Changing malaria transmission and implications in China towards National Malaria Elimination Programme between 2010 and 2012

Malaria epidemiological characteristics and control in Guangzhou, China, 1950-2022

BACKGROUND

Malaria was once widespread in Guangzhou, China. However, a series of control measures have succeeded in eliminating local malaria infections. Based on the analysis of the characteristics of malaria epidemics in Guangzhou, China, from 1950 to 2022, the changes and effectiveness of malaria control strategies and surveillance management in Guangzhou from 1950 to 2022 are described.

METHODS

Data on malaria prevention and treatment in Guangzhou from 1950 to 2022 were collected, and descriptive epidemiological methods were used to analyse the prevalence of malaria, preventive and control measures taken, and the effectiveness of prevention and treatment in different periods. Data on malaria cases were obtained from the Guangzhou Centre for Disease Control and Prevention (CDC) and the China Communicable Disease Reporting System.

RESULTS

The development of the malaria control system in Guangzhou has gone through four periods: 1. High malaria prevalence (1950-1979), 2. Intensive prevention and control stage (1980-2000), 3. Consolidating gains in malaria control (2001-2008), and 4. Preventing reestablishment of transmission (2009-2022). During Period 1, only medical institutions at all levels and the local CDCs, the Guangzhou CDC participated in the malaria prevention and control system, establishing a three-tier health system on malaria prevention and control. During Period 2, other types of organizations, including the agricultural sector, schools and village committees, the construction department and street committee, are involved in the malaria control system. During Period 3, more and more organizations are joining forces to prevent and control malaria. A well-established multisectoral malaria control mechanism and an improved post-elimination surveillance management system are in place. Between 1950 and 2022, a total of 420,670 cases of malaria were reported. During Period 1, there was an epidemic of malaria in the early 1950s, with an annual incidence rate of more than 10,000/100,000, including a high rate of 2887.98/100,000 in 1954. In Period 2 malaria was gradually brought under control, with the average annual malaria incidence rate dropping to 3.14/100,000. During Period 3, the incidence rate was kept below 1/100,000, and by 2009 local malaria infections were eliminated.

CONCLUSION

For decades, Guangzhou has adopted different malaria control strategies and measures at different epidemic stages. Increased collaboration among civil organizations in Guangzhou in malaria control has led to a significant decline in the number of malaria cases and the elimination of indigenous malaria infections by 2009.The experience of Guangzhou can guide the development of malaria control strategies in other cities experiencing similar malaria epidemics.

1-3-7 surveillance and response approach in malaria elimination: China's practice and global adaptions

There has been a significant reduction in malaria morbidity and mortality worldwide from 2000 to 2019. However, the incidence and mortality increased again in 2020 due to the disruption to services during the COVID-19 pandemic. Surveillance to reduce the burden of malaria, eliminate the disease and prevent its retransmission is, therefore, crucial. The 1-3-7 approach proposed by China has played an important role in eliminating malaria, which has been internationally popularized and adopted in some countries to help eliminate malaria. This review summarizes the experience and lessons of 1-3-7 approach in China and its application in other malaria-endemic countries, so as to provide references for its role in eliminating malaria and preventing retransmission. This approach needs to be tailored and adapted according to the region condition, considering the completion, timeliness and limitation of case-based reactive surveillance and response. It is very important to popularize malaria knowledge, train staff, improve the capacity of health centres and monitor high-risk groups to improve the performance in eliminating settings. After all, remaining vigilance in detecting malaria cases and optimizing surveillance and response systems are critical to achieving and sustaining malaria elimination.

Evolution of anti-malaria policies and measures in P.R. China for achieving and sustaining malaria-free

Malaria is a major public health threat worldwide, and it was also widely prevalent in the history in China, seriously endangering people's health and affecting socioeconomic development. China was certified malaria elimination in 2021 with unremitting efforts since the founding of the People's Republic of China in 1949. This great achievement has been another milestone in the fight against major infectious diseases following the elimination of smallpox, poliomyelitis, leprosy, filariasis, neonatal tetanus and blinding trachoma in China. This paper briefly introduces the malaria burden dynamics and the corresponding malaria transmission risk stratificantions, as well as systematically reviews the evolution of anti-malaria policies and measures from severe epidemic to elimination in China. Meanwhile, five key lessons in malaria control and elimination in China are also briefly summarized. All of the above provide evidences for promoting global malaria eradication and preventing reestablishment of malaria transmission, finally benefit all individuals still suffering from the scourge of malaria.

Genetic diversity of Plasmodium vivax populations from the China-Myanmar border identified by genotyping merozoite surface protein markers

BACKGROUND

Parasite diversity and population structure influence malaria control measures. Malaria transmission at international borders affects indigenous residents and migrants, defying management efforts and resulting in malaria re-introduction. Here we aimed to determine the extent and distribution of genetic variations in Plasmodium vivax populations and the complexity of infections along the China-Myanmar border.

METHODS

We collected clinical P. vivax samples from local and migrant malaria patients from Laiza and Myitsone, Kachin State, Myanmar, respectively. We characterized the polymorphisms in two P. vivax merozoite surface protein markers, Pvmsp-3α and Pvmsp-3β, by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. We sought to determine whether these genetic markers could differentiate these two neighboring parasite populations.

RESULTS

PCR revealed three major size variants for Pvmsp-3α and four for Pvmsp-3β among the 370 and 378 samples, respectively. PCR-RFLP resolved 26 fragment-size alleles by digesting Pvmsp-3α with Alu I and Hha I and 28 alleles by digesting Pvmsp-3β with Pst I. PCR-RFLP analysis of Pvmsp-3α found that infections in migrant laborers from Myitsone bore more alleles than did infections in residents of Laiza, while such difference was not evident from genotyping Pvmsp-3β. Infections originating from these two places contained distinct but overlapping subpopulations of P. vivax. Infections from Myitsone had a higher multiplicity of infection as judged by the size of the Pvmsp-3α amplicons and alleles after Alu I/Hha I digestion.

CONCLUSIONS

Migrant laborers from Myitsone and indigenous residents from Laiza harbored overlapping but genetically distinct P. vivax parasite populations. The results suggested a more diverse P. vivax population in Myitsone than in the border town of Laiza. PCR-RFLP of Pvmsp-3α offers a convenient method to determine the complexity of P. vivax infections and differentiate parasite populations.

What India can learn from globally successful malaria elimination programmes

India is targeting malaria elimination by 2030. Understanding and adopting the strategies employed by countries that have successfully eliminated malaria can serve as a crucial thrust in this direction for a geographically diverse country like India. This analysis is based on extensive literature search on malaria elimination policies, strategies and programmes adopted by nine countries (China, El Salvador, Algeria, Argentina, Uzbekistan, Paraguay, Sri Lanka, Maldives and Armenia) which have attained malaria-free status over the past decade. The key points which India can learn from their journey are mandatory time-bound response in the form of case reporting and management, rapid vector control response, continuous epidemiological and entomological surveillance, elevated community participation, more training and capacity building, private sector involvement, use of quality diagnostics, cross-border collaborations, inclusion of prevention of re-establishment programmes into the elimination plans, higher investment in research, and uninterrupted funds for successful implementation of malaria elimination programmes. These learnings would help India and other South Asian countries steer their programmes by devising tailor-made strategies for their own regions.

Vector control in China, from malaria endemic to elimination and challenges ahead

BACKGROUND

Vector control is an important approach to preventing and controlling malaria. From the malaria epidemic to malaria elimination in China, vector control has played an essential and irreplaceable role in the historical process. This review systematically summarizes the evolution, adjustment, and optimization of vector control strategy towards elimination and discusses the challenges ahead.

MAIN TEXT

This review first summarizes the evolution of vector control strategies during different stages of malaria epidemic, control, elimination, and post-elimination in China. We then distill the vector control experience and lessons in different stages. We discuss the current and future challenges and propose future research directions and developments for novel malaria vector control strategies.

