Plasmodium falciparum malaria importation from Africa to China and its mortality: an analysis of driving factors

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.

Imported and indigenous Plasmodium Vivax and Plasmodium Falciparum malaria in the Hubei Province of China, 2005-2019

BACKGROUND

The Hubei Province in China reported its last indigenous malaria case in September 2012, but imported malaria cases, particularly those related to Plasmodium vivax and Plasmodium falciparum, threaten Hubei's malaria-free status. This study investigated the epidemiological changes in P. vivax and P. falciparum malaria in this province to provide scientific evidence for preventing malaria resurgence.

METHODS

The prevalence, demographic characteristics, seasonal features, and geographical distribution of malaria were assessed using surveillance data and were compared across three stages: control stage (2005-2009) and elimination stages I (2010-2014) and II (2015-2019).

RESULTS

In 2005-2019, 8483 malaria cases were reported, including 5599 indigenous P. vivax cases, 275 imported P. vivax cases, 866 imported P. falciparum cases, and 1743 other cases. Imported P. falciparum cases accounted for 0.07% of all cases reported in 2005, but increased to 78.81% in 2019. Most imported P. vivax and P. falciparum malaria occurred among males, aged 21-60 years, during elimination stages I and II. The number of regions affected by imported P. falciparum and P. vivax increased markedly in Hubei from the control stage to elimination stage II. Overall, 1125 imported P. vivax and P. falciparum cases were detected from 47 other nations. Eight imported cases were detected from other provinces in China. From the control stage to elimination stage II, the number of cases of malaria imported from African countries increased, and that of cases imported from Southeast Asian countries decreased.

CONCLUSIONS

Although Hubei has achieved malaria elimination, it faces challenges in maintaining this status. Hence, imported malaria surveillance need to be strengthened to reduce the risk of malaria re-introduction.

Malaria Surveillance of Entry People During the COVID-19 Epidemic - Guangdong Province, China, October 2020-May 2021

What is already known about this topic?

Malaria control was affected by the coronavirus disease 2019 (COVID-19) pandemic. This study conducted active case finding for key flights and key populations to determine malaria transmission.

What is added by this report?

Surveillance for malaria was conducted for entry personnel coming from areas affected by malaria. It is estimated that at least 100,000 tests were conducted in Guangdong Province; 154 cases were confirmed during the surveillance.

What are the implications for public health practice?

To maintain the malaria elimination status, comprehensively maintaining a sensitive and effective surveillance response system is especially important.

Travel-related infection in Guangzhou, China,2009-2019

BACKGROUND

We analyzed the epidemiological characteristics of travel-related infectious diseases in reported Guangzhou between 2009 and 2019 to provide a scientific basis for prevention and control strategies.

METHOD

The infectious diseases report information system of China was mined for case reports, combined with clinical diagnosis records, and analyzed.

RESULTS

Between 2009 and 2019, 1478 cases of imported infectious diseases were reported in Guangzhou. Dengue fever accounted for 46.14%of cases and malaria accounted for 45.47% of cases. The patients with imported travel-related infection cases were mainly male (75.88%), Chinese (75.57%), and aged 20-45 years (83.01%). Cases increased from May each year, peaked between August and September, and declined rapidly after October. The main source areas of import were Africa and other countries in Asia.

CONCLUSIONS

Dengue fever and malaria are the main travel-related infection in Guangzhou, and are generally brought in by male Chinese workers. Intervention and health education in this population should be strengthened to prevent and control travel-related infection.

Genome-Wide Scans for Ghanaian Plasmodium falciparum Genes Under Selection From Local and Chinese Host Populations

Initial malarial infection mostly causes symptomatic illness in humans. Infection that is not fatal induces complete protection from severe illness and death, and thus complete protection from severe illness or death is granted with sufficient exposure. However, malaria parasite immunity necessitates constant exposure. Therefore, it is important to evaluate lowered immunity and recurrent susceptibility to symptomatic disease in lower transmission areas. We aimed to investigate selection pressure based on transmission levels, antimalarial drug use, and environmental factors. We whole genome sequenced (WGS) P. falciparum clinical samples from Chinese hosts working in Ghana and compared the results with the WGS data of isolates from native Ghanaians downloaded from pf3k. The P. falciparum samples were generally clustered according to their geographic origin, and Chinese imported samples showed a clear African origin with a slightly different distribution from the native Ghanaian samples. Moreover, samples collected from two host populations showed evidence of differences in the intensity of selection. Compared with native Ghanaian samples, the China-imported isolates exhibited a higher proportion of monoclonal infections, and many genes associated with RBC invasion and immune evasion were found to be under less selection pressure. There was no significant difference in the selection of drug-resistance genes due to a similar artemisinin-based combination therapy medication profile. Local selection of malarial parasites is considered to be a result of differences in the host immunity or disparity in the transmission opportunities of the host. In China, most P. falciparum infections were imported from Africa, and under these circumstances, distinct local selective pressures may be caused by varying acquired immunity and transmission intensity. This study revealed the impact of host switching on the immune system, and it may provide a better understanding of the mechanisms that enable clinical immunity to malaria.

