Shrinking the malaria map in China: measuring the progress of the National Malaria Elimination Programme

Factors affecting delays in seeking treatment among malaria patients during the pre-certification phase in China

BACKGROUND

Delays in malaria treatment can not only lead to severe and even life-threatening complications, but also foster transmission, putting more people at risk of infection. This study aimed to investigate the factors influencing treatment delays among malaria patients and their health-seeking behaviour.

METHODS

The medical records of 494 patients diagnosed with malaria from 6 different malaria-endemic provinces in China were analysed. A bivariate and multivariable regression model was used to investigate the association between delays in seeking treatment and various factors. A Sankey diagram was used to visualize the trajectories of malaria patients seeking medical care. Total treatment delays were categorized as patient delays and doctor delays.

RESULTS

The incidence of total delays in seeking malaria treatment was 81.6%, of which 28.4% were delayed by patients alone and 34.8% by doctors alone. The median time from the onset of symptoms to the initial healthcare consultation was 1 day. The median time from the initial healthcare consultation to the conclusive diagnosis was 2 day. After being subjected to multiple logistic regression analysis, living in central China was less likely to experience patient delays (OR = 0.43, 95% CI 0.24-0.78). The factors significantly associated with the lower likelihood of doctor delays included: age between 30 to 49 (OR = 0.43, 95% CI 0.23-0.81), being single/divorce/separated (OR = 0.48, 95% CI 0.24-0.95), first visiting a county-level health institution (OR = 0.25, 95% CI 0.14-0.45), first visiting a prefectural health institution (OR = 0.06, 95% CI 0.03-0.12) and first visiting a provincial health institution (OR = 0.05, 95%CI 0.02-0.12). Conversely, individuals with mixed infections (OR = 2.04, 95% CI 1.02-4.08) and those experiencing periodic symptoms (OR = 1.71, 95% CI 1.00-2.92) might face increased doctor delays. Furthermore, higher financial burden and complications were found to be associated with patient delays. Doctor delays, in addition to incurring these two consequences, were associated with longer hospital stays.

CONCLUSION

There was a substantial delay in access to health care for malaria patients before China was certified malaria free. Region, marital status, periodic symptoms and the level of health institutions were factors contributing to delays in treatment-seeking among malaria patients.

Seasonal prediction of the distribution of three major malaria vectors in China: Based on an ecological niche model

Against the backdrop of a global malaria epidemic that remains severe, China has eradicated indigenous malaria but still has to be alert to the risk of external importation. Understanding the distribution of vectors can provide an adequate and reliable basis for the development and implementation of vector control strategies. However, with the decline of malaria prevalence in recent years, the capacity of vector monitoring and identification has been greatly weakened. Here we have used new sampling records, climatic data, and topographic data to establish ecological niche models of the three main malaria vectors in China. The model results accurately identified the current habitat suitability areas for the three species of Anopheles and revealed that in addition to precipitation and temperature as important variables affecting the distribution of Anopheles mosquitoes, topographic variables also influenced the distribution of Anopheles mosquitoes. Anopheles sinensis is the most widespread malaria vector in China, with a wide region from the northeast (Heilongjiang Province) to the southwest (Yunnan Province) suitable for its survival. Suitable habitat areas for Anopheles lesteri are concentrated in the central, eastern, and southern regions of China. The suitable habitat areas of Anopheles minimus are the smallest and are only distributed in the border provinces of southern China. On this basis, we further assessed the seasonal variation in habitat suitability areas for these three major malaria vectors in China. The results of this study provide new and more detailed evidence for vector monitoring. In this new era of imported malaria prevention in China, regular reassessment of the risk of vector transmission is recommended.

Polymorphism of Drug Resistance Genes dhfr and dhps in Plasmodium falciparum Isolates among Chinese Migrant Workers Who Returned from Ghana in 2013

In 2013, an epidemic of falciparum malaria involving over 820 persons unexpectedly broke out in Shanglin County, Guangxi Zhuang Autonomous Region, China, after a large number of migrant workers returned from Ghana, where they worked as gold miners. Herein, we selected 146 isolates randomly collected from these patients to investigate the resistance characteristics of the parasite to sulfadoxine-pyrimethamine (SP) by screening mutations in the dhfr and dhps genes. All 146 isolates were successfully genotyped for dhps, and only 137 samples were successfully genotyped for dhfr. In the dhfr gene, point mutations occurred at three codons: 51 (83.2%, 114/137), 59 (94.9%, 130/137), and 108 (96.4%, 132/137). In the dhps gene, mutations occurred at four codons: 436 (36.3%, 53/146 for S436A, 0.7%, 1/146 for S436Y), 437 (95.2%, 139/146), 540 (3.4%, 5/146), and 613 (2.7%, 4/146). All 146 isolates had mutations in at least one codon, either within dhfr or dhps. Quadruple mutation I51R59N108/G437 (41.1%, 60/146) of partial or low resistance level was the most prevalent haplotype combination. Quintuple I51R59N108/G437E540 accounted for 2.1% (3/146). Sextuple I51R59N108/A436G437S613 was also found and accounted for 1.4% (2/146). A chronological assay incorporating two sets of resistance data from the studies of Duah and Amenga-Etego provided an overview of the resistance trend from 2003 to 2018. During this period, the results we obtained generally coincided with the total development tendency of SP resistance. It can be concluded that Plasmodium falciparum samples collected from Chinese migrant workers from Ghana presented prevalent but relatively partial or low resistance to SP. A chronological assay incorporating two sets of data around 2013 indicates that our results possibly reflect the SP resistance level of Ghana in 2013 and that the possibility of increased resistance exists. Therefore, reasonable drug use and management should be strengthened while also maintaining a continuous screening of resistance to SP. These findings also underscore the need to strengthen the prevention of malaria importation from overseas and focus on preventing its reintroduction and transmission in China.

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.

Establishing and applying an adaptive strategy and approach to eliminating malaria: practice and lessons learnt from China from 2011 to 2020

ABSTRACTOn 30 June 2021, China was certified malaria-free by the World Health Organization. In this study, the evolution, performance, outcomes, and impact of China's adaptive strategy and approach for malaria elimination from 2011 to 2020 were analysed using 10-year data. The strategy and approach focused on timely detection and rapid responses to individual cases and foci. Indigenous cases declined from 1,308 in 2011 to 36 in 2015, and the last one was reported from Yunnan Province in April 2016, although thousands of imported cases still occur annually. The "1-3-7" approach was implemented successfully between 2013 and 2020, with 100% of cases reported within 24 h, 94.5% of cases investigated within three days of case reporting, and 93.4% of foci responses performed within seven days. Additionally, 81.6% of patients attended the first healthcare visit within 1-3 days of onset and 58.4% were diagnosed as malaria within three days of onset, in 2017-2020. The adaptive strategy and approach, along with their universal implementation, are most critical in malaria elimination. In addition to strengthening surveillance on drug resistance and vectors and border malaria collaboration, a further adapted three-step strategy and the corresponding "3-3-7" model are recommended to address the risks of re-transmission and death by imported cases after elimination. China's successful practice and lessons learnt through long-term efforts provide a reference for countries moving towards elimination.

Spend wisely to eliminate malaria

The countries of the Greater Mekong subregion-Myanmar, Thailand, Laos, Cambodia, and Vietnam-have set a target of eliminating all Plasmodium falciparum malaria by 2025. Generous funding has been provided, principally by The Global Fund to Fight AIDS, Tuberculosis, and Malaria, to achieve this objective and thereby prevent the spread of artemisinin-resistant Plasmodium falciparum to India and Africa. As the remaining time to reach agreed targets is limited and future external funding is uncertain, it is important to be realistic about the future and spend what remaining funding is left, wisely. New, labour intensive, vertical approaches to malaria elimination (such as the 1-3-7 approach) should not be promoted as these are unproven, likely to be ineffective, costly, and unlikely to be sustainable in the most remote areas where malaria prevalence is highest. Instead, the focus should be on reducing the malaria burden more rapidly in the remaining localised high transmission foci with proven effective interventions, including mass drug administration. Well supported community-based health workers are the key operatives in controlling malaria, but their remit should be broadened to sustain the uptake of their services as malaria declines. This strategy is a sustainable evolution, which will improve rural health care while ensuring progress towards malaria elimination.