RESULTS

Vector control has played an invaluable role in achieving malaria elimination. China adopted different prevention and control measures in response to the different malaria-endemic situations and vector distributions. Firstly, baseline surveys were initiated to establish the entomological data and helped clarify the prevention priorities and targets. Secondly, targeted and adjusted vector control strategies were conducted in various regions according to the local epidemic characteristics and different vector species. Thirdly, scientific research facilitated efficient vector-control strategies. In addition, the overall economic and social development have promoted environmental improvement, personal protection, and health care. Prediction of the vector distribution was integrated into risk assessment strategies, allowing for sustaining achievements in risk areas.

CONCLUSIONS

The tailored and adapted vector control strategies have played a critical role in China's malaria prevention, control, and elimination. Achievements and lessons learned on vector control from this progress would provide a practical reference in coping with the challenges and potential barriers other countries face in the global effort to eliminate malaria.

Key takeaways from China's success in eliminating malaria: leveraging existing evidence for a malaria-free world

Although the total number of malaria cases and fatalities have declined globally since 2010, there were still 241 million malaria cases identified across 85 countries and territories in 2020. As the global malaria eradication process accelerates, more countries have launched their own initiatives of elimination. Notably, China achieved this goal by 2021, ending thousands of years of endemic. Undoubtedly, tremendous experience and vital lessons have been accrued en route to the malaria-free goal in malaria-eliminated countries including China. To enhance prospects of a malaria-free world by bridging the key evidence from a malaria-eliminated country to the contexts of affected, this personal view highlights concerted commitments and universal investment in healthcare, improved surveillance and response system, constant capacity building, demand-oriented scientific research, and multiway cooperation, which have helped China to eliminate this ancient scourge. We discuss how these key takeaways could be leveraged to different contexts. We also argue the long-term challenges and barriers on the pathway to malaria elimination and underline the needs for consistent efforts to maintain zero indigenous cases and prevent re-introduction of malaria. Through concerted efforts from global collaboration, a malaria-free world can become a reality.

Predicting the impact of climate change on the re-emergence of malaria cases in China using LSTMSeq2Seq deep learning model: a modelling and prediction analysis study

OBJECTIVES

Malaria is a vector-borne disease that remains a serious public health problem due to its climatic sensitivity. Accurate prediction of malaria re-emergence is very important in taking corresponding effective measures. This study aims to investigate the impact of climatic factors on the re-emergence of malaria in mainland China.

DESIGN

A modelling study.

SETTING AND PARTICIPANTS

Monthly malaria cases for four Plasmodium species (P. falciparum, P. malariae, P. vivax and other Plasmodium) and monthly climate data were collected for 31 provinces; malaria cases from 2004 to 2016 were obtained from the Chinese centre for disease control and prevention and climate parameters from China meteorological data service centre. We conducted analyses at the aggregate level, and there was no involvement of confidential information.

PRIMARY AND SECONDARY OUTCOME MEASURES

The long short-term memory sequence-to-sequence (LSTMSeq2Seq) deep neural network model was used to predict the re-emergence of malaria cases from 2004 to 2016, based on the influence of climatic factors. We trained and tested the extreme gradient boosting (XGBoost), gated recurrent unit, LSTM, LSTMSeq2Seq models using monthly malaria cases and corresponding meteorological data in 31 provinces of China. Then we compared the predictive performance of models using root mean squared error (RMSE) and mean absolute error evaluation measures.

RESULTS

The proposed LSTMSeq2Seq model reduced the mean RMSE of the predictions by 19.05% to 33.93%, 18.4% to 33.59%, 17.6% to 26.67% and 13.28% to 21.34%, for P. falciparum, P. vivax, P. malariae, and other plasmodia, respectively, as compared with other candidate models. The LSTMSeq2Seq model achieved an average prediction accuracy of 87.3%.

CONCLUSIONS

The LSTMSeq2Seq model significantly improved the prediction of malaria re-emergence based on the influence of climatic factors. Therefore, the LSTMSeq2Seq model can be effectively applied in the malaria re-emergence prediction.

Four decades of epidemiological data reveal trajectories towards malaria elimination in Kheda district (Gujarat), western part of India

BACKGROUND

Malaria is a main public health problem in India and was so particularly in the state of Gujarat in the western part of the country. This study assesses the effects of various interventions on malaria cases using data from the last 33 years (1987-2019).

METHODS

Here we have analysed 33 years of malaria epidemiological data from a malaria clinic in Kheda district in Gujarat. The data were digitised yearly and monthly, age-wise and gender-wise, and descriptive analysis was performed to assess the effects of several interventions on malaria burden.

RESULTS

During 1987-2019, our clinic diagnosed 5466 Plasmodium vivax and 4732 P. falciparum malaria cases. Overall, there was a declining trend in malaria cases except for the years 1991, 1994, 2004 and 2005. The year 2004 especially witnessed an epidemic in Kheda as well as throughout Gujarat. Malaria infections were most common (40%) among the 21-40 years age group. Fever was the most common symptom in all age groups.

INTERPRETATION

Introduction of revised drug policy and improved surveillance technique (rapid diagnosis kits) have strengthened the diagnosis and treatment of malaria in the district. Use of pyrethroid in indoor residual insecticide spray has also strengthened vector control. Among the various interventions used, long-lasting insecticide nets and introduction of artemisinin-based combination therapy have played significant roles in controlling malaria cases. A more drastic decline in P. falciparum cases versus P. vivax is evident, but the latter persists in high proportions and therefore new tools for malaria control will be needed for elimination.

Surveillance of Malaria Vectors - 18 Sites, 12 PLADs, China, 2018-2020

What is already known on this topic?

Malaria is an infectious parasitic disease transmitted by the bite of Anopheles mosquitoes and is a serious threat to human health. Surveillance of malaria vectors is part of the integrated strategy for malaria elimination in China.

What is added by this report?

This research supplements the population distribution, density, and seasonal fluctuation of malaria vectors in the Anopheles surveillance sites from 2018 to 2020 in China.

What are the implications for public health practice?

Continuous surveillance of malaria vectors is important for maintaining malaria-free status in China and for providing a scientific basis for risk assessment of malaria retransmission.

Contribution of NIPD-CTDR to the parasitic diseases control and elimination in China: Memory of the 70th anniversary for NIPD-CTDR

China has achieved a great success in control and elimination of key parasitic diseases. In 2007, the elimination of lymphatic filariasis was verified by WHO. The schistosomiasis incidence and snail-distributed areas have reduced to the lowest level in the history. The transmission and disease burden of echinococcosis have been contained largely, and the populations infected with soil-transmitted trematode and food-borne parasites have also shown a significantly declining trend. Because of rapid globalization and climate changes, however, many new challenges have arisen. In his paper, the 2020-2030 roadmaps towards the control and elimination of these key parasitic diseases are described. Moreover, China is actively implementing its global health strategy, and will be more and more engaged into global health affairs, in which a series of China-Africa health cooperation projects have been in planning with a wish of making a greater contribution to the SDGs.

Epidemiological big data and analytical tools applied in the control programmes on parasitic diseases in China: NIPD's sustained contributions in 70 years

The analysis of epidemiological data has played an important role for the academic research carried out by the National Institute of Parasitic Diseases, China CDC, since its foundation in 1950s. Those researches, e.g., the temporal-spatial patterns of disease transmission and the identification of risk factors, have contributed significantly to the national parasitic disease control and elimination programmes in China. With the development and application of epidemiological data analysis in the last decade, all research results improve our understanding of parasitic diseases epidemiology and related health issues through the application platform of epidemiological big data and analytical tools. In particular, implementation research on analytical predictions on disease outbreak or epidemic risks have provided references to the scientific guidance on effective preventions and interventions in the parasitic disease elimination in China, such as fliariasis, malaria and schistosomiasis. This review has reflected the function of data accumulation and application of temporospatial tools in parasitic diseases control, and the ways of the NIPD's sustained contributions to the disease control programmes in China.

