A framework for assessing local transmission risk of imported malaria cases

Background:A key issue in achieving and sustaining malaria elimination is the need to prevent local transmission arising from imported cases of malaria.The likelihood of this occurring depends on a range of local faaors,and these can be used to allocate resources to contain transmission.Therefore,a risk assessment and management strategy is required to identify risk indexes for malaria transmission when imported cases occur.These risks also need to be quantified and combined to give a weighted risk index score.This can then be used to allocate the resources to each administrative region to prevent transmission according to the degree of risk.Methods:A list of potential risk indexes were generated from a literature review,expert consultation and panel discussion.These were initially classified into 4 first-level indexes including infection source,transmitting conditions,population vulnerability and control capacity.Each of these was then expanded into more detailed second-level indexes.The Delphi method was then used to obtain expert opinion to review and revise these risk indexes over two consecutive rounds to quantify agreement among experts as to their level of importance.Risk indexes were included in the final Transmission Risk Framework if they achieved a weighted importance score≥4.The Analytic Hierarchy Process was then used to calculate the weight allocated to each of the final risk indexes.This was then used to create an assessment framework that can be used to evaluate local transmission risk in different areas.Results:Two rounds of Delphi consultation were conducted.Twenty-three experts were used at each round with 100%recovery rate of participant questionnaires.The coordination coefficients(W)for the two rounds of Delphi consultation were 0.341 and 0.423,respectively(P<0.05).Three first-level indexes and 13 second-level indexes were identified.The Analytic Hierarchy Process was performed to calculate the weight of the indexes.For the first-level indexes,infection source,transmitting conditions,and control capacity,the index weight was 0.5396,0.2970 and 0.1634 respectively.For the three top second-level indexes,number of imported malaria cases,Anopheles species,and awareness of timely medical visit of patient,the index weight was 03382,0.2475,and 0.1509 respectively.Conclusions:An indexed system of transmission risk assessment for imported malaria was established using the Delphi method and the Analytic Hierarchy Process.This was assessed to be an objective and practical tool for assessing transmission risk from imported cases of malaria into China.

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-affeaed 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 16733 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 c 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,respeaively.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.

Profile and determinants of delayed care-seeking and diagnosis among patients with imported malaria: a retrospective study in China, 2014–2021

Background: In areas where malaria has been eliminated, delayed care-seeking and diagnosis of imported malaria are constant threats. This study aimed to describe the profile and determinants of delayed care-seeking and diagnosis among patients with imported malaria in China.Methods: This retrospective study assessed surveillance data obtained from 2014 to 2021 in the Chinese provincial-level administrative divisions (PLADs) of Anhui, Henan, Hubei, and Zhejiang, and Guangxi. Epidemiological characteristics were analyzed using descriptive statistics. Furthermore, factors associated with delayed care-seeking and diagnosis among imported malaria cases were identified using multivariate logistic regression.Results: Overall, 11.81% and 30.08% of imported malaria cases had delays in seeking care and diagnosis, respectively. During the study period, there was a decreasing trend in the proportion of imported malaria cases with delayed care-seeking (χ^(2) = 36.099,P < 0.001) and diagnosis (χ^(2) = 11.395,P = 0.001). In multivariate analysis, independent risk factors associated with delayed care-seeking include PLADs (Guangxi as reference), consultations in high-level facilities for the first medical visit, infections with non-Plasmodium falciparum species, and older age. However, PLADs (Guangxi as reference), the purpose of traveling (labour as reference), and infections with non-P. falciparum species increased the risk of delayed diagnosis. Delayed care-seeking (adjusted odds ratio: 1.79,P = 0.001) and diagnosis (adjusted odds ratio: 1.62,P = 0.004) were risk factors for severe disease development.Conclusions: Based on this study’s findings, we strongly advocate for improved access to quality healthcare to reduce the rate of misdiagnosis at the first visit. Infections caused by non-P. falciparum species should be highlighted, and more sensitive and specific point-of-care detection methods for non-P. falciparum species should be developed and implemented. In addition, education programs should be enhanced to reach target populations at risk of malaria infection. All these factors may reduce delayed care-seeking and diagnosis of imported malaria.

First imported Plasmodium ovale malaria in Central America: Case report of a Guatemalan soldier and a call to improve its accurate diagnosis

The Mesoamerican Ministers of Health have set 2020 as the target for malaria elimination to be achieved in the region. Imported malaria cases are a potential threat to countries attempting elimination or working to prevent resurgence. We report the first imported Plasmodium ovale infection with molecular confirmation in Central America, which occurred in a Guatemalan soldier that had been deployed in Africa. The obstacles for its diagnosis using the standard microscopy technique and the need to improve its detection are discussed.