Surveillance of Plasmodium vivax transmission using serological models in the border areas of China-Myanmar

Background

To understand the Plasmodium vivax malaria transmission intensity and to assess the effectiveness of prevention and control measures taken along the China–Myanmar border, a catalytic model was used to calculate the seroconversion rate, an important indicator of malaria transmission intensity with high sensitivity, which is particularly useful in areas of low transmission.

Methods

Five counties in Yunnan Province bordering Myanmar were selected as survey sites, and subjects were obtained in each county by stratified random sampling in 2013–2014. Fingerstick blood was collected from each subject and tested for antibodies to P. vivax Merozoite Surface Protein 1-19 (PvMSP1-19) using indirect ELISA. A catalytic conversion model was used to assess the transmission intensity of P. vivax malaria based on the maximum likelihood of generating a community seroconversion rate.

Results

A total of 3064 valid blood samples were collected. Antibody levels were positively correlated with age. The seroconversion rate (SCR) values for each village were Luoping (0.0054), Jingqiao (0.0061), Longpen (0.0087), Eluo (0.0079), Banwang (0.0042) and Banbie (0.0046), respectively.

Conclusion

Overall, the intensity of P. vivax malaria transmission in the border areas of Yunnan Province is low and not entirely consistent across counties. Consecutive serological surveys are needed to provide a sensitive evaluation of transmission dynamics and can help to confirm areas where infection is no longer present.

Risk factors for the accuracy of the initial diagnosis of malaria cases in China: a decision-tree modelling approach

Background

Early accurate diagnosis and risk assessment for malaria are crucial for improving patients’ terminal prognosis and preventing them from progressing to a severe or critical stage. This study aims to describe the accuracy of the initial diagnosis of malaria cases with different characteristics and the factors that affect the accuracy in the context of the agenda for a world free of malaria.

Methods

A retrospective study was conducted on 494 patients admitted to hospitals with a diagnosis of malaria from January 2014 through December 2016. Descriptive statistics were calculated, and decision tree analysis was performed to predict the probability of patients who may be misdiagnosed.

Results

Of the 494 patients included in this study, the proportions of patients seeking care in county-level, prefecture-level and provincial-level hospitals were 27.5% (n = 136), 26.3% (n = 130) and 8.3% (n = 41), respectively; the proportions of patients seeking care in clinic, township health centre and Centres for Disease Control and Prevention were 25.9% (n = 128), 4.1% (n = 20), and 7.9% (n = 39), respectively. Nearly 60% of malaria patients were misdiagnosed on their first visit, and 18.8% had complications. The median time from onset to the first visit was 2 days (IQR: 0-3 days), and the median time from the first visit to diagnosis was 3 days (IQR: 0–4 days). The decision tree classification of malaria patients being misdiagnosed consisted of six categorical variables: healthcare facilities for the initial diagnosis, time interval between onset and initial diagnosis, region, residence type, insurance status, and age.

Conclusions

Insufficient diagnostic capacity of healthcare facilities with lower administrative levels for the first visit was the most important risk factor in misdiagnosing patients. To reduce diagnostic errors, clinicians, government decision-makers and communities should consider strengthening the primary care facilities, the time interval between onset and initial diagnosis, residence type, and health insurance status.

What sub-Saharan African countries can learn from malaria elimination in China

Malaria is one of the most devastating diseases plaguing the sub-Saharan African region since time immemorial. In spite of a global reduction in mortality rates, a significant proportion of deaths due to malaria is still accounted for in the region. China recently joined the 40 countries declared malaria free by the World Health Organization and became the first country in the WHO Western Pacific Region to be awarded the certification. We commented on the strategies employed by China to eliminate malaria, address challenges facing malaria control in sub-Saharan Africa, and derive lessons that could be learned in the sub-Saharan African context.

Tropical Medicine in China: Bibliometric Analysis Based on Web of Science (2010-2019)

Purpose

The current study quantitatively assessed research trends in tropical medicine in China via a bibliometric method, which used the Web of Science database to analyse the research-based literature related to tropical medicine published from 2010 to 2019.

Methods

Articles were analysed according to the output and research performance of institutes and countries that collaborated with China. Distribution of keywords was applied to evaluate research trends.

Results

Our findings showed that 3372 articles in the field of tropical medicine have been indexed under the Web of Science database during the past 10 years, indicating that studies pertaining to tropical medicine have been growing from 2010 to 2019. The Chinese Center for Disease Control and Prevention (China CDC) system, which published 549 articles on tropical medicine, may be considered as the flagship of tropical medicine in China. The United States ranked first in internationally collaborative articles with China. Furthermore, Parasite & Vectors, which published 707 papers, emerged as the top journal according to the number of publications.

Conclusions

This study highlights the key institutes and topics pertaining to tropical medicine research in China. Although there has been rapid progress in research on tropical medicine in China, some gaps still remain.

A retrospective analysis of malaria epidemiological characteristics in Yingjiang County on the China-Myanmar border

Yingjiang County, which is on the China–Myanmar border, is the main focus for malaria elimination in China. The epidemiological characteristics of malaria in Yingjiang County were analysed in a retrospective analysis. A total of 895 malaria cases were reported in Yingjiang County between 2013 and 2019. The majority of cases occurred in males (70.7%) and individuals aged 19–59 years (77.3%). Plasmodium vivax was the predominant species (96.6%). The number of indigenous cases decreased gradually and since 2017, no indigenous cases have been reported. Malaria cases were mainly distributed in the southern and southwestern areas of the county; 55.6% of the indigenous cases were reported in Nabang Township, which also had the highest risk of imported malaria. The “1–3–7” approach has been implemented effectively, with 100% of cases reported within 24 h, 88.9% cases investigated and confirmed within 3 days and 98.5% of foci responded to within 7 days. Although malaria elimination has been achieved in Yingjiang County, sustaining elimination and preventing the re-establishment of malaria require the continued strengthening of case detection, surveillance and response systems targeting the migrant population in border areas.

Spatial patterns of <em>Plasmodium vivax</em> transmission explored by multivariate auto-regressive state-space modelling - A case study in Baoshan Prefecture in southern China

The transition from the control phase to elimination of malaria in China through the national malaria elimination programme has focussed attention on the need for improvement of the surveillance- response systems. It is now understood that routine passive surveillance is inadequate in the parasite elimination phase that requires supplementation by active surveillance in foci where cluster cases have occurred. This study aims to explore the spatial clusters and temporal trends of malaria cases by the multivariate auto-regressive state-space model (MARSS) along the border to Myanmar in southern China. Data for indigenous cases spanning the period from 2007 to 2010 were extracted from the China's Infectious Diseases Information Reporting Management System (IDIRMS). The best MARSS model indicated that malaria transmission in the study area during 36 months could be grouped into three clusters. The estimation of malaria transmission patterns showed a downward trend across all clusters. The proposed methodology used in this study offers a simple and rapid, yet effective way to categorize patterns of foci which provide assistance for active monitoring of malaria in the elimination phase.

From control to elimination: a spatial-temporal analysis of malaria along the China-Myanmar border

Background

Malaria cases have declined significantly along the China-Myanmar border in the past 10 years and this region is going through a process from control to elimination. The aim of this study is to investigate the epidemiology of malaria along the border, will identify challenges in the progress from control to elimination.

Methods

National reported malaria cases from China and Myanmar, along with the data of 18 Chinese border counties and 23 townships in Myanmar were obtained from a web-based diseases information reporting system in China and the national malaria control program of Myanmar, respectively. Epidemiological data was analyzed, including the number of reported cases, annual parasite index and proportion of vivax infection. Spatial mapping of the annual parasite index (API) at county or township level in 2014 and 2018 was performed by ArcGIS. The relationship of malaria endemicity on both sides of the border was evaluated by regression analysis.