From inspiration to translation: Closing the gap between research and control of helminth zoonoses in Southeast Asia

Poverty magnifies limitations resulting from traditional biases and environmental risks in endemic areas. Any approach towards disease control needs to recognise that socially embedded vulnerabilities can be as powerful as externally imposed infections. Important for RNAS was networking across borders, not just on schistosomiasis but on the whole spectrum of endemic helminthiases, and this bore fruit in the form of the expansion of RNAS into the 'Regional Network on Asian Schistosomiasis and other Helminth Zoonoses (RNAS⁺)', which focuses on technical standardization, supporting the growth of research capacity and the further development of networking. Administration is lean and largely virtual with the focus on connecting members via the Internet, providing databases and administrative back-up. The strategy emphasizes ways and means to alleviate the spectre of disease and poverty from the endemic areas through boosting research on target diseases and supporting collaboration between basic and operational research on the one hand and control/elimination activities on the other. RNAS⁺ also benefits from continuing input from outside research institutions in areas outside Southeast Asia. This paper is aiming to identify the priority actions to close the gap between researcher and policy makers.

Imported malaria cases in former endemic and non-malaria endemic areas in China: are there differences in case profile and time to response?

BACKGROUND

China has achieved zero indigenous malaria case report in 2017. However, along with the increasing of international cooperation development, there is an increasing number of imported malaria cases from Chinese nationals returning from malaria-affected countries. Previous studies have focused on malaria endemic areas in China. There is thus limited information on non-endemic areas in China, especially on the performance of malaria surveillance and response in health facilities.

METHODS

A comparative retrospective study was carried out based on routine malaria surveillance data collected from 2013 to 2017. All imported malaria cases reported within the mainland of China were included. Variables used in the comparative analysis between cases in former endemic and former non-endemic areas, included age, gender and occupation, destination of overseas travel, Plasmodium species and patient health outcome. Monthly aggregated data was used to compare seasonal and spatial characteristics. Geographical distribution and spatial-temporal aggregation analyses were conducted. Time to diagnosis and report, method of diagnosis, and level of reporting/diagnosing health facilities were used to assess performance of health facilities.

RESULTS

A total of 16 733 malaria cases, out of which 90 were fatal, were recorded in 31 provinces. The majority of cases (96.2%) were reported from former malaria endemic areas while 3.8% were reported from former non-malaria endemic areas. Patients in the age class from 19 to 59 years and males made the highest proportion of cases in both areas. There were significant differences between occupational categories in the two areas (P <  0.001). In former endemic areas, the largest proportion of cases was among outdoor workers (80%). Two peaks (June, January) and three peaks (June, September and January) were found in former endemic and former non-endemic areas, respectively. Time between the onset of symptoms and diagnosis at clinics was significantly different between the two areas at different level of health facilities (P <  0.05).

CONCLUSIONS

All the former non-endemic areas are now reporting imported malaria cases. However, the largest proportion of imported cases is still reported from former endemic areas. Health facilities in former endemic areas outperformed those in former non-endemic areas. Information, treatment, and surveillance must be provided for expatriates while capacity building and continuous training must be implemented at health facilities in China.

Application of community-based and integrated strategy to reduce malaria disease burden in southern Tanzania: the study protocol of China-UK-Tanzania pilot project on malaria control

Background

During the past six decades, remarkable success on malaria control has been made in China. The major experience could be shared with other malaria endemic countries including Tanzania with high malaria burden. Especially, China’s 1–3-7 model for malaria elimination is one of the most important refined experiences from many years’ efforts and key innovation measures for malaria elimination in China.

Methods

The China-UK-Tanzania pilot project on malaria control was implemented from April, 2015 to June, 2018, which was an operational research with two communities receiving the proposed interventions and two comparable communities serving as control sites. The World Health Organization “Test, Treat, Track” (WHO-T3) Initiative, which calls for every suspected case to receive a diagnostic test, every confirmed case to be treated, and for the disease to be tracked, was integrated with Chinese experiences on malaria control and elimination for exploration of a proper model tailored to the local settings. Application of China’s 1–3-7 model integrating with WHO-T3 initiative and local resources aiming at reducing the burden of malaria in terms of morbidity and mortality by 30% in the intervention communities in comparison with that at the baseline survey.

Discussion

The China-UK-Tanzania pilot project on malaria control was that at China's first pilot project on malaria control in Africa, exploring the feasibility of Chinese experiences by China-Africa collaboration, which is expected that the strategies and approaches used in this project could be potential for scaling up in Tanzania and African countries, and contribute to the acceleration of malaria control and elimination in Africa.

Electronic supplementary material

The online version of this article (10.1186/s40249-018-0507-3) contains supplementary material, which is available to authorized users.

Competency and challenges in malaria microscopy in China

Precise diagnosis is a key measure for malaria control and elimination, and malaria microscopy is still the gold standard method recommended by the World Health Organization (WHO) for malaria diagnosis. Analysis of the competency in malaria microscopy in China will benefit to identify the challenges in this skill and provide some suggestions for improvement in order to reach the requirement of WHO procedures for certification of malaria elimination, and finally contribute to malaria elimination by 2020 in China. According to a series of external assessment activities about malaria microscopy, malaria microscopists from both the national and provincial level but not the levels below provincial level performed quite well in Plasmodium spp identification, but their competency in differentiation of P. ovale and P. vivax and parasite counting by microscopy were not good enough at all levels. Therefore, it is necessary to strengthen the competency in species identification and parasite counting especially at the lower levels in the first line through training and practice as well as regular quality assurance with enough policy support.

Projecting potential spatial and temporal changes in the distribution of Plasmodium vivax and Plasmodium falciparum malaria in China with climate change

BACKGROUND

Global climate change is likely to increase the geographic range and seasonality of malaria transmission. Areas suitable for distribution of malaria vectors are predicted to increase with climate change but evidence is limited on future distribution of malaria with climate in China.

OBJECTIVE

Our aim was to assess a potential effect of climate change on Plasmodium vivax (P. vivax) and Plasmodium falciparum (P. falciparum) malaria under climate change scenarios.

METHODS

National malaria surveillance data during 2005-2014 were integrated with corresponding climate data to model current weather-malaria relationship. We used the Generalized Additive Model (GAM) with a spatial component, assuming a quasi-Poisson distribution and including an offset for the population while accounting for potential non-linearity and long-term trend. The association was applied to future climate to project county-level malaria distribution using ensembles of Global Climate Models under two climate scenarios - Representative Concentration Pathways (RCP4.5 and RCP8.5).

RESULTS

Climate change could substantially increase P. vivax and P. falciparum malaria, under both climate scenarios, but by larger amount under RCP8.5, compared to the baseline. P. falciparum is projected to increase more than P. vivax. The distributions of P. vivax and P. falciparum malaria are expected to increase in most regions regardless of the climate scenarios. A high percentage (>50%) increases are projected in some counties of the northwest, north, northeast, including northern tip of the northeast China, with a clearer spatial change for P. vivax than P. falciparum under both scenarios, highlighting potential changes in the latitudinal extent of the malaria.

CONCLUSION

Our findings suggest that spatial and temporal distribution of P. vivax and P. falciparum malaria in China will change due to future climate change, if there is no policy to mitigate it. These findings are important to guide the malaria elimination goal for China.

Projecting environmental suitable areas for malaria transmission in China under climate change scenarios

INTRODUCTION

The proportion of imported malaria cases in China has increased over recent years, and has presented challenges for the malaria elimination program in China. However, little is known about the geographic distribution and environmental suitability for malaria transmission under projected climate change scenarios.

METHODS

Using the MaxEnt model based on malaria presence-only records, we produced environmental suitability maps and examined the relative contribution of topographic, demographic, and environmental risk factors for P. vivax and P. falciparum malaria in China.

