The geography of imported malaria to non-endemic countries: a meta-analysis of nationally reported statistics

Modelling the spatial risk of malaria through probability distribution of Anopheles maculipennis s.l. and imported cases

Malaria remains one of the most important infectious diseases globally due to its high incidence and mortality rates. The influx of infected cases from endemic to non-endemic malaria regions like Europe has resulted in a public health concern over sporadic local outbreaks. This is facilitated by the continued presence of competent Anopheles vectors in non-endemic countries.We modelled the potential distribution of the main malaria vector across Spain using the ensemble of eight modelling techniques based on environmental parameters and the Anopheles maculipennis s.l. presence/absence data collected from 2000 to 2020. We then combined this map with the number of imported malaria cases in each municipality to detect the geographic hot spots with a higher risk of local malaria transmission.The malaria vector occurred preferentially in irrigated lands characterized by warm climate conditions and moderate annual precipitation. Some areas surrounding irrigated lands in northern Spain (e.g. Zaragoza, Logroño), mainland areas (e.g. Madrid, Toledo) and in the South (e.g. Huelva), presented a significant likelihood of A. maculipennis s.l. occurrence, with a large overlap with the presence of imported cases of malaria.While the risk of malaria re-emergence in Spain is low, it is not evenly distributed throughout the country. The four recorded local cases of mosquito-borne transmission occurred in areas with a high overlap of imported cases and mosquito presence. Integrating mosquito distribution with human incidence cases provides an effective tool for the quantification of large-scale geographic variation in transmission risk and pinpointing priority areas for targeted surveillance and prevention.

Modeling the Regional Distribution of International Travelers in Spain to Estimate Imported Cases of Dengue and Malaria: Statistical Inference and Validation Study

BACKGROUND

Understanding the patterns of disease importation through international travel is paramount for effective public health interventions and global disease surveillance. While global airline network data have been used to assist in outbreak prevention and effective preparedness, accurately estimating how these imported cases disseminate locally in receiving countries remains a challenge.

OBJECTIVE

This study aimed to describe and understand the regional distribution of imported cases of dengue and malaria upon arrival in Spain via air travel.

METHODS

We have proposed a method to describe the regional distribution of imported cases of dengue and malaria based on the computation of the "travelers' index" from readily available socioeconomic data. We combined indicators representing the main drivers for international travel, including tourism, economy, and visits to friends and relatives, to measure the relative appeal of each region in the importing country for travelers. We validated the resulting estimates by comparing them with the reported cases of malaria and dengue in Spain from 2015 to 2019. We also assessed which motivation provided more accurate estimates for imported cases of both diseases.

RESULTS

The estimates provided by the best fitted model showed high correlation with notified cases of malaria (0.94) and dengue (0.87), with economic motivation being the most relevant for imported cases of malaria and visits to friends and relatives being the most relevant for imported cases of dengue.

CONCLUSIONS

Factual descriptions of the local movement of international travelers may substantially enhance the design of cost-effective prevention policies and control strategies, and essentially contribute to decision-support systems. Our approach contributes in this direction by providing a reliable estimate of the number of imported cases of nonendemic diseases, which could be generalized to other applications. Realistic risk assessments will be obtained by combining this regional predictor with the observed local distribution of vectors.