Results

The number of reported malaria cases and API declined in the border counties or townships. In 2014, 392 malaria cases were reported from 18 Chinese border counties, including 8.4% indigenous cases and 91.6% imported cases, while the highest API (0.11) was occurred in Yingjiang County. There have been no indigenous cases reported since 2017, but 164 imported cases were reported in 2018 and 97.6% were imported from Myanmar. The average API in 2014 in 23 Myanmar townships was significantly greater than that of 18 Chinese counties (P < 0.01). However, the API decreased significantly in Myanmar side from 2014 to 2018 (P < 0.01). The number of townships with an API between 0 and 1 increased to 15 in 2018, compared to only five in 2014, while still four townships had API > 10. Plasmodium vivax was the predominant species along the border. The number of reported malaria cases and the proportion of vivax infection in the 18 Chinese counties were strongly correlated with those of the 23 Myanmar townships (P < 0.05).

Conclusions

Malaria elimination is approaching along the China-Myanmar border. However, in order to achieve the malaria elimination in this region and prevent the re-establishment of malaria in China after elimination, continued political, financial and scientific commitment is required.

Confirmation of the absence of local transmission and geographic assignment of imported falciparum malaria cases to China using microsatellite panel

Background

Current methods to classify local and imported malaria infections depend primarily on patient travel history, which can have limited accuracy. Genotyping has been investigated as a complementary approach to track the spread of malaria and identify the origin of imported infections.

Methods

An extended panel of 26 microsatellites (16 new microsatellites) for Plasmodium falciparum was evaluated in 602 imported infections from 26 sub-Saharan African countries to the Jiangsu Province of People’s Republic of China. The potential of the 26 microsatellite markers to assign imported parasites to their geographic origin was assessed using a Bayesian method with Markov Chain Monte Carlo (MCMC) as implemented in the program Smoothed and Continuous Assignments (SCAT) with a modification to incorporate haploid genotype data.

Results

The newly designed microsatellites were polymorphic and are not in linkage disequilibrium with the existing microsatellites, supporting previous findings of high rate of recombination in sub-Saharan Africa. Consistent with epidemiology inferred from patients’ travel history, no evidence for local transmission was found; nearly all genetically related infections were identified in people who travelled to the same country near the same time. The smoothing assignment method assigned imported cases to their likely geographic origin with an accuracy (Angola: 59%; Nigeria: 51%; Equatorial Guinea: 40%) higher than would be achieved at random, reaching statistical significance for Angola and Equatorial Guinea.

Conclusions

Genotyping using an extended microsatellite panel is valuable for malaria case classification and programme evaluation in an elimination setting. A Bayesian method for assigning geographic origin of mammals based on genetic data was adapted for malaria and showed potential for identification of the origin of imported infections.

Rapid screening of Clonorchis sinensis infection: Performance of a method based on raw-freshwater fish-eating practice

Clonorchis sinensis infection is caused by ingestion of raw freshwater fish containing the infective larvae of Clonorchis sinensis. It is highly endemic in East Asia, especially in China. Selective chemotherapy of people who report habitual eating of raw freshwater fish is a control measure. As the performance of this screening technique has not yet been fully evaluated in China, a cross-sectional study was conducted, covering 17 counties in four major clonorchiasis-endemic provinces. About 1 000 participants were enrolled from each county. Fecal samples were collected and examined for helminth eggs and each person enrolled was asked about their practice with respect to eating raw freshwater fish. In total, 16 230 participants from 16 counties were finally included. The overall prevalence of C. sinensis infection was 10.8%, ranging from 0 to 53.7% in the 16 counties, while the percentage of inhabitants eating raw freshwater fish was 26.5%, ranging from 0 to 79.1%. The overall sensitivity and specificity of screening for C. sinensis infection in this approach was 82.3% and 80.3%, respectively, yielding a Youden's index of 0.6. The overall positive and negative likelihood ratios were 4.2 and 0.2, respectively, while the overall positive and negative predictive values were 33.5% and 97.4%, respectively. Furthermore, the sensitivity was higher with regard to high-intensity infections compared to light infections.

The contributions and achievements on malaria control and forthcoming elimination in China over the past 70 years by NIPD-CTDR

Although the past decades have seen a remarkable decrease in malaria-caused mortality and morbidity, the infection remains a significant challenge to global health. In the battle against malaria, China has gained notable feat and achievement since the 1940s through the efforts of several generations. Notably, China has not recorded a single indigenous malaria case since August 2016. The National Institute of Parasitic Diseases of the Chinese Center for Disease Control and Prevention (NIPD), as the only specialized institution for parasitic disease at the national level, has played a significant role in the malaria control, prevention, and elimination in China in the different historical periods. In order to transfer Chinese experiences on malaria control and elimination to other Low and Middle Income Countries (LMICs) and to improve global health collaboration, we have summarized and reviewed the contributions and achievements by the NIPD over the past 70 years, covering the epidemic situation; field investigation and laboratory experimental research on both parasite and vector; research and development on diagnostics, drugs, and insecticides; surveillance and response; technical and international. Support and cooperation. In addition, we also focus in particular on malaria retransmission risk, strategies on management of imported malaria cases and mobile populations, surveillance and response capacity to be maintained in post-elimination stage, challenges on diagnosis, drug resistance, and insecticide resistance as future concerns.

Distribution of malaria patients seeking care in different types of health facilities during the implementation of National Malaria Elimination Programme

BACKGROUND

China launched the National Malaria Elimination Programme (NMEP) in 2010 and set the goal that all health facilities should be able to diagnose malaria. Additionally, hospitals at all levels could treat malaria by 2015. To provide a reference for the control of imported malaria, a study was conducted on the distribution of malaria patients seeking care in different types of health facilities.

METHODS

There were two data sources. One was obtained through the Infectious Diseases Information Reporting Management System (IDIRMS), which only contained the name of health facilities and the number of cases. The other was obtained through multistage stratified cluster sampling. Descriptive statistical analysis was used to investigate the distribution of malaria patients attending different types of health facilities (hospitals, township hospitals, and Centers for Disease Control and Prevention), hospital tiers (county-level, prefecture-level, and provincial-level), and hospital levels (primary, secondary, and tertiary). Chi-square test was also used to compare the proportions of patients seeking care outside their current residence region between different types of hospitals. Point maps were drawn to visualize the spatial distribution of hospitals reporting malaria cases, and flow maps were created to show the spatial flow of malaria patients by using the ArcGIS software.

RESULTS

The proportions of malaria patients who sought care in hospitals, township hospitals, and Centers for Disease Control and Prevention were 81.7%, 14.7%, and 3.6%, respectively. For those who sought care in hospitals, the percentages of patients who sought care in provincial-level, prefecture-level and county-level hospitals were 17.4%, 60.5% and 22.1%, correspondingly; the proportions of patients who sought care in tertiary hospitals, secondary hospitals, and primary hospitals were 59.8%, 39.9%, and 0.3%, respectively. Moreover, the proportions of patients seeking care in hospitals within county and prefectural administrative areas were 18.2%, 63.4%, respectively.

CONCLUSION

During the implementation of NMEP, malaria patients tended to seek care in tertiary hospitals and prefecture-level hospitals, and more than half of patients could be treated in hospitals in prefecture-level areas. In the current phase, it is necessary to establish referral system from county-level hospitals to higher-level hospitals for malaria treatment.

Classification of induced malaria case in an elimination setting: investigation of transfusion-transmitted malaria cases

BACKGROUND

Since the National Malaria Elimination Action Plan was launched in China in 2010, local malaria transmission has decreased rapidly. Zero indigenous cases were reported since 2017. However, after 2010, the proportion of imported cases in China increased from 45.7% in 2010 to 99.9% in 2016, and almost all provinces of China have reported imported cases in recent years. Prevention of the reintroduction of malaria into China is crucial for the maintenance of its malaria-free status. Hence, it is of utmost importance to correctly identify the source of malaria infections within the country.