RESULTS

The MaxEnt model estimated that environmental suitability areas (ESAs) for malaria cover the central, south, southwest, east and northern regions, with a slightly wider range of ESAs extending to the northeast region for P. falciparum. There was spatial agreement between the location of imported cases and area environmentally suitable for malaria transmission. The ESAs of P. vivax and P. falciparum are projected to increase in some parts of southwest, south, central, north and northeast regions in the 2030s, 2050s, and 2080s, by a greater amount for P. falciparum under the RCP8.5 scenario. Temperature and NDVI values were the most influential in defining the ESAs for P. vivax, and temperature and precipitation the most influential for P. falciparum malaria.

CONCLUSION

This study estimated that the ESA for malaria transmission in China will increase with climate change and highlights the potential establishment of further local transmission. This model should be used to support malaria control by targeting areas where interventions on malaria transmission need to be enhanced.

The Epidemiology of Imported Acute Infectious Diseases in Zhejiang Province, China, 2011-2016: Analysis of Surveillance Data

To explore epidemiological characteristics of imported acute infectious diseases between 2011 and 2016 in Zhejiang province, China. Data of imported infectious diseases from 2011 to 2016 was collected from the China Information System for Disease Control and Prevention in Zhejiang province, and subsequently analyzed for epidemiological characteristics. A survey was conducted to investigate clinicians' abilities to diagnose these diseases in Zhejiang province. From 2011 to 2016, 1,241 cases of imported acute infectious disease were reported in Zhejiang province, including 1,078 malaria cases, 156 dengue cases, three chikungunya fever cases and four Zika cases. Between 2011 and 2016, incidences of these diseases increased (P < 0.001). For malaria, male adults for labor export were the most affected group. Seasonal fluctuation was not obvious. Plasmodium falciparum was the main malaria type (822 cases) and most cases were acquired from African Region (791/822, 96.1%). Plasmodium vivax cases (194 cases) were mainly from African Region (78/194, 40.2%) and South-East Asia Region (51/194, 26.3%). Meanwhile, for dengue, adults and tourists were the most affected groups. The incidence of dengue was particularly high in August and October. The percent of correct clinician responses in the survey of diagnosis knowledge was 54.6% (standard deviation = 21.0%); this percentage was particularly low in general practitioners and clinicians from township hospitals. The capabilities of clinicians to diagnose these diseases were low and should be improved. Efforts should be made in improving and disseminating proper preventive measures of high-risk populations, surveillance of imported cases, and prevention and control of local epidemics.

PopNet: A Markov Clustering Approach to Study Population Genetic Structure

With the advent of low cost, high-throughput genome sequencing technology, population genomic data sets are being generated for hundreds of species of pathogenic, industrial, and agricultural importance. The challenge is how best to analyze and visually display these complex data sets to yield intuitive representations capable of capturing complex evolutionary relationships. Here we present PopNet, a novel computational method that identifies regions of shared ancestry in the chromosomes of related strains through clustering patterns of genetic variation. These relationships are subsequently visualized within a network by a novel implementation of chromosome painting. We apply PopNet to three diverse populations that feature differential rates of recombination and demonstrate its ability to capture evolutionary relationships as well as associate traits to specific loci. Compared with existing tools, PopNet provides substantial advances by both removing the need to predefine a single reference genome that can bias interpretation of population structure, as well as its ability to visualize multiple evolutionary relationships, such as recombination events and shared ancestry, across hundreds of strains.

Adapting the local response for malaria elimination through evaluation of the 1-3-7 system performance in the China-Myanmar border region

Background

Assessing the essential components of ‘1-3-7’ strategy along the China–Myanmar border is critical to identify gaps and challenges to support evidence-based decision making.

Methods

A mixed-method retrospective study including quantitative and qualitative analysis of the 1-3-7 system components was conducted. Sampled counties were chosen based on malaria incidence from 1 January 2012 to 31 December 2014.

Results

All 260 confirmed malaria cases from sampled counties were reported within 1 day and had completed case investigations. 70.0% of all Reactive Case Detection (RACD) events were conducted and 90.1% of those were within 7 days. Only ten additional individuals were found malaria positive out of 3662 individuals tested (0.3%) by rapid diagnostic test during RACD events.

Conclusions

Key gaps were identified in case investigation and RACD activities in Yunnan Province border counties. This evidence supports improving the RACD (or “7”) response strategy in this setting. Given the challenges in this border region, it will be critical to adapt the RACD response to promote the malaria elimination along the China border.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1707-1) contains supplementary material, which is available to authorized users.

Malaria control and prevention towards elimination: data from an eleven-year surveillance in Shandong Province, China

BACKGROUND

Shandong Province experienced a declining malaria trend of local-acquired transmission, but the increasing imported malaria remains a challenge. Therefore, understanding the epidemiological characteristics of malaria and the control and elimination strategy and interventions is needed for better planning to achieve the overall elimination goal in Shandong Province.

METHODS

A retrospective study was conducted and all individual cases from a web-based reporting system were reviewed and analysed to explore malaria-endemic characteristics in Shandong from 2005 to 2015. Annual malaria incidence reported in 2005-2015 were geo-coded and matched to the county-level. Spatial cluster analysis was performed to evaluate any identified spatial disease clusters for statistical significance. The space-time cluster was detected with high rates through the retrospective space-time analysis scanning using the discrete Poisson model.

RESULTS

The overall malaria incidence decreased to a low level during 2005-2015. In total, 1564 confirmed malaria cases were reported, 27.1% of which (n = 424) were indigenous cases. Most of the indigenous case (n = 339, 80.0%) occurred from June to October. However, the number and scale of imported cases have been increased but no significant difference was observed during months. Shandong is endemic for both Plasmodium vivax (n = 730) and Plasmodium falciparum (n = 674). The disease is mainly distributed in Southern (n = 710) and Eastern region (n = 424) of Shandong, such as Jinning (n = 214 [13.7%]), Weihai (n = 151 [9.7%]), and Yantai (n = 107 [6.8%]). Furthermore, the spatial cluster analysis of malaria cases from 2005 to 2015 indicated that the diseased was not randomly distributed. For indigenous cases, a total of 15 and 2 high-risk counties were determined from 2005 to 2009 (control phase) and from 2010 to 2015 (elimination phase), respectively. For imported cases, a total of 26 and 29 high-risk counties were determined from 2005 to 2009 (control phase) and from 2010 to 2015 (elimination phase), respectively. The method of spatial scan statistics identified different 13 significant spatial clusters between 2005 and 2015. The space-time clustering analysis determined that the most likely cluster included 14 and 19 counties for indigenous and imported, respectively.

CONCLUSIONS

In order to cope with the requirements of malaria elimination phase, the surveillance system should be strengthened particularity on the frequent migration regions as well as the effective multisectoral cooperation and coordination mechanisms. Specific response packages should be tailored among different types of cities and capacity building should also be improved mainly focus on the emergence response and case management. Fund guarantees for scientific research should be maintained both during the elimination and post-elimination phase to consolidate the achievements of malaria elimination.

Surveillance and response for high-risk populations: what can malaria elimination programmes learn from the experience of HIV?

To eliminate malaria, malaria programmes need to develop new strategies for surveillance and response appropriate for the changing epidemiology that accompanies transmission decline, in which transmission is increasingly driven by population subgroups whose behaviours place them at increased exposure. Conventional tools of malaria surveillance and response are likely not sufficient in many elimination settings for accessing high-risk population subgroups, such as mobile and migrant populations (MMPs), given their greater likelihood of asymptomatic infections, illegal risk behaviours, limited access to public health facilities, and high mobility including extended periods travelling away from home. More adaptive, targeted strategies are needed to monitor transmission and intervention coverage effectively in these groups. Much can be learned from HIV programmes’ experience with “second generation surveillance”, including how to rapidly adapt surveillance and response strategies to changing transmission patterns, biological and behavioural surveys that utilize targeted sampling methods for specific behavioural subgroups, and methods for population size estimation. This paper reviews the strategies employed effectively for HIV programmes and offers considerations and recommendations for adapting them to the malaria elimination context.