A Smartphone App for Real-Time Assessment of Malaria Prophylaxis Adverse Events

Background: Growth of international travel to malarial areas over the last decades has contributed to more travelers taking malaria prophylaxis. Travel-related symptoms may be wrongly attributed to malaria prophylaxis and hinder compliance. Here, we aimed to assess the frequency of real-time reporting of symptoms by travelers following malaria prophylaxis using a smartphone app. Method: Adult international travelers included in this single-center study (Barcelona, Spain) used the smartphone Trip Doctor® app developed by our group for real-time tracking of symptoms and adherence to prophylaxis. Results: Six hundred four (n = 604) international travelers were included in the study; 74.3% (449) used the app daily, and for one-quarter of travelers, malaria prophylaxis was prescribed. Participants from the prophylaxis group traveled more to Africa (86.7% vs. 4.3%; p < 0.01) and to high travel medical risk countries (60.8% vs. 18%; p < 0.01) and reported more immunosuppression (30.8% vs. 23.1% p < 0.01). Regarding symptoms, no significant intergroup differences were observed, and no relationship was found between the total number of malarial pills taken and reported symptoms. Conclusions: In our cohort, the number of symptoms due to malaria prophylaxis was not significantly higher than in participants for whom prophylaxis was not prescribed, and the overall proportion of symptoms is higher compared with other studies.

Infections diagnosed in children and young people screened for malaria in UK emergency departments: a retrospective multi-centre study

BACKGROUND

Data on imported infections in children and young people (CYP) are sparse.

AIMS

To describe imported infections in CYP arriving from malaria-endemic areas and presenting to UK emergency departments (ED) who were screened for malaria.

METHODS

This is a retrospective, multi-centre, observational study nested in a diagnostic accuracy study for malaria rapid diagnostic tests. Any CYP < 16 years presenting to a participating ED with a history of fever and travel to a malaria-endemic area between 1 January 2016 and 31 December 2017 and who had a malaria screen as a part of standard care were included. Geographical risk was calculated for the most common tropical infections.

RESULTS

Of the 1414 CYP screened for malaria, 44.0% (n = 622) arrived from South Asia and 33.3% (n = 471) from sub-Saharan Africa. Half (50.0%) had infections common in both tropical and non-tropical settings such as viral upper respiratory tract infection (URTI); 21.0% of infections were coded as tropical if gastro-enteritis is included, with a total of 4.2% (60) cases of malaria. CYP diagnosed with malaria were 7.44 times more likely to have arrived from sub-Saharan Africa than from South Asia (OR 7.44, 3.78-16.41).

CONCLUSION

A fifth of CYP presenting to participating UK EDs with fever and a history of travel to a malaria-endemic area and who were screened for malaria had a tropical infection if diarrhoea is included. A third of CYP had no diagnosis. CYP arriving from sub-Saharan Africa had the greatest risk of malaria.Abbreviations: CYP: children and young people; ED: emergency department; PERUKI: Paediatric Emergency Research in the UK and Ireland; RDT: rapid diagnostic test; VFR: visiting friends and relatives.

Imported malaria into Australia: surveillance insights and opportunities

BACKGROUND

Malaria continues to pose a significant burden in endemic countries, many of which lack access to molecular surveillance. Insights from malaria cases in travellers returning to non-endemic areas can provide valuable data to inform endemic country programmes. To evaluate the potential for novel global insights into malaria, we examined epidemiological and molecular data from imported malaria cases to Australia.

METHODS

We analysed malaria cases reported in Australia from 2012 to 2022 using National Notifiable Disease Surveillance System data. Molecular data on imported malaria cases were obtained from literature searches.

RESULTS

Between 2012 and 2022, 3204 malaria cases were reported in Australia. Most cases (69%) were male and 44% occurred in young adults aged 20-39 years. Incidence rates initially declined between 2012 and 2015, then increased until 2019. During 2012-2019, the incidence in travellers ranged from 1.34 to 7.71 per 100 000 trips. Cases were primarily acquired in Sub-Saharan Africa (n = 1433; 45%), Oceania (n = 569; 18%) and Southern and Central Asia (n = 367; 12%). The most common countries of acquisition were Papua New Guinea (n = 474) and India (n = 277). Plasmodium falciparum accounted for 58% (1871/3204) of cases and was predominantly acquired in Sub-Saharan Africa, and Plasmodium vivax accounted for 32% (1016/3204), predominantly from Oceania and Asia. Molecular studies of imported malaria cases to Australia identified genetic mutations and deletions associated with drug resistance and false-negative rapid diagnostic test results, and led to the establishment of reference genomes for P. vivax and Plasmodium malariae.

