different months during 2012-2014 was similar. The median age was 33 years, and 1,892 cases occurred in persons aged 20-50 years. The proportion of businessmen increased and the proportion of migrant laborers decreased in recent years. The median time from illness onset to confirmation of malaria cases was 5 days and it decreased from 2005 to 2014. Some epidemiological characteristics of malaria have changed, and businessmen are the emphases to surveillance in every month. - INTRODUCTION Despite widespread elimination and control efforts during the 20th century, malaria continues to be the most important parasitic disease known to humankind. According to the World Health Organization (WHO) estimate in 2014, there were 3.2 billion people at risk of being infected with malaria and developing disease; 198 million cases of malaria and 584,000 deaths occurred globally in 2013.1 Over the span of the last century, almost half of the world’s countries have successfully eliminated malaria.2 Although great success has been achieved since the launch of national malaria control program in 1955, malaria remains a serious public health problem in China.3–5 The Chinese Notifiable Disease Report ing System (NDRS), which was initiated in the 1950s, is the fundamental communicable disease surveillance system in China. After the outbreak of severe acute respiratory syndrome (SARS) in 2003, the Chinese government strengthened the construction of public health information system. On January 1, 2004, the Real-Time Notifiable Infectious Disease Reporting System was put into use nationwide, realizing the timely online monitoring of individual cases, which marks a leap in the surveillance of communicable diseases in China. Zhejiang Province is located in southeastern China, adjacent to Anhui Province, where malaria is endemic. Malaria incidence decreased in recent years in Zhejiang Province, but there were hundreds of imported malaria cases every year and epidemiological characteristics changed.6,7 This stimulated us to analyze the updated epidemiological characteristics of malaria cases in recent years. Case definition. Indigenous malaria was defined as any case infected within the province where it was diagnosed; in contrast, imported malaria was defined as a malaria case whose origin could be traced to an area of transmission outside the province where the diagnosis of malaria was made.8,9 Data collection. Daily disease surveillance data on malaria from 2005 to 2014 were obtained from the NDRS. Information of cases included gender, age, occupation, residential address, type of disease, date of onset, and date of confirmation. Data analysis. Data were analyzed using the Statistical Package for the Social Sciences (SPSS v19; SPSS, Chicago, IL). Categorical variables were summarized by frequencies and numerical variables were summarized by means with standard deviations if normally distributed and medians, interquartile ranges (IQRs), and ranges if not normally distributed. Ethical approval. Experimental research reported in this study has been performed with the approval of the ethics committee of Zhejiang Provincial Center for Disease Control and Prevention (Zhejiang CDC). Human research was carried out in compliance with the Helsinki Declaration. All participants provide their written informed consent to participate in this study. A total of 2,738 malaria cases were identified in Zhejiang Province from 2005 to 2014, of which 2,018 were male and 720 were female. Of note, only 7% (183/2,738) of malaria cases were indigenous and the other cases were all imported. As shown in Figure 1, the number of malaria cases increased from 2005 to 2007 and peaked in 2007, and then the number of malaria cases decreased from 2007 to 2011. Although the number of malaria cases increased from 2012 to 2014, there were no (...truncated)


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Hualiang Chen, Linong Yao, Lingling Zhang, Xuan Zhang, Qiaoyi Lu, Kegen Yu, Wei Ruan. Malaria in Zhejiang Province, China, from 2005 to 2014, The American Journal of Tropical Medicine and Hygiene, 2015, pp. 305-309, 93/2, DOI: 10.4269/ajtmh.15-0080