Spatial and space-time distribution of Plasmodium vivax and Plasmodium falciparum malaria in China, 2005-2014

BACKGROUND

Despite the declining burden of malaria in China, the disease remains a significant public health problem with periodic outbreaks and spatial variation across the country. A better understanding of the spatial and temporal characteristics of malaria is essential for consolidating the disease control and elimination programme. This study aims to understand the spatial and spatiotemporal distribution of Plasmodium vivax and Plasmodium falciparum malaria in China during 2005-2009.

METHODS

Global Moran's I statistics was used to detect a spatial distribution of local P. falciparum and P. vivax malaria at the county level. Spatial and space-time scan statistics were applied to detect spatial and spatiotemporal clusters, respectively.

RESULTS

Both P. vivax and P. falciparum malaria showed spatial autocorrelation. The most likely spatial cluster of P. vivax was detected in northern Anhui province between 2005 and 2009, and western Yunnan province between 2010 and 2014. For P. falciparum, the clusters included several counties of western Yunnan province from 2005 to 2011, Guangxi from 2012 to 2013, and Anhui in 2014. The most likely space-time clusters of P. vivax malaria and P. falciparum malaria were detected in northern Anhui province and western Yunnan province, respectively, during 2005-2009.

CONCLUSION

The spatial and space-time cluster analysis identified high-risk areas and periods for both P. vivax and P. falciparum malaria. Both malaria types showed significant spatial and spatiotemporal variations. Contrary to P. vivax, the high-risk areas for P. falciparum malaria shifted from the west to the east of China. Further studies are required to examine the spatial changes in risk of malaria transmission and identify the underlying causes of elevated risk in the high-risk areas.

Towards Malaria Elimination: Monitoring and Evaluation of the "1-3-7" Approach at the China-Myanmar Border

The surveillance and response system remains one of the biggest challenges to malaria elimination along the China-Myanmar border. In China, "1-3-7" approach was developed to guide elimination activities according to the National Malaria Elimination Program, which is a simplified set of targets that delineates responsibilities and actions. The time frame of the approach has been incorporated into the nationwide web-based disease reporting system: 1, case reporting within 1 day after diagnosis; 3, case investigation within 3 days; and 7, focus investigation and action within 7 days. Herein, the data on malaria cases in 2005-2014 and after the "1-3-7" implementation in 2013-2014 of the 18 counties at the China-Myanmar border are reviewed and analyzed. Results showed that the total cases decreased while the proportion of imported cases rose. The "1-3-7" was well executed, except for the "3" indicator, which was 96.3% accomplished on average in the 18 border counties, but needs to be further strengthened. More efforts are highlighted for timely and accurate case detection as well as proactive mapping of disease transmission hot spots to facilitate the elimination of border malaria.

Multi-epitope chimeric antigen used as a serological marker to estimate Plasmodium falciparum transmission intensity in the border area of China-Myanmar

Background

Following the decline of malaria transmission in many countries and regions, serological parameters have become particularly useful for estimating malaria transmission in low-intensity areas. This study evaluated a novel serological marker, Malaria Random Constructed Antigen-1 (M.RCAg-1), which contains 11 epitopes from eight Plasmodium falciparum antigens, as a tool for assessing malaria transmission intensity along the border area of China-Myanmar.

Method

Serum from Plasmodium falciparum and P. vivax patients was used to detect the properties of M.RCAg-1 and antibody responses. Cross-sectional surveys were conducted at the China-Myanmar border and in Hainan province in 2012 and 2013 using cluster sampling. Filter blood spot papers were collected from all participants. Antibodies against M.RCAg-1 were detected using indirect ELISA. The Mann–Whitney test and Spearman’s rank correlation test were performed to analyze antibody data. P. falciparum malaria transmission intensity was estimated using a catalytic conversion model based on the maximum likelihood of generating a community seroconversion rate (SCR).

Results

M.RCAg-1 was well-recognized by the naturally acquired anti-malaria antibodies in P. falciparum patients and had very limited cross-reactivity with P. vivax infection. The total amount of IgG antibodies was decreased with the decrease in parasitemia after taking medication and lasted several weeks. In a population survey, the antibody levels were higher in residents living close to the China-Myanmar border than those living in non-epidemic areas (P < 0.0001), but no significant difference was observed between residents from Hainan and non-epidemic areas. The calculated SCR was 0.0128 for Jieyangka, 0.004 for Susuzhai, 0.0047 for Qiushan, and 0.043 for Kayahe. The estimated exposure rate obtained from the anti-M.RCAg-1 antibody level correlated with traditional measures of transmission intensity derived from altitude.

Conclusion

Our study demonstrates that M.RCAg-1 is potentially useful as a serological indicator of exposure to P. falciparum malaria, especially for malaria surveillance in low transmission areas.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0194-x) contains supplementary material, which is available to authorized users.

Public awareness of malaria in the middle stage of national malaria elimination programme. A cross-sectional survey in rural areas of malaria-endemic counties, China

BACKGROUND

Remarkable progress in the elimination of malaria has been achieved by the Chinese government in the past 5 years. However, imported cases have increased rapidly, and it is a critical threat to the national malaria elimination programme. This study aims to investigate the current status of the public awareness of malaria in the middle stage of the national malaria elimination progress.

METHODS

A cross-sectional survey with multi-stage stratified randomized sampling was undertaken between June 2015 and March 2016. A total of 1321 residents from nine malaria-endemic counties, 27 townships and 81 villages were interviewed using a structured questionnaire.

RESULTS

The results showed 51.6 % of the respondents had sufficient malaria knowledge. The malaria awareness of the public in type I counties was better than that in type II, whereas that in type III was the lowest. Approximately 74.9 % of the respondents were aware of at least one form of prevention of malaria, and 85.2 % of them would seek treatment when suffering from malaria. However, the awareness of fever, chills, sweating as common symptoms of malaria were 53.4, 56.2 and 31.6 %, respectively. The level of malaria awareness of the at-risk population was similar to that of the general population, it seemingly increased along with age and declined with the distance away from township hospitals.

CONCLUSION

The public awareness of malaria needs to improve continuously. Health education campaigns should focus on basic malaria knowledge and cover target populations. The multi-sectoral or even international collaboration should be further intensified. Careful planning is required to ensure that scattered villages are incorporated into the malaria health promotion system to sustain elimination.

Economic cost analysis of malaria case management at the household level during the malaria elimination phase in The People's Republic of China

BACKGROUND

In China, malaria has been posing a significant economic burden on households. To evaluate malaria economic burden in terms of both direct and indirect costs has its meaning in improving the effectiveness of malaria elimination program in China.

METHODS

A number of study sites (eight counties in five provinces) were selected from the malaria endemic area in China, representing the different levels of malaria incidence, risk classification, economic development. A number of households with malaria cases (n = 923) were surveyed during the May to December in 2012 to collect information on malaria economic burden. Descriptive statistics were used to characterize the basic profiles of selected malaria cases in terms of their gender, age group, occupation and malaria type. The malaria economic costs were evaluated by direct and indirect costs. Comparisons were carried out by using the chi-square test (or Z-test) and the Mann-Whitney U test among malaria cases with reference to local/imported malaria patients, hospitalized/out patients, and treatment hospitals.

RESULTS

The average cost of malaria per case was 1 691.23 CNY (direct cost was 735.41 CNY and indirect cost was 955.82 CNY), which accounted for 11.1 % of a household's total income. The average costs per case for local and imported malaria were 1 087.58 CNY and 4271.93 CNY, respectively. The average cost of a malaria patient being diagnosed and treated in a hospital at the county level or above (3 975.43 CNY) was 4.23 times higher than that of malaria patient being diagnosed and treated at a village or township hospital (938.80 CNY).

CONCLUSION

This study found that malaria has been posing a significant economic burden on households in terms of direct and indirect costs. There is a need to improve the effectiveness of interventions in order to reduce the impact costs of malaria, especially of imported infections, in order to eliminate the disease in China.