Malaria Risk and Prevention in Asian Migrants to Angola

The number of Asian migrants working in sub-Saharan developing countries like Angola has been increasing. Their malaria risk, prevention, and care-seeking practices have not been characterized. A cross-sectional survey was conducted in 733 Chinese and Southeast Asian migrants in Angola. Respondents were interviewed and provided blood samples. Samples were analyzed to detect Plasmodium antigen and characterize host anti-Plasmodium response. Positive samples were genotyped using the pfs47 marker. Most respondents (72%; 95% CI: 68-75) reported using bed nets, but less than 1% reported using chemoprophylaxis. Depending on the assay, 1-4% of respondents had evidence of active malaria infection. By contrast, 55% (95% CI: 52-59) were seropositive for Plasmodium antibodies. Most infections were Plasmodium falciparum, but infection and/or exposure to Plasmodium vivax and Plasmodium malariae was also detected. Seroprevalence by time in Angola showed most exposure occurred locally. One respondent had sufficiently high parasitemia for pfs47 genotyping, which showed that the infection was likely locally acquired despite recent travel to home country. Asian migrants to Angola are at substantial risk of malaria. Employers should consider enhanced malaria prevention programs, including chemoprophylaxis; embassies should encourage prevention practices. Angolan healthcare workers should be aware of high malaria exposure in Asian migrants.

Epidemiology of Plasmodium falciparum Malaria and Risk Factors for Severe Disease in Hubei Province, China

This study aimed to describe the epidemiology of Plasmodium falciparum malaria and identify risk factors for severe disease in Hubei Province, China, using a case-based survey of retrospective data from 2013 to 2018. From 2013 to 2018, a total of 763 imported malaria cases were reported in Hubei Province; 69.2% (528/763) cases were caused by P. falciparum species. The proportion of malaria caused by P. falciparum increased from 66.7% in 2013 to 74.0% in 2018 (χ² = 21.378, P < 0.05). Plasmodium falciparum malaria was reported in 77 counties of Hubei Province. The majority of imported P. falciparum cases originated from Africa (98.9%, 522/528); 9.7% (51/528) of patients infected with P. falciparum developed severe malaria. Three deaths (case fatality rate: 0.6%) were related to imported P. falciparum malaria. Risk factors for severe malaria were being female (odds ratio [OR] = 3.593, 95% CI: 1.003-12.874), age ≥ 50 years (OR = 2.674, 95% CI: 1.269-5.634), > 3 days between symptom onset and diagnosis (OR = 2.383, 95% CI: 1.210-4.693), and the first-visit medical institution at the township level or lower (OR = 2.568, 95% CI: 1.344-4.908). Malaria prevention should be undertaken among high-risk groups, infection with P. falciparum should be detected early to prevent severe disease and death, and healthcare providers in health facilities at the township level should be trained on early recognition of malaria.

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.

Malaria Risk Map Using Spatial Multi-Criteria Decision Analysis along Yunnan Border During the Pre-elimination Period

In moving toward malaria elimination, finer scale malaria risk maps are required to identify hotspots for implementing surveillance–response activities, allocating resources, and preparing health facilities based on the needs and necessities at each specific area. This study aimed to demonstrate the use of multi-criteria decision analysis (MCDA) in conjunction with geographic information systems (GISs) to create a spatial model and risk maps by integrating satellite remote-sensing and malaria surveillance data from 18 counties of Yunnan Province along the China–Myanmar border. The MCDA composite and annual models and risk maps were created from the consensus among the experts who have been working and know situations in the study areas. The experts identified and provided relative factor weights for nine socioeconomic and disease ecology factors as a weighted linear combination model of the following: ([Forest coverage × 0.041] + [Cropland × 0.086] + [Water body × 0.175] + [Elevation × 0.297] + [Human population density × 0.043] + [Imported case × 0.258] + [Distance to road × 0.030] + [Distance to health facility × 0.033] + [Urbanization × 0.036]). The expert-based model had a good prediction capacity with a high area under curve. The study has demonstrated the novel integrated use of spatial MCDA which combines multiple environmental factors in estimating disease risk by using decision rules derived from existing knowledge or hypothesized understanding of the risk factors via diverse quantitative and qualitative criteria using both data-driven and qualitative indicators from the experts. The model and fine MCDA risk map developed in this study could assist in focusing the elimination efforts in the specifically identified locations with high risks.