CASE INTRODUCTION AND RESPONSE

In 2016 and 2017, three laboratory-confirmed cases of malaria caused by Plasmodium falciparum were identified in patients with no previous travel history to endemic areas were reported in Jiangsu Province, China, where malaria due to P. falciparum was eliminated about 30 years ago. These were diagnosed after 41, 31 and 39 days of seeking treatment, respectively, and all of them had received blood transfusions. Further investigations indicated that two of the cases had received blood from foreign students (from Indonesia and Ghana), and the other had received blood from an individual who had worked in Equatorial Guinea. All three blood donors were traced, and found to be carrying asymptomatic P. falciparum infections by microscopic examination and PCR. Furthermore, five polymorphic microsatellite markers (C1M4, C4M62, C13M13, C14M17, and C13M63) were typed and used to link parasites from the donors with those of the transfusion-receiving patients.

CONCLUSIONS

Three transfusion-transmitted malaria cases were identified in China, all of which were due to the transfusion of blood donated by individuals who had contracted malaria outside the country. These cases can provide a reference for those faced with similar challenges in malaria case identification and classification in other regions. In addition, a stricter screening policy including the use of appropriate detection methods for malaria parasites should be developed and adopted for blood donation in regions undergoing malaria elimination.

Tracking progress towards malaria elimination in China: Individual-level estimates of transmission and its spatiotemporal variation using a diffusion network approach

In order to monitor progress towards malaria elimination, it is crucial to be able to measure changes in spatio-temporal transmission. However, common metrics of malaria transmission such as parasite prevalence are under powered in elimination contexts. China has achieved major reductions in malaria incidence and is on track to eliminate, having reporting zero locally-acquired malaria cases in 2017 and 2018. Understanding the spatio-temporal pattern underlying this decline, especially the relationship between locally-acquired and imported cases, can inform efforts to maintain elimination and prevent re-emergence. This is particularly pertinent in Yunnan province, where the potential for local transmission is highest. Using a geo-located individual-level dataset of cases recorded in Yunnan province between 2011 and 2016, we introduce a novel Bayesian framework to model a latent diffusion process and estimate the joint likelihood of transmission between cases and the number of cases with unobserved sources of infection. This is used to estimate the case reproduction number, Rc. We use these estimates within spatio-temporal geostatistical models to map how transmission varied over time and space, estimate the timeline to elimination and the risk of resurgence. We estimate the mean Rc between 2011 and 2016 to be 0.171 (95% CI = 0.165, 0.178) for P. vivax cases and 0.089 (95% CI = 0.076, 0.103) for P. falciparum cases. From 2014 onwards, no cases were estimated to have a Rc value above one. An unobserved source of infection was estimated to be moderately likely (p>0.5) for 19/ 611 cases and high (p>0.8) for 2 cases, suggesting very high levels of case ascertainment. Our estimates suggest that, maintaining current intervention efforts, Yunnan is unlikely to experience sustained local transmission up to 2020. However, even with a mean of 0.005 projected up to 2020, locally-acquired cases are possible due to high levels of importation.

Malaria in China: a longitudinal population-based surveillance study

This study aims to ascertain the long-term epidemic trends of malaria and evaluates the probability of achieving the eradication goal by 2020 in China. Data on malaria incidence and deaths were extracted from the China Information System for Disease Control and Prevention. The epidemic trends by sex, age and spatial distribution and predictions of malaria were estimated by using Joinpoint and Poisson regressions. From 1950 to 2016, 227 668 374 malaria cases were reported in China, with an annualised average incidence of 337.02 (336.98–337.07, 95% confidence interval (CI)) per 100 000 population. The incidence decreased with an average annual per cent change (AAPC) of −11.4% (−16.6 to −6.0). There were 36 085 malaria deaths, with an annualised average mortality of 0.534 (0.529–0.540) per 1 000 000 population. The mortality decreased with an AAPC of −8.7% (−13.7 to −3.4). The predicted number of malaria cases and deaths for 2020 is 2 562 and 10, respectively, and zero for indigenous cases. The disease burden of malaria dramatically decreased in China. Though, the goal of malaria elimination is realistic by 2020 in China, routine clinical and entomological surveillance should be continually conducted, especially for the cross-border areas and imported malaria cases.

The year 2020, a milestone in breaking the vicious cycle of poverty and illness in China

Marking the end of the five-year programme initiated by the Chinese Government to lift more than 70 million people out of poverty, the year 2020 is a milestone. Poverty alleviation has moved strongly forward in China and the major health indicators are now better than the average of all middle- and high-income countries. However, the dual burden of infectious and chronic diseases remains a challenge with respect to achieving the health target in the United Nations 2030 Agenda for sustainable development goals (SDGs). In 2015, about 44% of the poor population in China were impoverished by illness but already in 2018, multi-sectoral actions delivered by the Health-related Poverty Alleviation programme had reduced the number almost by half. In the past three years 15 million poor people (98% of the poor population) with infectious and chronic diseases had been treated and taken care of thanks to financial support through multiple health insurance schemes and other governmental subsidies. This article discusses the lessons learnt with regard to health-related poverty alleviation in China with special reference to those still remaining impoverished by illness. Consolidation of the achievements reached and provision of basic needs to those still disadvantaged and in poor health will require a major improvement of accessibility to, and affordability of, health services. The next step towards enhanced productivity and better living conditions will involve upgrading of the capacity of health professionals in the poor regions, promotion of coherent efforts in health-related poverty alleviation and rural revitalization measures. As an additional measure, data monitoring and research on health poverty alleviation should be strengthened as they are essential to generate the evidence and knowledge needed to support the move in the direction envisioned by the SDGs, and the new Healthy China 2030 programme.

From parasitic disease control to global health: New orientation of the National Institute of Parasitic Diseases, China CDC

As the only specialized institution for research and control of parasitic diseases at the national level in China for almost 70 years, the National Institute of Parasitic Diseases (NIPD) at the Chinese Center for Disease Control and Prevention (China CDC) has been instrumental in supporting the remarkable progress from high prevalence to transmission interruption or low endemicity of several diseases, lymphatic filariasis, malaria and schistosomiasis in particular. This has taken place through technical guidance, emergency response and scientific research as well as providing technical service, education, training, health promotion and international cooperation. With China's increasing involvement in international cooperation and the increased risk for (re)emerging tropical diseases in mind, the Chinese Government designated in 2017 a new Chinese Center for Tropical Disease Research to NIPD. Responding to the expanded responsibilities, the institute is scaling up its activities in several ways: from parasitic diseases to the wider area of tropical diseases; from disease control to disease elimination; from biological research to policy evidences accumulation; and from public health to global health. Based on this new vision and China's previous accomplishments in the areas mentioned, the institute is in a position to move forward with respect to global health and equitable development according to the central principles of the United Nations' Sustainable Development Goals.

Identification and analysis of vulnerable populations for malaria based on K-prototypes clustering

Malaria is a serious public health threat in Yunnan Province of China and has been frequently reported in some endemic regions, such as Tengchong County, with high morbidity. It is essential to analyze the characteristics of malaria cases and identify vulnerable populations. Previous studies about vulnerable populations have mostly used a statistical grouping method to count frequence from a single aspect rather than defined clustered groups. Based on descriptive analysis of the temporal variation and demographic structure of the populations with malaria infection, we used a k-prototypes clustering algorithm to cluster vulnerable populations in Tengchong County in three dimensions, according to sex, age, and occupation. The results indicated that a high incidence of malaria occurred mainly in young male farmers and young or middle-aged male migrant workers. Imported cases, low education level, lack of mosquito bite prevention, and risk behaviors contributed to the high malaria incidence in these groups. Double verification ensured the reliability of this method and reasonability of the results. In addition, we highlighted the importance of targeting prevention and control of malaria for vulnerable groups. We provided suggestions of policies and measures to be implemented by regional governments and at household and individual levels for farmers and migrant workers respectively. Using the k-prototypes clustering algorithm, we efficiently identified those populations at greatest risk of malaria infection. Our results may serve as scientific guidance for targeted malaria prevention and control in Yunnan Province.