Targeting populations at higher risk for malaria: a survey of national malaria elimination programmes in the Asia Pacific

Background

Significant progress has been made in reducing the malaria burden in the Asia Pacific region, which is aggressively pursuing a 2030 regional elimination goal. Moving from malaria control to elimination requires National Malaria Control Programmes (NMCPs) to target interventions at populations at higher risk, who are often not reached by health services, highly mobile and difficult to test, treat, and track with routine measures, and if undiagnosed, can maintain parasite reservoirs and contribute to ongoing transmission.

Methods

A qualitative, free-text questionnaire was developed and disseminated among 17 of the 18 partner countries of the Asia Pacific Malaria Elimination Network (APMEN).

Results

All 14 countries that responded to the survey identified key populations at higher risk of malaria in their respective countries. Thirteen countries engage in the dissemination of malaria-related Information, Education, and Communication (IEC) materials. Eight countries engage in diagnostic screening, including of mobile and migrant workers, military staff, and/or overseas workers. Ten countries reported distributing or recommending the use of long-lasting insecticide-treated nets (LLINs) among populations at higher risk with fewer countries engaging in other prevention measures such as indoor residual spraying (IRS) (two countries), spatial repellents (four countries), chemoprophylaxis (five countries), and mass drug administration (MDA) (three countries). Though not specifically tailored to populations at higher risk, 11 countries reported using mass blood surveys as a surveillance tool and ten countries map case data. Most NMCPs lack a monitoring and evaluation structure.

Conclusion

Countries in the Asia Pacific have identified populations at higher risk and targeted interventions to these groups but there is limited information on the effectiveness of these interventions. Platforms like APMEN offer the opportunity for the sharing of protocols and lessons learned related to finding, targeting and successfully clearing malaria from populations at higher risk. The sharing of programme data across borders may further strengthen national and regional efforts to eliminate malaria. This exchange of real-life experience is invaluable to NMCPs when scarce scientific evidence on the topic exists to aid decision-making and can further support NMCPs to develop strategies that will deliver a malaria-free Asia Pacific by 2030.

Targeting populations at higher risk for malaria: a survey of national malaria elimination programmes in the Asia Pacific

BACKGROUND

Significant progress has been made in reducing the malaria burden in the Asia Pacific region, which is aggressively pursuing a 2030 regional elimination goal. Moving from malaria control to elimination requires National Malaria Control Programmes (NMCPs) to target interventions at populations at higher risk, who are often not reached by health services, highly mobile and difficult to test, treat, and track with routine measures, and if undiagnosed, can maintain parasite reservoirs and contribute to ongoing transmission.

METHODS

A qualitative, free-text questionnaire was developed and disseminated among 17 of the 18 partner countries of the Asia Pacific Malaria Elimination Network (APMEN).

RESULTS

All 14 countries that responded to the survey identified key populations at higher risk of malaria in their respective countries. Thirteen countries engage in the dissemination of malaria-related Information, Education, and Communication (IEC) materials. Eight countries engage in diagnostic screening, including of mobile and migrant workers, military staff, and/or overseas workers. Ten countries reported distributing or recommending the use of long-lasting insecticide-treated nets (LLINs) among populations at higher risk with fewer countries engaging in other prevention measures such as indoor residual spraying (IRS) (two countries), spatial repellents (four countries), chemoprophylaxis (five countries), and mass drug administration (MDA) (three countries). Though not specifically tailored to populations at higher risk, 11 countries reported using mass blood surveys as a surveillance tool and ten countries map case data. Most NMCPs lack a monitoring and evaluation structure.

CONCLUSION

Countries in the Asia Pacific have identified populations at higher risk and targeted interventions to these groups but there is limited information on the effectiveness of these interventions. Platforms like APMEN offer the opportunity for the sharing of protocols and lessons learned related to finding, targeting and successfully clearing malaria from populations at higher risk. The sharing of programme data across borders may further strengthen national and regional efforts to eliminate malaria. This exchange of real-life experience is invaluable to NMCPs when scarce scientific evidence on the topic exists to aid decision-making and can further support NMCPs to develop strategies that will deliver a malaria-free Asia Pacific by 2030.

Assessment of the impact of the malaria elimination programme on the burden of disease morbidity in endemic areas of Iran

BACKGROUND

Controlling and preventive measures considerably reduced malaria incidence in Iran over the past few years, which confined the endemic areas to some regions in the southeastern Iran. The National Malaria Elimination Programme commenced in 2010. With regard to the presumption that the elimination programme interventions have accelerated the declining trend of malaria incidence across the endemic areas of Iran, the present study attempted to assess the effectiveness of the elimination programme by reviewing malaria incidence status, over a 14-year period, and comparing the trend of malaria incidence across malaria-endemic areas between the control and pre-elimination phase, and the elimination phase.

METHODS

A retrospective analysis of malaria surveillance data was conducted in a 14-year period (2001-2014), using multilevel Poisson regression. The epidemiological malaria maps and indicators also were developed and compared between the control and pre-elimination phase, and the elimination phase.

RESULTS

The mean of malaria incidence was 2.2 (1.7-2.7) for the entire study period. This rate was 3.4 (2.6-4.1) in the control and pre-elimination phase, and 0.41 (0.25-0.57) for the elimination phase. During the malaria elimination phase, the decline of annual malaria incidence had significantly accelerated and autochthonous cases had the greatest difference in malaria incidence decline (compared to the control and pre-elimination phase), whereas, falciparum cases had the lowest difference in malaria incidence decline, followed by non-Iranian and imported cases. Furthermore, there was a decline in Iranians to non-Iranians ratio and an increase in the ratios of over 15 to under 15, as well as male to female, in the elimination phase in comparison to the control and pre-elimination phase.

CONCLUSIONS

It seems that the decline of malaria transmission, which has been initiated over the past few years, has accelerated as a result of the elimination programme, and Iran is approaching the goals set regarding the elimination of this disease.

Epidemiologic features of overseas imported malaria in the People's Republic of China

Background

With the dramatic increase in international travel among Chinese people, the risk of malaria importation from malaria-endemic regions threatens the achievement of the malaria elimination goal of China.

Methods

Epidemiological investigations of all imported malaria cases were conducted in nine provinces of China from 1 Nov, 2013 to 30 Oct, 2014. Plasmodium species, spatiotemporal distribution, clinical severity, preventive measures and infection history of the imported malaria cases were analysed using descriptive statistics.

Results

A total of 1420 imported malaria cases were recorded during the study period, with P. falciparum (723 cases, 50.9 %) and P. vivax (629 cases, 44.3 %) being the two predominant species. Among them, 81.8 % of cases were in Chinese overseas labourers. The imported cases returned from 41 countries, mainly located in Africa (58.9 %) and Southeast Asia (39.4 %). About a quarter (25.5 %, 279/1094) of counties in the nine study provinces were affected by imported malaria cases. There were 112 cases (7.9 %) developing complicated malaria, including 12 deaths (case fatality rate: 0.8 %). Only 27.8 % of the imported cases had taken prophylactic anti-malarial drugs. While staying abroad, 27.7 % of the cases had experienced two or more episodes of malaria infection. The awareness of clinical manifestations and the capacity for malaria diagnosis were weak in private clinics and primary healthcare facilities.

Conclusions

Imported malaria infections among Chinese labourers, returned from various countries, poses an increasing challenge to the malaria elimination programme in China. The risk of potential re-introduction of malaria into inland malaria-free areas of China should be urgently addressed.

Risk Assessment of Malaria Prevalence in Ludian, Yongshan, and Jinggu Counties, Yunnan Province, After 2014 Earthquake Disaster

The objective of this study was to investigate malaria prevalence after the 2014 earthquakes in Ludian, Yongshan, and Jinggu counties, Yunnan Province, China. We collected and analyzed epidemiological data and made a risk assessment of transmission probability. From January 2005 to July 2015, 87 malaria cases were reported in the three counties, most of which (81.6%) occurred between 2005 and 2009, with five cases reported in Jinggu County between January 2014 and July 2015, of which one case was reported after the earthquake. In addition, no local transmission occurred in the three counties from 2010, and 95.5% of imported malaria occurred in patients who had returned from Myanmar. The townships of Lehong, Qingsheng, and Weiyuan were the main endemic areas in the three counties. The probability of malaria transmission in the three counties was low, but Jinggu County had a higher risk due to the existence of infected patients and an appropriate vector. With sporadic cases reported annually, close monitoring should continue to enhance early detection of a possible malaria outbreak.