CONCLUSIONS

Our analysis highlights the continuing burden of imported malaria into Australia. Molecular studies have offered valuable insights into drug resistance and diagnostic limitations, and established reference genomes. Integrating molecular data into national surveillance systems could provide important infectious disease intelligence to optimize treatment guidelines for returning travellers and support endemic country surveillance programmes.

Malaria elimination in West Java, Indonesia: A descriptive-and-qualitative study

BACKGROUND OBJECTIVES

Following World Health Organization (WHO) plans for thirty-five malaria-endemic countries, Indonesia will eliminate malaria by 2030. As one of the Indonesian provinces, West Java targeted subnational malaria elimination in 2022. This article aims to describe malaria surveillance data and elimination programs, including weaknesses in sustaining the program.

METHODS

This study used secondary data from malaria surveillance information system regencies/cities' case reports for 2019-2022 and achievement data of sub-national malaria elimination certification from each regency/city from 2014-2022. The data was confirmed from the evaluation study document, analysis of reported cases, and interviews.

RESULTS

Most cases were confirmed by microscopic examination (84.1% in 2021 and 94.4% in 2022) and rapid diagnostic tests (57% in 2019 and 58.1% in 2020). Malaria is more prevalent among men (93% in 2019, 95% in 2020, 96% in 2021, and 95.9% in 2022) and productive ages of 15-64 years (98.8% in 2019, 100% in 2020, 99.2% in 2021, and 98.8% in 2022), frequently occurs in the military (56.3% in 2019, 75.7% in 2020, 45.2% in 2021) and police (40.5% in 2022), often uses passive case detection for identifying cases (97.9% in 2019 and 2020, 95.2% in 2021, and 97.6% in 2022), and the majority undergo inpatient treatment (86.4% in 2019, 81.7% in 2021, and 82.6% in 2022). Most positive cases originated from imported cases, and last indigenous cases were still found in 2019. Plasmodium vivax dominated malaria cases and and relapses were high (55.0% in 2020, and 47.3% in 2022).

INTERPRETATION CONCLUSION

All regencies/cities have obtained sub-national malaria elimination certification in 2022. West Java has the potential to be verified for Java-Bali sub-national malaria elimination targeted in 2023, albeit cases of imported malaria still occur. It is imperative to address the issue of imported cases transitioning into locally transmitted cases (introduced) by effective coordination across all regencies/cities and inter-provincial efforts.

Imported malaria: A 20-year retrospective study from a tertiary public hospital in Brussels, Belgium

BACKGROUND

Malaria continues to cause a significant number of infections in non-endemic regions. In this paper, we describe the epidemiological trend and morbidity of imported malaria diagnosed in a tertiary hospital in Brussels.

METHODS

We conducted a retrospective study describing a cohort of malaria episodes (in- and outpatients) at Centre Hospitalier Universitaire Saint-Pierre from 1998 to 2017. Epidemiological and clinical data were collected by reviewing medical files.

RESULTS

A total of 1011 malaria episodes were analyzed. Median age at diagnosis was 35 years, and 66 % of patients were men (672/1011). Malaria cases significantly increased over the two decades (from 17 in 1998 to 79 in 2017). Plasmodium falciparum malaria was most often diagnosed (846/935, 89 %), primarily from Central (530/935, 57 %) and West Africa (324/935, 35 %). Many cases (383/764, 50 %) were diagnosed in patients "visiting friends and relatives". HIV-infected and other immunocompromised patients were significantly more likely to present with severe malaria (at least one severity criteria as defined by the WHO) compared to other patients (24/57, 42 % vs 138/732, 19 %, p < 0.01 and 15/21, 71 % vs 147/767, 19 %, p < 0.001). Severe malaria was diagnosed in 16.9 % and the mortality rate was low (5/1011, 0.5 %).

