Malaria re-emerged in the Huang-Huai Plain of central China during 2006–2008, dominated with Anopheles sinensis as a vector. However, there is no information on strategies based on multi-factor analysis to effectively control the re-emergence of malaria in these areas. Previous experience indicates some relationship between the distribution of water bodies and malaria cases, but more detailed data are not available and in-depth studies have not been conducted up to now. The objective of this study was to identify the relationship between the distribution of water bodies and presentation of malaria cases using spatial analysis tools in order to provide guidance to help formulate effective strategies for use in controlling the sources of malaria infection, based on the identification of risk areas and population.

Background: In areas where malaria has been eliminated, delayed care-seeking and diagnosis of imported malaria are constant threats. This study aimed to describe the profile and determinants of delayed care-seeking and diagnosis among patients with imported malaria in China. Methods: This retrospective study assessed surveillance data obtained from 2014 to 2021 in the Chinese provincial-level administrative divisions (PLADs) of Anhui, Henan, Hubei, and Zhejiang, and Guangxi. Epidemiological characteristics were analyzed using descriptive statistics. Furthermore, factors associated with delayed care-seeking and diagnosis among imported malaria cases were identified using multivariate logistic regression. Results: Overall, 11.81% and 30.08% of imported malaria cases had delays in seeking care and diagnosis, respectively. During the study period, there was a decreasing trend in the proportion of imported malaria cases with delayed care-seeking (χ² = 36.099, P < 0.001) and diagnosis (χ² = 11.395, P = 0.001). In multivariate analysis, independent risk factors associated with delayed care-seeking include PLADs (Guangxi as reference), consultations in high-level facilities for the first medical visit, infections with non-Plasmodium falciparum species, and older age. However, PLADs (Guangxi as reference), the purpose of traveling (labour as reference), and infections with non-P. falciparum species increased the risk of delayed diagnosis. Delayed care-seeking (adjusted odds ratio: 1.79, P = 0.001) and diagnosis (adjusted odds ratio: 1.62, P = 0.004) were risk factors for severe disease development. Conclusions: Based on this study’s findings, we strongly advocate for improved access to quality healthcare to reduce the rate of misdiagnosis at the first visit. Infections caused by non-P. falciparum species should be highlighted, and more sensitive and specific point-of-care detection methods for non-P. falciparum species should be developed and implemented. In addition, education programs should be enhanced to reach target populations at risk of malaria infection. All these factors may reduce delayed care-seeking and diagnosis of imported malaria. Graphical

Background: Although autochthonous malaria cases are no longer reported in Anhui Province, China, imported malaria has become a major health concern. The proportion of reported malaria cases caused by Plasmodium ovale spp. increased to levels higher than expected during 2012 to 2019, and showed two peaks, 19.69% in 2015 and 19.35% in 2018. Methods: A case-based retrospective study was performed using data collected from the China Information System for Disease Control and Prevention (CISDCP) and Information System for Parasitic Disease Control and Prevention (ISPDCP) from 2012 to 2019 to assess the trends and differences between Plasmodium ovale curtisi (P. o. curtisi) and Plasmodium ovale wallikeri (P. o. wallikeri). Epidemiological characteristics were analyzed using descriptive statistics. Results: Plasmodium o. curtisi and P. o. wallikeri were found to simultaneously circulate in 14 African countries. Among 128 patients infected with P. ovale spp., the proportion of co-infection cases was 10.16%. Six cases of co-infection with P. ovale spp. and P. falciparum were noted, each presenting with two clinical attacks (the first attack was due to P. falciparum and the second was due to P. ovale spp.) at different intervals. Accurate identification of the infecting species was achieved among only 20.00% of cases of P. ovale spp. infection. At the reporting units, 32.17% and 6.96% of cases of P. ovale spp. infection were misdiagnosed as P. vivax and P. falciparum infections, respectively. Conclusion: The present results indicate that the potential of P. ovale spp. to co-infect with other Plasmodium species has been previously underestimated, as is the incidence of P. ovale spp. in countries where malaria is endemic. P. o. curtisi may have a long latency period of > 3 years and potentially cause residual foci, thus posing challenges to the elimination of malaria in P. ovale spp.-endemic areas. Considering the low rate of species identification, more sensitive point-of-care detection methods need to be developed for P. ovale spp. and introduced in non-endemic areas.

Background: In 2021, the World Health Organization officially declared the People’s Republic of China as malaria-free. However, despite this milestone achievement, the continued occurrence of severe and fatal cases of imported malaria in China, due to globalization and increased international communication, remains a significant public health concern. Objective: The aim of this study was to elucidate the epidemiological characteristics of imported malaria in 5 Chinese provinces from 2014 to 2021 and to identify the factors that influence complications in imported malaria cases. The findings will provide a basis for enhancing prevention and control measures, thereby consolidating China’s achievements in malaria elimination. Methods: A case-based retrospective study was performed, using surveillance data collected from the representative provinces of China from 2014 to 2021. Epidemiological characteristics were analyzed using descriptive statistics. Logistic regression was used to identify the factors influencing the occurrence of complications. Results: A total of 5559 malaria cases were included during the study period. The predominant species was Plasmodium falciparum (3940/5559, 70.9%), followed by Plasmodium ovale (1054/5559, 19%), Plasmodium vivax (407/5559, 7.3%), Plasmodium malariae (157/5559, 2.8%), and 1 case of Plasmodium knowlesi. Most of the cases were male (5343/5559, 96.1%). The complication rates for P falciparum and P ovale were 11.4% and 3.3%, respectively. Multivariate logistic regression analysis of the relevant factors of malaria complications revealed potential protective factors, including a previous infection by Plasmodium (P<.001; odds ratio [OR] 0.512, 95% CI 0.422‐0.621), and risk factors, including increased age (P=.004; OR 1.014, 95% CI 1.004‐1.024), misdiagnosis at the first clinical visit (P<.001; OR 3.553, 95% CI 2.886‐4.375), and the time interval from onset to treatment (P=.001; OR 1.026, 95% CI 1.011‐1.042). Subgroup analyses identified risk factors associated with P falciparum, which include advanced age (P=.004; OR 1.015, 95% CI 1.005‐1.026), initial misdiagnosis during the first clinical visit (P<.001; OR 3.549, 95% CI 2.827‐4.455), the time interval from onset to treatment (P<.001; OR 1.043, 95% CI 1.022‐1.063), and a delay of more than 3 days from the first treatment to diagnosis (P<.001; OR 2.403, 95% CI 1.823‐3.164). Additionally, the risk factors pertaining to P ovale involve misdiagnosis at the initial clinical visit (P=.01; OR 2.901, 95% CI 1.336‐6.298), the time interval from onset to treatment (P=.002; OR 1.095, 95% CI 1.033‐1.160), and the duration from the initial treatment to diagnosis (P=.43; OR 1.032, 95% CI 0.953‐1.118). Previous infections can prevent the progression of both P falciparum and P ovale. Conclusions: This study showed that the increasing proportion of P ovale in recent years should not be ignored. Furthermore, there is a need to improve diagnostic awareness, enhance the capacity of medical institutions, and provide health education for high-risk groups.