Predicting malaria vector distribution under climate change scenarios in China: Challenges for malaria elimination

Projecting the distribution of malaria vectors under climate change is essential for planning integrated vector control activities for sustaining elimination and preventing reintroduction of malaria. In China, however, little knowledge exists on the possible effects of climate change on malaria vectors. Here we assess the potential impact of climate change on four dominant malaria vectors (An. dirus, An. minimus, An. lesteri and An. sinensis) using species distribution models for two future decades: the 2030 s and the 2050 s. Simulation-based estimates suggest that the environmentally suitable area (ESA) for An. dirus and An. minimus would increase by an average of 49% and 16%, respectively, under all three scenarios for the 2030 s, but decrease by 11% and 16%, respectively in the 2050 s. By contrast, an increase of 36% and 11%, respectively, in ESA of An. lesteri and An. sinensis, was estimated under medium stabilizing (RCP4.5) and very heavy (RCP8.5) emission scenarios. in the 2050 s. In total, we predict a substantial net increase in the population exposed to the four dominant malaria vectors in the decades of the 2030 s and 2050 s, considering land use changes and urbanization simultaneously. Strategies to achieve and sustain malaria elimination in China will need to account for these potential changes in vector distributions and receptivity.

Trends of imported malaria in China 2010-2014: analysis of surveillance data

Background

To describe the epidemiologic profile and trends of imported malaria, and to identify the populations at risk of malaria in China during 2010–2014.

Methods

This is a descriptive analysis of laboratory confirmed malaria cases during 2010–2014. Data were obtained from surveillance reports in the China Information System for Disease Control and Prevention (CISDCP). The distribution of imported malaria cases over the years was analysed with X² for trend analysis test. All important demographic and epidemiologic variables of imported malaria cases were analysed.

Results

Malaria incidence in general reduced greatly in China, while the proportion of Plasmodium falciparum increased threefold from 0.08 to 0.21 per 100,000 population during the period 2010–2014. Of a total 17,725 malaria cases reported during the study period, 11,331 (64 %) were imported malaria and included an increasing trend: 292 (6 %), 2103 (63 %), 2151 (84 %), 3881 (96 %), 2904 (97 %), respectively, (X² = 2110.70, p < 0.01). The majority of malaria cases (imported and autochthonous) were adult (16,540, 93 %), male (15,643, 88 %), and farming as an occupation (11,808, 66 %). Some 3027 (94 %) of imported malaria cases had labour-related travel history during the study period; 90 % (6340/7034) of P. falciparum infections were imported into China from Africa, while 77 % of Plasmodium vivax infections (2440/3183) originated from Asia.

Conclusions

Malaria elimination in China faces the challenge of imported malaria, especially imported P. falciparum. Malaria prevention activities should target exported labour groups given the increasing number of workers returning from overseas.

Effects of a malaria elimination program: a retrospective study of 623 cases from 2008 to 2013 in a Chinese county hospital near the China--Myanmar border

The southwestern region of China, along the Myanmar border, has accounted for the highest number of cases of imported malaria since China shifted from a malaria control program to an elimination strategy in 2010. We conducted a retrospective study, in which 623 medical charts were analyzed to provide an epidemiological characterization of malaria cases that were diagnosed and treated at the People's Hospital of Tengchong County (PHTC), located in southwestern China, from 2008 to 2013. Our aim was to understand the characteristics of malaria in this region, which is a high-endemic region with imported cases. The majority of patients were male (91.7%), and the average age was 32.4 years. Most of the patients (86.4%) had visited Myanmar; labor was the purpose of travel for 63.9% of the patients. Plasmodium vivax and Plasmodium falciparum were responsible for 53.8% and 34.9% of the infections, respectively. The number of hospitalized patients rose gradually from 2008 to 2010 and reached its peak in 2010 (191). After 2010, the number of hospitalized cases fell rapidly from 191 (2010) to 45 (2013), and the proportion of patients who lived in the forest and the number infected with P. falciparum also fell. In conclusion, the number of hospitalized patients in the southwestern region of China, Tengchong county, decreased after China implemented a malaria elimination strategy in 2010. However, migrant workers returning from Myanmar remained important contributors to cases of imported malaria. The management of imported malaria should be targeted by the malaria elimination program in China.

Malaria imported from Ghana by returning gold miners, China, 2013

During May-August 2013, a malaria outbreak comprising 874 persons in Shanglin County, China, was detected among 4,052 persons returning from overseas. Ghana was the predominant destination country, and 92.3% of malarial infections occurred in gold miners. Preventive measures should be enhanced for persons in high-risk occupations traveling to malaria-endemic countries.

Malaria imported from Ghana by returning gold miners, China, 2013

During May-August 2013, a malaria outbreak comprising 874 persons in Shanglin County, China, was detected among 4,052 persons returning from overseas. Ghana was the predominant destination country, and 92.3% of malarial infections occurred in gold miners. Preventive measures should be enhanced for persons in high-risk occupations traveling to malaria-endemic countries.

China's 1-3-7 surveillance and response strategy for malaria elimination: Is case reporting, investigation and foci response happening according to plan?

Background

The China’s 1-3-7 strategy was initiated and extensively adopted in different types of counties (geographic regions) for reporting of malaria cases within 1 day, their confirmation and investigation within 3 days, and the appropriate public health response to prevent further transmission within 7 days. Assessing the level of compliance to the 1-3-7 strategy at the county level is a first step towards determining whether the surveillance and response strategy is happening according to plan. This study assessed if the time-bound targets of the 1-3-7 strategy were being sustained over time. Such information would be useful to improve implementation of the 1-3-7 strategy in China.

Methods

This cross-sectional study involved country-wide programmatic data for the period January 1st 2013 to June 30th 2014. Data variables were extracted from the national malaria information system and included socio-demographic information, type of county, date of diagnosis, date of reporting, date of case investigation, case classification (indigenous, or imported, or unknown), focus investigation, date of reactive case detection (RACD), and date of indoor residual spraying (IRS). Summary statistics and proportions were used and comparisons between groups were assessed using the chi-square test. Level of significance was set at a P-value ≤ 0.05.

Results

Of a total of 5,688 malaria cases from 731 counties, there were 55 (1 %) indigenous cases (only in Type 1 and Type 2 counties) and 5,633 (99 %) imported cases from all types of counties. There was no delay in reporting malaria cases by type of county. In terms of case investigation, 97.5 % cases were investigated within 3 days with the proportion of delays (1.5 %) in type 2 counties, being significantly lower than type 1 counties (4.1 %). Regarding active foci, 96.4 % were treated by RACD and/or IRS.

Conclusions

The performance of 1-3-7 strategy was encouraging but identified some challenges that if addressed can further improve implementation.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-015-0089-2) contains supplementary material, which is available to authorized users.

Analysis of Malaria Epidemiological Characteristics in the People's Republic of China, 2004-2013

This study aims to explore and characterize the malaria-endemic situation and trends from 2004 to 2013, to provide useful evidence for subsequently more effective strategic planning of malaria elimination in China. A total of 256,179 confirmed malaria cases were recorded in this period, and 86.8% of them were reported during 2004-2008. Between 2004 and 2008, Plasmodium vivax was the major species (72.2%) of malaria parasite. Most cases (67.3%) were found in male, and mainly in the age group of 35-39 years. A total of 236 deaths resulting from malaria were reported and nearly half (45.3%) of them were in Yunnan province. In all, 204,760 local malaria (79.9%) and 51,419 imported malaria (20.1%) were observed during 2004-2013. However, afterward the proportion of imported malaria continuously increased from 2004 (16.2%) to 2013 (97.9%). Moreover, 9,285 imported malaria cases were recorded during 2011-2013 in China, of which 5,976 cases (64.4%) came back from Africa. Overall, China has made achievements in controlling malaria, the locally transmitted malaria significantly declined in the past decades, by which the incidence has achieved historically the lowest levels. On the other hand, imported malaria has increasingly become a severe threat to malaria elimination. Therefore, to prevent the reintroduction of malaria, surveillance systems need to be well planned and managed to ensure timely case detection and prompt response at the elimination stage.