Monitoring and evaluation of intervals from onset of fever to diagnosis before "1-3-7" approach in malaria elimination: a retrospective study in Shanxi Province, China from 2013 to 2018

BACKGROUND

China's 1-3-7 approach was extensively implemented to monitor the timeframe of case reporting, case investigation and foci response in the malaria elimination. However, activities before diagnosis and reporting (before '1') would counteract the efficiency of 1-3-7 approach but few data have evaluated this issue. This study aims to evaluate the timelines between onset of fever and diagnosis at healthcare facilities in Shanxi Province.

METHODS

Routine data were extracted from IDIRMS and NMISM database from 2013 to 2018. Time intervals between onset of fever and healthcare-seeking and between healthcare-seeking and diagnosis were calculated. Each of the documented malaria cases was geo-coded and paired to the county-level layers of polygon.

RESULTS

A total of 90 cases were reported in 2013-2018 in Shanxi Province, and 73% of cases reported at provincial health facilities. All malaria cases were imported from Africa (90%) and Southeast Asia (10%) especially around the Chinese Spring Festival (n = 46, 51%). The median days between fever and healthcare-seeking and between healthcare-seeking and diagnosis of malaria were 3 and 2, respectively.

CONCLUSIONS

The current "1-3-7" approach is well executed in Shanxi Province, but delays intervals observed in case finding before 1-3-7 approach occurred in all levels of facilities in Shanxi Province, which imply that more efforts are highlighted for timely case finding. Health education should be provided for improving awareness of healthcare-seeking, and various technical training aiming at the physicians should be carried out to improve diagnosis of malaria.

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.

Mutation Profile of pfdhfr and pfdhps in Plasmodium falciparum among Returned Chinese Migrant Workers from Africa

We evaluated markers of sulfadoxine-pyrimethamine (SP) resistance in Plasmodium falciparum among 254 returned migrant workers in China from Africa from 2013 to 2016. High prevalences of pfdhfr (97.2%) and pfdhps (96.5%) mutations were observed. The partially resistant genotype was homogeneously distributed in Africa with a modestly high prevalence (48%), whereas the super resistant genotype was only found in West Africa with a very low frequency (1.2%). The findings provided baseline data about the molecular markers of SP resistance.

Epidemiology of Imported Infectious Diseases, China, 2005-2016

Imported infectious diseases are becoming a serious public health threat in China. However, limited information concerning the epidemiologic characteristics of imported infectious diseases is available. In this study, we collected data related to imported infectious diseases in mainland China from the National Information Reporting System of Infectious Diseases and analyzed demographic, temporal, and spatial distributions. The number of types of imported infectious diseases reported increased from 2 in 2005 to 11 in 2016. A total of 31,740 cases of infectious disease were imported to mainland China during 2005–2016; most of them were found in Yunnan Province. The cases were imported mainly from Africa and Asia. As a key and effective measure, pretravel education should be strengthened for all migrant workers and tourists in China, and border screening, cross-border international cooperation, and early warning should be further improved.

Changing epidemiology and challenges of malaria in China towards elimination

Background

Historically, malaria had been a widespread disease in China. A national plan was launched in China in 2010, aiming to eliminate malaria by 2020. In 2017, no indigenous cases of malaria were detected in China for the first time. To provide evidence for precise surveillance and response to achieve elimination goal, a comprehensive study is needed to determine the changing epidemiology of malaria and the challenges towards elimination.

Methods

Using malaria surveillance data from 2011 to 2016, an integrated series of analyses was conducted to elucidate the changing epidemiological features of autochthonous and imported malaria, and the spatiotemporal patterns of malaria importation from endemic countries.

Results

From 2011 to 2016, a total of 21,062 malaria cases with 138 deaths were reported, including 91% were imported and 9% were autochthonous. The geographic distribution of local transmission have shrunk dramatically, but there were still more than 10 counties reporting autochthonous cases in 2013–2016, particularly in counties bordering with countries in South-East Asia. The importation from 68 origins countries had an increasing annual trend from Africa but decreasing importation from Southeast Asia. Four distinct communities have been identified in the importation networks with the destinations in China varied by origin and species.

Conclusions

China is on the verge of malaria elimination, but the residual transmission in border regions and the threats of importation from Africa and Southeast Asia are the key challenges to achieve and maintain malaria elimination. Efforts from China are also needed to help malaria control in origin countries and reduce the risk of introduced transmission.

Electronic supplementary material

The online version of this article (10.1186/s12936-019-2736-8) contains supplementary material, which is available to authorized users.

"Nine Dimensions": A multidisciplinary approach for community engagement in a complex postwar border region as part of the targeted malaria elimination in Karen/Kayin State, Myanmar

Background: In light of growing antimalarial drug resistance in Southeast Asia, control programmes have become increasingly focused on malaria elimination, composed of mass drug administration coupled with prompt diagnosis and treatment of symptomatic cases. The key to a successful elimination programme centres on high participation rates in targeted communities, often enhanced by community engagement (CE) efforts. Social science research was conducted to develop a conceptual framework used for CE activities in the Targeted Malaria Elimination programme, as a cross-border operation in Karen/Kayin State, Myanmar.

Methods: Data was collected from three main sources: (1) participant observation and semi-structured interviews of CE team members; (2) participant observation and semi-structured interviews with villagers; and (3) records of CE workshops with CE workers conducted as part of the TME programme.

Results: Interviews were conducted with 17 CE team members, with 10 participant observations and interviews conducted with villagers and a total of 3 workshops conducted over the course of this pilot programme in 4 villages (November 2013 to October 2014). Thematic analysis was used to construct the nine dimensions for CE in this complex, post-war region: i) history of the people; ii) space; iii) work; iv) knowledge about the world; v) intriguing obstacle (rumour); vi) relationship with the health care system; vii) migration; viii) logic of capitalism influencing openness; and ix) power relations.

Conclusions: Conducting CE for the Targeted Malaria Elimination programme was immensely complicated in Karen/Kayin State because of three key realities: heterogeneous terrains, a post-war atmosphere and cross-border operations. These three key realities constituted the nine dimensions, which proved integral to health worker success in conducting CE. Summary of this approach can aid in infectious disease control programmes, such as those using mass drug administration, to engender high rates of community participation.

"Nine Dimensions": A multidisciplinary approach for community engagement in a complex postwar border region as part of the targeted malaria elimination in Karen/Kayin State, Myanmar

Background: In light of growing antimalarial drug resistance in Southeast Asia, control programmes have become increasingly focused on malaria elimination, composed of mass drug administration coupled with prompt diagnosis and treatment of symptomatic cases. The key to a successful elimination programme centres on high participation rates in targeted communities, often enhanced by community engagement (CE) efforts. Social science research was conducted to develop a conceptual framework used for CE activities in the Targeted Malaria Elimination programme, as a cross-border operation in Karen/Kayin State, Myanmar. Methods: Data was collected from three main sources: (1) participant observation and semi-structured interviews of CE team members; (2) participant observation and semi-structured interviews with villagers; and (3) records of CE workshops with CE workers conducted as part of the TME programme. Results: Interviews were conducted with 17 CE team members, with 10 participant observations and interviews conducted with villagers and a total of 3 workshops conducted over the course of this pilot programme in 4 villages (November 2013 to October 2014). Thematic analysis was used to construct the nine dimensions for CE in this complex, post-war region: i) history of the people; ii) space; iii) work; iv) knowledge about the world; v) intriguing obstacle (rumour); vi) relationship with the health care system; vii) migration; viii) logic of capitalism influencing openness; and ix) power relations. Conclusions: Conducting CE for the Targeted Malaria Elimination programme was immensely complicated in Karen/Kayin State because of three key realities: heterogeneous terrains, a post-war atmosphere and cross-border operations. These three key realities constituted the nine dimensions, which proved integral to health worker success in conducting CE. Summary of this approach can aid in infectious disease control programmes, such as those using mass drug administration, to engender high rates of community participation.

Ready for malaria elimination: zero indigenous case reported in the People's Republic of China

BACKGROUND

Malaria was once one of the most serious public health problems in China. However, the disease burden has sharply declined and epidemic areas have shrunk after the implementation of an integrated malaria control and elimination strategy, especially since 2000. In this review, the lessons were distilled from the Chinese national malaria elimination programme and further efforts to mitigate the challenges of malaria resurgence are being discussed.