CONCLUSION

Imported malaria increased over the years with a large, albeit stable number of cases diagnosed in patients visiting friends and relatives. These findings, along with the high rate of severe malaria in HIV and immunocompromised patients, underscore an urgent need for strengthened malaria surveillance and targeted preventive interventions.

Nine years of imported malaria in a teaching hospital in Belgium: Demographics, clinical characteristics, and outcomes

BACKGROUND

Imported malaria is often misdiagnosed due to the aspecific symptoms and lack of familiarity among clinicians. This study aims to evaluate a decade-long trend of imported malaria cases in a Belgian teaching hospital by analyzing demographics, clinical characteristics, and outcomes.

METHODS

Medical records of 223 patients with confirmed malaria diagnoses between 2010 and 2019 were analyzed.

RESULTS

Most patients were male (63.2%), aged 18-65 years (77.1%), and visiting friends or relatives (40.8%). Central Africa was the most common travel destination (54.3%), and 63.7% did not take prophylaxis. Symptoms were flu-like, with fever (91.9%) being most prevalent. P. falciparum was identified in 88.3% of cases. A high proportion of severe cases (41.7%) and a low mortality rate (0.9%) were recorded. A severe form of the disease is associated with a more extended hospital stay than uncomplicated form (median of 5 vs. 4 days, p < 0.001). Thirty-five-point five percent [33/93] of patients with severe malaria have had a previous malaria infection compared to 50.8% [66/130] of uncomplicated patients (p= 0.013) wich was statistically significant.

CONCLUSION

Malaria disproportionately affects VFRs traveling to Central Africa, and flu-like symptoms should raise suspicion. Prophylaxis is essential to prevent the disease, and early diagnosis is critical for effective management. A severe form of the disease is associated with a more extended hospital stay than uncomplicated form and people with a previous history of malaria have a less severe disease.

Length of stay in at-risk areas and time to malaria attack on return

BACKGROUND

Experimental infection with Plasmodium falciparum results in malaria attack within a few days of exposure. However, we have regularly observed malaria attack within a short time after return, regardless of the time spent in an endemic area. We therefore aimed to assess whether the time before return and malaria attack varies according to length of stay.

METHODS

We used anonymized data from the French National Reference Centre for Malaria between 2006 and 2016. We analyzed 11,823 cases aged at least 1 year and diagnosed with P. falciparum malaria 1 day to 1 year after returning to France, after a stay of 1 day to 1 year in an at-risk area.

RESULTS

Trips had a median duration of 31 days [IQR: 19-56]. Median time between return from the endemic area and onset of malaria symptoms was 5 days [IQR: 0-10], and the median between return and malaria diagnosis was 9 days [IQR: 5-14]. Times to symptom onset or diagnosis were longer for stays of fewer than 15 days vs 15 days or more (for symptoms: 7 vs 4 days for longer stays, for diagnosis: 11 vs 9 days). For stays longer than 15 days, no variation was observed according to length of stay.

CONCLUSIONS

Aside from at-risk stays of fewer than 15 days, the time between return and malaria attack is constant and rather short, even after long stays. The 2 weeks following return should be considered as a risk period whatever the length of stay in an at-risk area.

Evidence of malarial chemoprophylaxis among travellers who died from malaria: a systematic review and meta-analysis

BACKGROUND

Chemoprophylaxis is a prevention method for malaria during travel in malaria-endemic countries. This study aimed to collate and synthesize the evidence of malarial chemoprophylaxis among malaria death cases.

METHODS

Studies documenting malarial chemoprophylaxis related to malaria deaths were searched in PubMed, Scopus, MEDLINE, Embase, and CENTRAL until 3 July 2022. The pooled proportion of malarial chemoprophylaxis among death cases was synthesized using logit transformation and back transformation to a proportion performed using generalized linear mixed models. The pooled log odds ratio (log-OR) with a 95% confidence interval (CI) of malarial chemoprophylaxis in death cases compared to survivors were synthesized.