Evaluation of the population structure and genetic diversity of Plasmodium falciparum in southern China

Background

Yunnan and Hainan provinces are the two major endemic regions for Plasmodiumfalciparum malaria in China. However, few studies have investigated the characteristics of this parasite. Therefore, this study aimed to evaluate the genetic diversity and population structure of P. falciparum to predict the geographic origin of falciparum malaria.

Methods

Thirteen highly polymorphic microsatellite loci were studied to estimate the genetic diversity and population structure of 425 P. falciparum isolates obtained from blood samples collected from Yunnan and Hainan provinces of South China. The isolates were analysed for genetic diversity, linkage disequilibrium, and population structure. The parasite populations were clustered into two subgroups (i.e., Yunnan and Hainan) and a classification algorithm was used to identify molecular markers for classifying the P. falciparum populations.

Results

All 13 microsatellite loci were highly polymorphic, with the number of alleles per locus varying from 5 to 20. The mean expected heterozygosity (He) in Yunnan and Hainan was 0.766 ± 0.036 and 0.677 ± 0.039, respectively, revealing a moderate high level of genetic diversity. Significant linkage disequilibrium was found for some regions of Yunnan (Lazan county and Xishuangbanna region) and Hainan (Dongfang city and Sanya city) province. According to the classification algorithm, a combination of three microsatellites could be used as a discriminatory marker to identify the origin of P. falciparum isolates.

Conclusions

The results on the genetic structure of P. falciparum populations from South China provide a basis for developing a genetic marker-based tool to trace the source of the parasite infections and consequently improve malaria control and elimination strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0786-0) contains supplementary material, which is available to authorized users.

Spatial, temporal, and spatiotemporal analysis of malaria in Hubei Province, China from 2004-2011

Background

Malaria remains a public health concern in Hubei Province despite the significant decrease in malaria incidence over the past decades. Furthermore, history reveals that malaria transmission is unstable and prone to local outbreaks in Hubei Province. Thus, understanding spatial, temporal, and spatiotemporal distribution of malaria is needed for the effective control and elimination of this disease in Hubei Province.

Methods

Annual malaria incidence at the county level was calculated using the malaria cases reported from 2004 to 2011 in Hubei Province. Geographical information system (GIS) and spatial scan statistic method were used to identify spatial clusters of malaria cases at the county level. Pure retrospective temporal analysis scanning was performed to detect the temporal clusters of malaria cases with high rates using the discrete Poisson model. The space-time cluster was detected with high rates through the retrospective space-time analysis scanning using the discrete Poisson model.

Results

The overall malaria incidence decreased to a low level from 2004 to 2011. The purely spatial cluster of malaria cases from 2004 to 2011 showed that the disease was not randomly distributed in the study area. A total of 11 high-risk counties were determined through Local Moran’s I analysis from 2004 to 2011. The method of spatial scan statistics identified different 11 significant spatial clusters between 2004 and 2011. The space-time clustering analysis determined that the most likely cluster included 13 counties, and the time frame was from April 2004 to November 2007.

Conclusions

The GIS application and scan statistical technique can provide means to detect spatial, temporal, and spatiotemporal distribution of malaria, as well as to identify malaria high-risk areas. This study could be helpful in prioritizing resource assignment in high-risk areas for future malaria control and elimination.

Preparedness for malaria resurgence in China: case study on imported cases in 2000-2012

Malaria is the most important parasitic protozoan infection that has caused serious threats to human health globally. China has had success in reducing the morbidity and mortality of malaria to the lowest level through sustained and large-scale interventions. Although the total number of malaria cases declined gradually, the burden of the imported malaria cases mainly from Southeast Asian and African countries has increased substantially since 2000, posing a severe threat to public health in China. This review explores and analyses the epidemiological characteristics of the imported malaria based on data from 2000 to 2012, in order to provide theoretical bases and insights into effective prevention, avoid the resurgence of malaria in malaria-susceptible areas and develop appropriate strategies to protect people's health in China. This review also intends to offer the useful information of innovative approaches and tools that are required for malaria elimination in various settings.

Surveillance and response to drive the national malaria elimination program

The national action plan for malaria elimination in China (2010-2020) was issued by the Chinese Ministry of Health along with other 13 ministries and commissions in 2010. The ultimate goal of the national action plan was to eliminate local transmission of malaria by the end of 2020. Surveillance and response are the most important components driving the whole process of the national malaria elimination programme (NMEP), under the technical guidance used in NMEP. This chapter introduces the evolution of the surveillance from the control to the elimination stages and the current structure of national surveillance system in China. When the NMEP launched, both routine surveillance and sentinel surveillance played critical role in monitoring the process of NMEP. In addition, the current response strategy of NMEP was also reviewed, including the generally developed "1-3-7 Strategy". More effective and sensitive risk assessment tools were introduced, which cannot only predict the trends of malaria, but also are important for the design and adjustment of the surveillance and response systems in the malaria elimination stage. Therefore, this review presents the landscape of malaria surveillance and response in China as well as their contribution to the NMEP, with a focus on activities for early detection of malaria cases, timely control of malaria foci and epidemics, and risk prediction. Furthermore, challenges and recommendations for accelerating NMEP through surveillance are put forward.

Feasibility and roadmap analysis for malaria elimination in China

To understand the current status of the malaria control programme at the county level in accordance with the criteria of the World Health Organisation, the gaps and feasibility of malaria elimination at the county and national levels were analysed based on three kinds of indicators: transmission capacity, capacity of the professional team, and the intensity of intervention. Finally, a roadmap for national malaria elimination in the People's Republic of China is proposed based on the results of a feasibility assessment at the national level.

China-Africa cooperation initiatives in malaria control and elimination

Malaria has affected human health globally with a significant burden of disease, and also has impeded social and economic development in the areas where it is present. In Africa, many countries have faced serious challenges in controlling malaria, in part due to major limitations in public health systems and primary health care infrastructure. Although China is a developing country, a set of control strategies and measures in different local settings have been implemented successfully by the National Malaria Control Programme over the last 60 years, with a low cost of investment. It is expected that Chinese experience may benefit malaria control in Africa. This review will address the importance and possibility of China–Africa collaboration in control of malaria in targeted African countries, as well as how to proceed toward the goal of elimination where this is technically feasible.

Establishing a China malaria diagnosis reference laboratory network for malaria elimination

BACKGROUND

In China, the prevalence of malaria has reduced dramatically due to the elimination programme. The continued success of the programme will depend upon the accurate diagnosis of the disease in the laboratory. The basic requirements for this are a reliable malaria diagnosis laboratory network and quality management system to support case verification and source tracking.

METHODS

The baseline information of provincial malaria laboratories in the China malaria diagnosis reference laboratory network was collected and analysed, and a quality-assurance activity was carried out to assess their accuracies in malaria diagnosis by microscopy using WHO standards and PCR.

RESULTS

By the end of 2013, nineteen of 24 provincial laboratories have been included in the network. In the study, a total of 168 staff were registered and there was no bias in their age, gender, education level, and position. Generally Plasmodium species were identified with great accuracy by microscopy and PCR. However, Plasmodium ovale was likely to be misdiagnosed as Plasmodium vivax by microscopy.

CONCLUSIONS

China has established a laboratory network for primary malaria diagnosis which will cover a larger area. Currently, Plasmodium species can be identified fairly accurately by microscopy and PCR. However, laboratory staff need additional trainings on accurate identification of P. ovale microscopically and good performance of PCR operations.