METHODS

A retrospective evaluation was performed to assess the changes in malaria epidemic patterns from 1950 to 2017 at national level. The malaria data before 2004 were collected from paper-based annual reports. After 2004, each of the different cases from the Infectious Diseases Information Reporting Management System (IDIRMS) was closely examined and scrutinized. An additional documenting system, the National Information Management System for Malaria, established in 2012 to document the interventions of three parasitic diseases, was also examined to complete the missing data from IDIRMS.

RESULTS

From 1950 to 2017, the occurrence of indigenous malaria has been steeply reduced, and malaria-epidemic regions have substantially shrunk, especially after the launch of the national malaria elimination programme. There were approximately 30 million malaria cases annually before 1949 with a mortality rate of 1%. A total of 5999 indigenous cases were documented from 2010 to 2016, with a drastic reduction of 99% over the 6 years (2010, n = 4262; 2016, n = 3). There were indigenous cases reported in 303 counties from 18 provinces in 2010, but only 3 indigenous cases were reported in 2 provinces nationwide in 2016. While in 2017, for the first time, zero indigenous case was reported in China, and only 7 of imported cases were in individuals who died of Plasmodium falciparum infection.

CONCLUSION

Malaria elimination in China is a country-led and country-owned endeavour. The country-own efforts were a clear national elimination strategy, supported by two systems, namely a case-based surveillance and response system and reference laboratory system. The country-led efforts were regional and inter-sectoral collaboration as well as sustained monitoring and evaluation. However, there are still some challenges, such as the maintenance of non-transmission status, the implementation of a qualified verification and assessment system, and the management of imported cases in border areas, through regional cooperation. The findings from this review can probably help improving malaria surveillance systems in China, but also in other elimination countries.

Surveillance of Antimalarial Resistance Pfcrt, Pfmdr1, and Pfkelch13 Polymorphisms in African Plasmodium falciparum imported to Shandong Province, China

Antimalarial drug resistance is a major public health problem in China. From 2012 to 2015, more than 75% of malaria cases in Shandong Province were P. falciparum returned from Africa. However, molecular marker polymorphisms of drug resistance in imported P. falciparum cases have not been evaluated. In this study, we analyzed polymorphisms of the Pfcrt, Pfmdr1, and Pfkelch13 genes in 282 P. falciparum cases returned from Africa to Shandong between 2012 and 2015. Among the isolates, polymorphisms were detected in codons 74–76 of Pfcrt and 86, 184, 1246 of Pfmdr1, among which K76T (36.6%) and Y184F (60.7%) were the most prevalent, respectively. Six Pfcrt haplotypes and 11 Pfmdr1 haplotypes were identified and a comparison was made on the prevalence of haplotypes among East Africa, West Africa, Central Africa and South Africa. One synonymous and 9 nonsynonymous mutations in Pfkelch13 were detected in the isolates (4.6%), among which a candidate artemisinin (ART) resistance mutation P553L was observed. The study establishes fundamental data for detection of chloroquine resistance (CQR) and ART resistance with molecular markers of the imported P. falciparum in China, and it also enriches the genetic data of antimalarial resistance for the malaria endemic countries in Africa.

Mobile population dynamics and malaria vulnerability: a modelling study in the China-Myanmar border region of Yunnan Province, China

BACKGROUND

The China-Myanmar border region presents a great challenge in malaria elimination in China, and it is essential to understand the relationship between malaria vulnerability and population mobility in this region.

METHODS

A community-based, cross-sectional survey was performed in five villages of Yingjiang county during September 2016. Finger-prick blood samples were obtained to identify asymptomatic infections, and imported cases were identified in each village (between January 2013 and September 2016). A stochastic simulation model (SSM) was used to test the relationship between population mobility and malaria vulnerability, according to the mechanisms of malaria importation.

RESULTS

Thirty-two imported cases were identified in the five villages, with a 4-year average of 1 case/year (range: 0-5 cases/year). No parasites were detected in the 353 blood samples from 2016. The median density of malaria vulnerability was 0.012 (range: 0.000-0.033). The average proportion of mobile members of the study population was 32.56% (range: 28.38-71.95%). Most mobile individuals lived indoors at night with mosquito protection. The SSM model fit the investigated data (χ² = 0.487, P = 0.485). The average probability of infection in the members of the population that moved to Myanmar was 0.011 (range: 0.0048-0.1585). The values for simulated vulnerability increased with greater population mobility in each village.

CONCLUSIONS

A high proportion of population mobility was associated with greater malaria vulnerability in the China-Myanmar border region. Mobile population-specific measures should be used to decrease the risk of malaria re-establishment in China.

The challenge of maintaining microscopist capacity at basic levels for malaria elimination in Jiangsu Province, China

Background

Local malaria transmission has decreased rapidly since the National Malaria Elimination Action Plan was launched in China in 2010. However, imported malaria cases from Africa and Southeast Asia still occur in China due to overseas laborers. Diagnosis by microscopy is the gold standard for malaria and is used in most hospitals in China. However, the current capacity of microscopists to manage malaria cases in hospitals and public health facilities to meet the surveillance needs to eliminate and prevent the reintroduction of malaria is unknown.

Methods

Malaria diagnoses were assessed by comparing the percentage of first visit and confirmed malaria diagnoses at Centers for Disease Control and Prevention (CDCs) and hospitals. The basic personnel information for public health departments and hospitals at different levels was investigated. The skills of microscopists for blood smear preparation and slide interpretation were also examined at the county and township levels.

Results

Inaccurate rate with 13.49% and 7.32%, respectively, in 2013 and 2014, from 341 and 355 reported cases from sub-provincial levels in Jiangsu province. Most of the 523 malaria cases reported in Nantong Prefecture from 2000 to 2014 involved patients who first visited county CDCs seeking treatment, however, none of these cases received confirmed diagnosis of malaria in townships or villages.The staff at county CDCs and hospitals with a higher education background performed better at making and interpreting blood smears than staff from townships.

Conclusions

The network for malaria elimination in an entire province has been well established. However, an insufficient capacity for malaria diagnosis was observed, especially the preparing and reading the blood smears at the township and village levels, which is a challenge to achieving and maintaining malaria elimination.

Mapping transmission foci to eliminate malaria in the People's Republic of China, 2010-2015: a retrospective analysis

BACKGROUND

China has initiated the National Malaria Elimination Action Plan, which aims to eliminate malaria by 2020. However, the transmission of malaria occurs sporadically or in distinct foci, which greatly hampers progress toward elimination in China and other countries. The object of this study was to foci categorization and evaluates whether the response met the requirements issued by the nation or WHO.

METHODS

Residual transmissions were investigated and located with fine spatial resolution mapping from parasitological confirmed malaria cases by use of routine national surveillance data. The "1-3-7" timeframes were monitored for each focus between 2012 and 2015. Each focus was identified, and the application of appropriate measures was evaluated.

RESULTS

A total of 5996 indigenous cases were recorded between 2010 and 2015; during this period, the number of cases declined by 99.1% (2010, n = 4262; 2015, n = 39). Most indigenous cases (92.5%) were reported in Anhui (n = 2326), Yunnan (n = 1373), Henan (n = 930), Hubei (n = 459), and Guizhou (n = 458). The temporal distribution showed that the indigenous malaria cases were clustered during the period of May to August. A total of 320 foci were carefully investigated and analyzed: 24 were active foci; 72, residual non-active foci; and 224 cleared-up foci. For the foci response evaluation, all the active foci were investigated within 7 days, while 80.2% of the residual non-active foci were responded within 7 days. In addition, reactive case detection (RACD) was carried out with 92.9% of the active foci and vector investigation carried out with 75%. For residual non-active foci, RACD was carried out with 83.2% and vector investigation with 78.2% of the foci.

CONCLUSIONS

This study used nationwide data to categorize foci in China and evaluate the response of these areas during the control and elimination phases. Our approach stratifies future control responses by identifying those locations where the elimination of endemic transmission is needed, such as in the counties at the China-Myanmar border and in Tibet. In addition, this study will help local CDC staff to reassess their needs and responses against different types of foci during the elimination and post-elimination phases.