Epidemiological Characteristics of Notifiable Infectious Diseases among Foreign Cases in China, 2004-2017

OBJECTIVE

We aimed to assess the features of notifiable infectious diseases found commonly in foreign nationals in China between 2004 and 2017 to improve public health policy and responses for infectious diseases.

METHODS

We performed a descriptive study of notifiable infectious diseases among foreigners reported from 2004 to 2017 in China using data from the Chinese National Notifiable Infectious Disease Reporting System (NNIDRIS). Demographic, temporal-spatial distribution were described and analyzed.

RESULTS

A total of 67,939 cases of 33 different infectious diseases were reported among foreigners. These diseases were seen in 31 provinces of China and originated from 146 countries of the world. The infectious diseases with the highest incidence number were human immunodeficiency virus (HIV) of 18,713 cases, hepatitis B (6,461 cases), hand, foot, and mouth disease (6,327 cases). Yunnan province had the highest number of notifiable infectious diseases in foreigners. There were different trends of the major infectious diseases among foreign cases seen in China and varied among provinces.

CONCLUSIONS

This is the first description of the epidemiological characteristic of notifiable infectious diseases among foreigners in China from 2004 to 2017. These data can be used to better inform policymakers about national health priorities for future research and control strategies.

Epidemiological characteristics of imported malaria in Shandong Province, China, from 2012 to 2017

Shandong Province, China, has been implementing a malaria elimination program. In this study, we analyzed the epidemiological characteristics of malaria imported into Shandong Province between 2012 and 2017 to provide scientific data for the elimination of malaria. In this epidemiological study, we examined the status of malaria in 2012–2017 in Shandong Province, China. Data on all cases of malaria were collected from the online Infection Diseases Monitor Information System to describe and statistically analyze the sources of infection, species of parasite, populations affected, regional distributions, incidence, and temporal distributions of malaria. In total, 1053 cases of malaria were reported in 2012–2017, and all of them were imported. Plasmodium falciparum was the predominant species (77.6%) in Shandong Province; P. vivax malaria accounted for 10.9% of the total number of cases, P. ovale malaria for 2.9%, and P. malariae malaria for 8.2%. Most patients were male (96.8%), most were aged 21–50 years (87.2%), and migrant laborers (77.2%) and workers (6.6%) were at highest risk. The origin of the largest number of imported cases was Africa (93.4%), followed by Asia (5.9%) and Oceania (0.4%). Most cases of imported malaria occurred in June each year and 70% of cases were recorded in six cities during the period of 2012–2017. It is necessary to strengthen malaria surveillance among workers returning home from Africa and Southeast Asia, and to conduct timely blood tests to diagnose and treat imported infections.

Imported Malaria in Countries where Malaria Is Not Endemic: a Comparison of Semi-immune and Nonimmune Travelers

The continuous increase in long-distance travel and recent large migratory movements have changed the epidemiological characteristics of imported malaria in countries where malaria is not endemic (here termed non-malaria-endemic countries). While malaria was primarily imported to nonendemic countries by returning travelers, the proportion of immigrants from malaria-endemic regions and travelers visiting friends and relatives (VFRs) in malaria-endemic countries has continued to increase. VFRs and immigrants from malaria-endemic countries now make up the majority of malaria patients in many nonendemic countries. Importantly, this group is characterized by various degrees of semi-immunity to malaria, resulting from repeated exposure to infection and a gradual decline of protection as a result of prolonged residence in non-malaria-endemic regions. Most studies indicate an effect of naturally acquired immunity in VFRs, leading to differences in the parasitological features, clinical manifestation, and odds for severe malaria and clinical complications between immune VFRs and nonimmune returning travelers. There are no valid data indicating evidence for differing algorithms for chemoprophylaxis or antimalarial treatment in semi-immune versus nonimmune malaria patients. So far, no robust biomarkers exist that properly reflect anti-parasite or clinical immunity. Until they are found, researchers should rigorously stratify their study results using surrogate markers, such as duration of time spent outside a malaria-endemic country.

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.

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.

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.

Are malaria elimination efforts on right track? An analysis of gains achieved and challenges ahead

Background

Malaria causes significant morbidity and mortality each year. In the past few years, the global malaria cases have been declining and many endemic countries are heading towards malaria elimination. Nevertheless, reducing the number of cases seems to be easy than sustained elimination. Therefore to achieve the objective of complete elimination and maintaining the elimination status, it is necessary to assess the gains made during the recent years.