The need for preventive and curative services for malaria when the military is deployed in endemic overseas territories: a case study and lessons learned

Background: Sri Lanka has been free from indigenous malaria since November 2012 and received the WHO certificate for malaria-free status in September 2016. Due to increased global travel, imported malaria cases continue to be reported in the country. Military personnel returning home from international peace-keeping missions in malaria endemic countries represent a key risk group in terms of imported malaria. The present study intended to characterize the potential causes of a malaria outbreak among the Sri Lankan security forces personnel deployed in the Central African Republic(CAR).Methods: Data were collected from a cross-sectional survey distributed among Sri Lankan Air Force personnel who had returned from United Nations peace-keeping missions in the CAR region. A pre-tested questionnaire was used for the data collection, and focus group discussions were also conducted.Results: One hundred twenty male Air Force personnel were interviewed(out of a group of 122 officers and airmen). All participants were deployed in the CAR for 14 months and were aware of the existence of chemoprophylaxis against malaria. The majority of the subjects(92.5%, 111/120) also knew that prophylaxis should be started prior to departure. However, the regular use of chemoprophylaxis was reported by only 61.7%(74/120) of the sample. Overall, 30.8% of the participants(37/120) had 44 symptomatic episodes of malaria during deployment, and one person succumbed to severe malaria. All cases were associated with noncompliance with chemoprophylaxis.Conclusion: Better coordination with overseas healthcare services and the establishment of directly observed chemoprophylaxis may help to avoid similar outbreaks in the future.

Mathematical modeling of malaria transmission dynamics in humans with mobility and control states

Malaria importation is one of the hypothetical drivers of malaria transmission dynamics across the globe.Several studies on malaria importation focused on the effect of the use of conventional malaria control strategies as approved by the World Health Organization(WHO)on malaria transmission dynamics but did not capture the effect of the use of traditional malaria control strategies by vigilant humans.In order to handle the aforementioned situation,a novel system of Ordinary Differential Equations(ODEs)was developed comprising the human and the malaria vector compartments.Analysis of the system was carried out to assess its quantitative properties.The novel computational algorithm used to solve the developed system of ODEs was implemented and benchmarked with the existing Runge-Kutta numerical solution method.Furthermore,simulations of different vigilant conditions useful to control malaria were carried out.The novel system of malaria models was well-posed and epidemiologically meaningful based on its quantitative properties.The novel algorithm performed relatively better in terms of model simulation accuracy than Runge-Kutta.At the best model-fit condition of 98%vigilance to the use of conventional and traditional malaria control strategies,this study revealed that malaria importation has a persistent impact on malaria transmission dynamics.In lieu of this,this study opined that total vigilance to the use of the WHO-approved and traditional malaria management tools would be the most effective control strategy against malaria importation.

Epidemiological characterization of imported recurrent Plasmodium vivax and Plasmodium ovale in China,2013–2020

Background China has reached important milestones in the elimination of malaria.However,the numbers of imported recurrent cases of Plasmodium vivax and P.ovale are gradually increasing,which increases the risk of malaria re-establishment in locations where Anopheles mosquitoes exist.The aim of this study is to characterize the epidemiological profiles of imported recurrent P.vivax and P.ovale cases,quantifying the recurrence burden and guiding the development of appropriate public health intervention strategies.Methods Individual-level data of imported recurrent P.vivax and P.ovale cases were collected from 2013 to 2020 in China via the Parasitic Diseases Information Reporting Management System.Demographic characteristics,temporal and spatial distributions,and the interval from previous infection to recurrence were analyzed by SAS,ArcGIS and GraphPad Prism software,respectively,to explore the epidemiological profiles of imported recurrent cases.Results A total of 307 imported recurrent cases,including 179 P.vivax and 128 P.ovale cases,were recorded.The majority of cases occurred in males(P.vivax 91.1%,P.ovale 93.8%)and migrant workers(P.vivax 43.2%,P.ovale 44.7%).Individuals aged 30–39 years had the highest P.vivax and P.ovale recurrent infection rates,respectively.The number of imported recurrent cases of infection by these two malaria species increased from 2013 to 2018,and P.vivax infection showed well-defined seasonality,with two peaks in February and June,respectively.More than 90%of patients with recurrent cases did not receive radical treatment for previous infection.Most imported recurrent P.vivax cases were reported in Yunnan Province and were imported from Myanmar,Ethiopia,and Pakistan,while most recurrent P.ovale cases were reported in southern China and primarily imported from Cameroon,Ghana,and Nigeria.The intervals from previous malaria infection to recurrence among different continents were significantly different(P=0.0016)for P.vivax malaria but not for P.ovale malaria(P=0.2373).Conclusions The large number of imported recurrent cases has been a major challenge in the prevention of malaria re-establishment in China.This study provides evidence to guide the development of appropriate public health intervention strategies for imported recurrent P.vivax and P.ovale cases.