Epidemiological characteristics of malaria from control to elimination in Hubei Province, China, 2005-2016

BACKGROUND

Hubei Province, China, has been operating a malaria elimination programme. This study aimed at investigating the epidemiologic characteristics of malaria in Hubei Province (2005-2016) to plan resource allocation for malaria elimination.

METHODS

Data on all malaria cases from 2005 to 2016 in all counties of Hubei Province were extracted from a web-based reporting system. The numbers of indigenous and imported cases during the disease control (2005-2010) and elimination (2011-2016) stages, as well as their spatiotemporal distribution, were compared.

RESULTS

A total of 8109 malaria cases were reported from 2005 to 2016 (7270 and 839 cases during the control and elimination stages, respectively). Between 2005 and 2010, indigenous malaria cases comprised the majority of total cases (7114/7270; 97.9%), and Plasmodium vivax malaria cases accounted for most malaria cases (5572/7270; 76.6%). No indigenous malaria cases have been reported in Hubei Province since 2013. Imported malaria cases showed a gradually increasing trend from 2011 to 2016, Plasmodium falciparum was the predominant species in these cases, and the number of counties with imported cases increased from 4 in 2005 to 47 in 2016. During the control and elimination stages, the most likely spatial clusters for indigenous cases included 13 and 11 counties, respectively. However, the cluster of indigenous malaria cases has not been identified since September 2011. For imported cases, the most likely cluster and three secondary clusters during both stages were identified.

CONCLUSIONS

Hubei Province has made significant achievements in controlling and eliminating malaria; however, the region now faces some challenges associated with the increasing number and distribution of imported malaria cases. Priorities for malaria elimination should include better management of imported malaria cases, prevention of secondary malaria transmission, and ensuring the sustainability of malaria surveillance.

ASGDB: a specialised genomic resource for interpreting Anopheles sinensis insecticide resistance

BACKGROUND

Anopheles sinensis is an important malaria vector in Southeast Asia. The widespread emergence of insecticide resistance in this mosquito species poses a serious threat to the efficacy of malaria control measures, particularly in China. Recently, the whole-genome sequencing and de novo assembly of An. sinensis (China strain) has been finished. A series of insecticide-resistant studies in An. sinensis have also been reported. There is a growing need to integrate these valuable data to provide a comprehensive database for further studies on insecticide-resistant management of An. sinensis.

RESULTS

A bioinformatics database named An. sinensis genome database (ASGDB) was built. In addition to being a searchable database of published An. sinensis genome sequences and annotation, ASGDB provides in-depth analytical platforms for further understanding of the genomic and genetic data, including visualization of genomic data, orthologous relationship analysis, GO analysis, pathway analysis, expression analysis and resistance-related gene analysis. Moreover, ASGDB provides a panoramic view of insecticide resistance studies in An. sinensis in China. In total, 551 insecticide-resistant phenotypic and genotypic reports on An. sinensis distributed in Chinese malaria-endemic areas since the mid-1980s have been collected, manually edited in the same format and integrated into OpenLayers map-based interface, which allows the international community to assess and exploit the high volume of scattered data much easier. The database has been given the URL: http://www.asgdb.org /.

CONCLUSIONS

ASGDB was built to help users mine data from the genome sequence of An. sinensis easily and effectively, especially with its advantages in insecticide resistance surveillance and control.

Mapping multiple components of malaria risk for improved targeting of elimination interventions

There is a long history of considering the constituent components of malaria risk and the malaria transmission cycle via the use of mathematical models, yet strategic planning in endemic countries tends not to take full advantage of available disease intelligence to tailor interventions. National malaria programmes typically make operational decisions about where to implement vector control and surveillance activities based upon simple categorizations of annual parasite incidence. With technological advances, an enormous opportunity exists to better target specific malaria interventions to the places where they will have greatest impact by mapping and evaluating metrics related to a variety of risk components, each of which describes a different facet of the transmission cycle. Here, these components and their implications for operational decision-making are reviewed. For each component, related mappable malaria metrics are also described which may be measured and evaluated by malaria programmes seeking to better understand the determinants of malaria risk. Implementing tailored programmes based on knowledge of the heterogeneous distribution of the drivers of malaria transmission rather than only consideration of traditional metrics such as case incidence has the potential to result in substantial improvements in decision-making. As programmes improve their ability to prioritize their available tools to the places where evidence suggests they will be most effective, elimination aspirations may become increasingly feasible.

Economic burden of malaria inpatients during National Malaria Elimination Programme: estimation of hospitalization cost and its inter-province variation

BACKGROUND

Apart from its direct impact on public health and well-being, malaria had placed significant socioeconomic burden on both individuals and whole health systems. This study was conducted to investigate the hospitalization cost of malaria and explore the inter-province variation during the National Malaria Elimination Programme in China.

METHODS

Information on medical expenditure for malaria treatment was extracted from inpatient medical records in Henan, Hainan and Guangxi Province. The costs were adjusted to the price in 2014 and converted to USD (United States Dollars). Non-parametric and parametric methods were employed to estimate hospitalization costs and non-parametric bootstrap method was used for the comparison of hospitalization costs among sample provinces and to estimate the uncertainty of differences in inter-province hospitalization costs.

RESULTS

The hospitalization cost and daily cost of 426 malaria inpatients were 929.8 USD and 143.12 USD respectively. The average length of stay was 11.95 days. The highest cost of hospitalization services occurred in tertiary hospitals (956 USD per episode). Whereas the lowest ones occurred in internal departments (424 USD). Medications, laboratory tests and supportive resources for treatment were the most important components of hospitalization costs, respectively responsible for 45.31, 24.70, and 20.09% of the total hospitalization costs. The hospitalization cost per episode in Henan Province was significantly higher than that in Hainan an in Guangxi Province, with incremental costs of 713 USD (95% confidence interval 419.70, 942.50) and of 735.58 USD (95% CI 606.50, 878.00), respectively. The differences in the daily costs between Henan and Hainan along with Guangxi provinces were 75.33 USD (95% CI 40.33, 96.67) and 93.56 USD (95% CI 83.58, 105.28), respectively.

CONCLUSIONS

Although the prevalence of malaria cases has considerably declined, the direct hospitalization costs of malaria in the household remain high and the inter-province variations need to be seriously considered in the formulation the further interventions regarding hospitalization cost control. This study suggests that economic risk protection mechanisms targeting at malaria inpatients should be redesigned. The drug price addition policy in public hospitals should be gradually reformed or abolished coupling with increasing government subsidies along with the charges for treatment services to reduce the hospitalization cost. The policy for cost control in the provincial hospitals should be implemented in comparison with the policy in other provinces, where the status of economic and geography are similar.

Anopheles Vectors in Mainland China While Approaching Malaria Elimination

China is approaching malaria elimination; however, well-documented information on malaria vectors is still missing, which could hinder the development of appropriate surveillance strategies and WHO certification. This review summarizes the nationwide distribution of malaria vectors, their bionomic characteristics, control measures, and related studies. After several years of effort, the area of distribution of the principal malaria vectors was reduced, in particular for Anopheles lesteri (synonym: An. anthropophagus) and Anopheles dirus s.l., which nearly disappeared from their former endemic regions. Anopheles sinensis is becoming the predominant species in southwestern China. The bionomic characteristics of these species have changed, and resistance to insecticides was reported. There is a need to update surveillance tools and investigate the role of secondary vectors in malaria transmission.

Risk assessment of malaria transmission at the border area of China and Myanmar

Background

In order to achieve the goal of malaria elimination, the Chinese government launched the National Malaria Elimination Programme in 2010. However, as a result of increasing cross-border population movements, the risk of imported malaria cases still exists at the border areas of China, resulting in a potential threat of local transmission. The focus of this paper is to assess the Plasmodium vivax incidences in Tengchong, Yunnan Province, at the border areas of China and Myanmar.