Main text

With inclining global support and World Health Organisation (WHO) efforts, the control programmes have been implemented effectively in many endemic countries. Given the aroused interest and investments into malaria elimination programmes at global level, the ambitious goal of elimination appears feasible. Sustainable interventions have played a pivotal role in malaria contraction, however drug and insecticide resistance, social, demographic, cultural and behavioural beliefs and practices, and unreformed health infrastructure could drift back the progress attained so far. Ignoring such impeding factors coupled with certain region specific factors may jeopardise our ability to abide righteous track to achieve global elimination of malaria parasite. Although support beyond the territories is important, but well managed integrated vector management approach at regional and country level using scrupulously selected area specific interventions targeting both vector and parasite along with the community involvement is necessary. A brief incline in malaria during 2016 has raised fresh perturbation on whether elimination could be achieved on time or not.

Conclusions

The intervention tools available currently can most likely reduce transmission but clearing of malaria epicentres from where the disease can flare up any time, is not possible without involving local population. Nevertheless maintaining zero malaria transmission and checks on malaria import in declared malaria free countries, and further speeding up of interventions to stop transmission in elimination countries is most desirable. Strong collaboration backed by adequate political and financial support among the countries with a common objective to eliminate malaria must be on top priority. The present review attempts to assess the progress gained in malaria elimination during the past few years and highlights some issues that could be important in successful malaria elimination.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0524-x) contains supplementary material, which is available to authorized users.

Severe Plasmodium vivax malaria, HIV, tuberculosis co-infection in a Sri Lankan traveller: case management and challenges during the prevention of malaria reintroduction phase

Background

The country received malaria-free certification from WHO in September 2016, becoming only the second country in the WHO South East Asia region to be declared malaria-free. Imported malaria cases continue to be reported, with 278 cases reported between 2013 and 2017. The diagnosis of a severe Plasmodium vivax patient co-infected with HIV and tuberculosis is discussed with an overview of the rapid response mounted by the Anti Malaria Campaign (AMC), Sri Lanka.

Case presentation

A Sri Lankan gem miner who returned from Madagascar on the 6th of April 2018 presented to a private hospital for a malaria diagnostic test on the 21st April, 2 days after the onset of fever. He came on his own for this test due to the awareness he had regarding the risk of imported malaria. As the patient was positive for P. vivax malaria, he was admitted to a government hospital for further management. The patient had features of severe malaria upon admission with a systolic BP < 80 mmHg and thrombocytopaenia (38,000 cells/mm³). Treatment with IV artesunate was initiated immediately and management was carried out rapidly and efficiently by the clinicians with guidance from the staff of the AMC headquarters, which resulted in a rapid recovery of the patient. IV artesunate was followed by a course of artemether plus lumefantrine and the blood smear was negative for malaria by the 2nd day. A 14-day course of primaquine was commenced after excluding a G6PD deficiency. Due to an accidental needle stick injury of a health care worker attending on the patient was tested for HIV and subsequently tuberculosis and was found to be positive for both infections. The patient was discharged on the 1st of May with instructions for follow up visits for malaria. Management of the HIV and tuberculosis infections was attended to by the clinicians and staff of the appropriate disease control programmes (i.e. the national STD/AIDS Control Programme in Sri Lanka and the National Programme for tuberculosis control and chest diseases).

Conclusions

It is important to consider comorbid conditions and immunosuppression when a patient with a benign form of malaria presents with severe manifestations. Measures should be strengthened to prevent importation of diseases, such as malaria and AIDS through migrant workers who return from high-risk countries.

Seasonal and interannual risks of dengue introduction from South-East Asia into China, 2005-2015

Due to worldwide increased human mobility, air-transportation data and mathematical models have been widely used to measure risks of global dispersal of pathogens. However, the seasonal and interannual risks of pathogens importation and onward transmission from endemic countries have rarely been quantified and validated. We constructed a modelling framework, integrating air travel, epidemiological, demographical, entomological and meteorological data, to measure the seasonal probability of dengue introduction from endemic countries. This framework has been applied retrospectively to elucidate spatiotemporal patterns and increasing seasonal risk of dengue importation from South-East Asia into China via air travel in multiple populations, Chinese travelers and local residents, over a decade of 2005-15. We found that the volume of airline travelers from South-East Asia into China has quadrupled from 2005 to 2015 with Chinese travelers increased rapidly. Following the growth of air traffic, the probability of dengue importation from South-East Asia into China has increased dramatically from 2005 to 2015. This study also revealed seasonal asymmetries of transmission routes: Sri Lanka and Maldives have emerged as origins; neglected cities at central and coastal China have been increasingly vulnerable to dengue importation and onward transmission. Compared to the monthly occurrence of dengue reported in China, our model performed robustly for importation and onward transmission risk estimates. The approach and evidence could facilitate to understand and mitigate the changing seasonal threat of arbovirus from endemic regions.