Methods

Time series of P. vivax incidences in Tengchong from 2006 to 2010 are collected from the web-based China Information System for Disease Control and Prevention, which are further separated into time series of imported and local cases. First, the seasonal and trend decomposition are performed on time series of imported cases using Loess method. Then, the impact of climatic factors on the local transmission of P. vivax is assessed using both linear regression models (LRM) and generalized additive models (GAM). Specifically, the notion of vectorial capacity (VCAP) is used to estimate the transmission potential of P. vivax at different locations, which is calculated based on temperature and rainfall collected from China Meteorological Administration.

Results

Comparing with Ruili County, the seasonal pattern of imported cases in Tengchong is different: Tengchong has only one peak, while Ruili has two peaks during each year. This may be due to the different cross-border behaviors of peoples in two locations. The vectorial capacity together with the imported cases and the average humidity, can well explain the local incidences of P. vivax through both LRM and GAM methods. Moreover, the maximum daily temperature is verified to be more suitable to calculate VCAP than the minimal and average temperature in Tengchong County.

Conclusion

To achieve malaria elimination in China, the assessment results in this paper will provide further guidance in active surveillance and control of malaria at the border areas of China and Myanmar.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-017-0322-2) contains supplementary material, which is available to authorized users.

A study on the epidemiological characteristics and infectious forecast model of malaria at Guangzhou Airport among Chinese returnees from Africa

BACKGROUND

Cross-border malaria transmission in China is a major component of Chinese imported malaria cases. Such cases mostly are travellers returning from malaria endemic countries in Africa. By investigating malaria infectious status among Chinese worker in Africa, this study analysed the malaria risk factors, in order to establish infectious forecast model.

METHODS

Chinese returnees data from Africa were collected at Guangzhou Baiyun International Airport, Guangzhou, China between August 2015 and March 2016 and were included in the cross-sectional and retrospective survey.

RESULTS

A total of 1492 respondents were included in the study with the majority consisting of junior middle school educated male. Most of them are manual and technical workers hired by companies, with average of 37.04 years of age. Overall malaria incidence rate of the population was 8.98% (134/1492), and there were no significant differences regarding age, gender, occupation, or team. Forecast model was developed on the basis of malaria risk factors including working country, local ecological environment type, work duration and intensity of mosquito bite prevention.

CONCLUSIONS

The survey suggested that malaria incidence was high among Chinese travellers who had worked in Africa countries of heavy malaria burden. Further research on the frequency and severity of clinical episodes among Chinese travellers having worked in Africa is needed.

Malaria in China, 2011-2015: an observational study

Objective

To ascertain the trends and burden of malaria in China and the costs of interventions for 2011–2015.

Methods

We analysed the spatiotemporal and demographic features of locally transmitted and imported malaria cases using disaggregated surveillance data on malaria from 2011 to 2015, covering the range of dominant malaria vectors in China. The total and mean costs for malaria elimination were calculated by funding sources, interventions and population at risk.

Findings

A total of 17 745 malaria cases, including 123 deaths (0.7%), were reported in mainland China, with 15 840 (89%) being imported cases, mainly from Africa and south-east Asia. Almost all counties of China (2855/2858) had achieved their elimination goals by 2015, and locally transmitted cases dropped from 1469 cases in 2011 to 43 cases in 2015, mainly occurring in the regions bordering Myanmar where Anopheles minimus and An. dirus are the dominant vector species. A total of United States dollars (US$) 134.6 million was spent in efforts to eliminate malaria during 2011–2015, with US$ 57.2 million (43%) from the Global Fund to Fight AIDS, Tuberculosis and Malaria and US$ 77.3 million (57%) from the Chinese central government. The mean annual investment (US$ 27 million) per person at risk (574 million) was US$ 0.05 (standard deviation: 0.03).

Conclusion

The locally transmitted malaria burden in China has decreased. The key challenge is to address the remaining local transmission, as well as to reduce imported cases from Africa and south-east Asia. Continued efforts and appropriate levels of investment are needed in the 2016–2020 period to achieve elimination.

Improving local health workers' knowledge of malaria in the elimination phase-determinants and strategies: a cross-sectional study in rural China

BACKGROUND

The current stage of malaria elimination in China requires experienced local health workers with sufficient knowledge of malaria who help to keep the public health system vigilant about a possible resurgence. However, the influencing factors of local health workers' knowledge level are not fully comprehended. This study aims to explore the factors with heavy impact on local health worker's knowledge of malaria and propose corresponding suggestions.

METHODS

Underpinned by stratified sampling method, a cross-sectional survey was carried out between November 2014 and April 2016. Chi square test was performed to identify the factors with potential influence on health workers' knowledge level of malaria. Bivariate logistic regression was employed to explore the relationship between the predictors and local health workers' knowledge level of malaria. Layered Chi square test was used to calculate the homogeneity of the interaction between training approaches and the percentage of participants with high-level knowledge.

RESULTS

The endemic type of county and type of organization played the most significant role in influencing local health workers' knowledge level regarding malaria in the sample population. The participants from Type 1 and Type 2 counties were 4.3 times (4.336 and 4.328, respectively) more likely to have high-level knowledge of malaria than those who work in Type 3 counties. The probability of having high-level knowledge amongst the participants from county-level facilities (county hospitals and CDCs) were more than 2.2 times higher than those who work in villages. Other socio-demographic factors, such as education and work experience, also affected one's knowledge regarding malaria. Amongst the six most-used training approaches, electronic material (OR = 2.356, 95% CI 1.112-4.989), thematic series (OR = 1.784, 95% CI 0.907-3.508) and supervision (OR = 2.788, 95% CI 1.018-7.632) were proven with significant positive impact on local health workers' knowledge of malaria.

CONCLUSION

Village doctors and who served in Type 3 counties were identified as the ones in urgent need of effective training. Three types of training approaches, including electronic material, thematic series and supervision, were proven to be effective in improving local health workers' knowledge. Nevertheless, the coverage of these training approaches was still limited. This study suggests expanding the coverage of training, especially the three particular types of training, to local health workers, particularly to the target populations (village doctors and who served in Type 3 counties). Online training, small group discussion and targeted skill development may be the directions for the future development of training programmes.

Genetic diversity and population structure of the primary malaria vector Anopheles sinensis (Diptera: Culicidae) in China inferred by cox1 gene

Background

Anopheles sinensis is a primary vector for Plasmodium vivax malaria in most regions of China. A comprehensive understanding of genetic variation and structure of the mosquito would be of benefit to the vector control and in a further attempt to contribute to malaria elimination in China. However, there is only inadequate population genetic data pertaining to An. sinensis currently.

Methods

Genetic variations and structure among populations of An. sinensis was examined and analyzed based on the nucleotide sequences of a 662 nt variable region of the mitochondrial cox1 gene among 15 populations from 20 collection sites in China.

Results

A total of 453 individuals in 15 populations were analyzed. The cox1 gene sequences were aligned, and 247 haplotypes were detected, 41 of these shared between populations. The range of haplotype diversity was from 0.709 (Yunnan) to 0.998 (Anhui). The genealogic network showed that the haplotypes were divided into two clusters, cluster I was at a high level of homoplasy, while cluster II included almost all individuals from the Yunnan population. The Yunnan population displayed a significantly high level of genetic differentiation (0.452−0.622) and a restricted gene flow with other populations. The pairwise F_ST values among other populations were lower. The AMOVA result showed that the percentage of variation within populations (83.83%) was higher than that among populations (16.17%). Mantel test suggested that geographical distance did not significantly contribute to the genetic differentiation (R² = 0.0125, P = 0.59). Neutral test and mismatch analysis results showed that the An. sinensis population has undergone demographic expansions.

Conclusions

Anopheles sinensis populations showed high genetic polymorphism by cox1 gene. The weak genetic structure may be a consequence of low genetic differentiation and high gene flow among populations, except the Yunnan samples. The Yunnan population was isolated from the other populations, gene flow limited by geographical distance and barriers. These findings will provide a theoretical basis for vector surveillance and vector control in China.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-017-2013-z) contains supplementary material, which is available to authorized users.