Travel-related infections in mainland China, 2014-16: an active surveillance study

BACKGROUND

Transmission of infection through international travel is a growing health issue, and the frequency of imported infection is increasing in China. We aimed to quantify the total number of infections imported into mainland China by arriving travellers.

METHODS

We actively surveyed arriving travellers at all 272 international entry-exit ports in mainland China. Suspected cases were detected through fever screening, medical inspection, self-declaration, and reporting by on-board staff. Participants completed a standardised questionnaire with questions about demographics, their travel itinerary (including detailed information about all countries or regions visited), and clinical manifestations. Nasopharyngeal swabs, sputum samples, faecal samples, vomitus, blood, and serum were collected as appropriate for diagnoses. Diagnosis was made by specific laboratory tests according to the national technical guidelines. Infections were classified as respiratory, gastrointestinal, vector-borne, blood-transmitted and sex-transmitted, or mucocutaneous. We divided arriving travellers into two groups: travellers coming from countries other than China, and travellers coming from Hong Kong, Macau, and Taiwan. We integrated surveillance data for 2014-16, calculated incidences of travel-related infections, and compared the frequency of infections among subgroups.

FINDINGS

Between Jan 1, 2014, and Dec 31, 2016, 22 797 cases were identified among 805 993 392 arriving travellers-an overall incidence of 28·3 per million. 45 pathogens were detected in participants: 18 respiratory (19 662 cases), ten gastrointestinal (189 cases), seven vector-borne (831 cases), seven blood-transmitted and sex-transmitted (1531 cases), and three mucocutaneous (584 cases). Both the overall number and incidence of infection were more than five times higher in 2016 than in 2014. Case numbers and incidences also varied substantially by province, autonomous region, and municipality. Overall, 17 643 (77%) infections were detected by fever screening, but 753 (49%) blood-transmitted and sex-transmitted infections were identified through medical inspection. 14 305 (73%) cases of respiratory infection and 96 (51%) of gastrointestinal infections were in tourists. Tuberculosis, hepatitis A virus, vector-borne, and blood-transmitted and sex-transmitted infections were common among Chinese labourers who worked abroad. Dengue and malaria were most commonly diagnosed in travellers arriving from Africa. 12 126 (93%) of the 12 985 cases arriving from Hong Kong, Macau, or Taiwan were respiratory infections. Hand, foot, and mouth disease accounted for 2·90% of infections in travellers from Hong Kong, Macau, or Taiwan and 0·31% of infections in international travellers.

INTERPRETATION

This report is the first to characterise the profile of travel-related infections among arriving travellers in mainland China. Our findings should increase public awareness of the potential risk of imported infections, and help health-care providers to make evidence-based health recommendations to travellers.

FUNDING

The Natural Science Foundation of 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.

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.

Association between malaria incidence and meteorological factors: a multi-location study in China, 2005-2012

This study aims to investigate the climate-malaria associations in nine cities selected from malaria high-risk areas in China. Daily reports of malaria cases in Anhui, Henan, and Yunnan Provinces for 2005-2012 were obtained from the Chinese Center for Disease Control and Prevention. Generalized estimating equation models were used to quantify the city-specific climate-malaria associations. Multivariate random-effects meta-regression analyses were used to pool the city-specific effects. An inverted-U-shaped curve relationship was observed between temperatures, average relative humidity, and malaria. A 1 °C increase of maximum temperature (T max) resulted in 6·7% (95% CI 4·6-8·8%) to 15·8% (95% CI 14·1-17·4%) increase of malaria, with corresponding lags ranging from 7 to 45 days. For minimum temperature (T min), the effect estimates peaked at lag 0 to 40 days, ranging from 5·3% (95% CI 4·4-6·2%) to 17·9% (95% CI 15·6-20·1%). Malaria is more sensitive to T min in cool climates and T max in warm climates. The duration of lag effect in a cool climate zone is longer than that in a warm climate zone. Lagged effects did not vanish after an epidemic season but waned gradually in the following 2-3 warm seasons. A warming climate may potentially increase the risk of malaria resurgence in China.

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.