RESULTS

Fifty-eight studies were included in the systematic review and the meta-analysis. Of 602 pooled malaria death cases, the number of patients who took chemoprophylaxis was 187 (30%) (95% CI 22-40, P < 0.01, 58 studies), and those who took adequate chemoprophylaxis were 24 (5%) (95% CI 2-13, P < 0.01, 42 studies). A comparable log-OR of underwent chemoprophylaxis was observed between malaria death cases and survivors (P = 0.94, pooled log-OR: - 0.02, 95% CI - 0.46-0.42, I2: 0%, 17 studies). Similarly, a comparable log-OR of adequate chemoprophylaxis was identified between malaria death cases and survivors (P = 0.15, pooled log-OR: 0.83, 95% CI - 0.30-1.97, I2: 47.08%, 11 studies).

CONCLUSIONS

Among the studies where malarial chemoprophylaxis was reported, approximately 30% of malaria death cases had taken such prophylaxis. Notably, only 5% of these cases adhered fully or adequately to the recommended chemoprophylactic regimen. However, the analysis did not reveal a significant difference in the odds of malarial chemoprophylaxis between malaria death cases and survivors.

Malaria in Austria : A retrospective analysis of malaria cases diagnosed at a reference center in 2010-2020

BACKGROUND

Although malaria is not endemic to Austria, each year infections are imported by travellers, migrants and refugees. This study aims to provide an overview of malaria cases diagnosed at an Austrian institute for tropical medicine between 2010 and 2020.

METHODS

A retrospective, descriptive study was conducted based on the data of malaria cases confirmed at the Institute of Specific Prophylaxis and Tropical Medicine of the Medical University of Vienna. Laboratory diagnostics included microscopy, polymerase chain reaction (PCR) and real-time quantitative PCR.

RESULTS

Overall, 122 cases were identified. Annual case numbers were consistently higher from 2016 to 2020 than during the first half of the decade. Most malaria cases were diagnosed during summer and early autumn. This seasonal trend was not observed during the year 2020. With 55.1% (65/118) Plasmodium falciparum was the most common species, followed by Plasmodium vivax (19.5%, 23/118). The majority of patients were male (71.1%, 86/121) and the median age was 34.5 years (interquartile range, IQR 22.5-47.0 years). With a median age of 20.0 years (IQR 14.0-32.0 years), patients with P. vivax infections were younger than those infected with other Plasmodium species. Moreover, they were mostly male (82.6%, 19/23).

CONCLUSION

From 2010 to 2020, the number of malaria cases diagnosed at the center increased. Growing international mobility and changing travel behavior could at least partly be responsible for this trend and there are indications that particularly P. vivax infections were imported by migrants and refugees.

Bayesian belief network modelling approach for predicting and ranking risk factors for malaria infections among children under 5 years in refugee settlements in Uganda

BACKGROUND

Malaria risk factors at household level are known to be complex, uncertain, stochastic, nonlinear, and multidimensional. The interplay among these factors, makes targeted interventions, and resource allocation for malaria control challenging. However, few studies have demonstrated malaria's transmission complexity, control, and integrated modelling, with no available evidence on Uganda's refugee settlements. Using the 2018-2019 Uganda's Malaria Indicator Survey (UMIS) data, an alternative Bayesian belief network (BBN) modelling approach was used to analyse, predict, rank and illustrate the conceptual reasoning, and complex causal relationships among the risk factors for malaria infections among children under-five in refugee settlements of Uganda.

METHODS

In the UMIS, household level information was obtained using standardized questionnaires, and a total of 675 children under 5 years were tested for malaria. From the dataset, a casefile containing malaria test results, demographic, social-economic and environmental information was created. The casefile was divided into a training (80%, n = 540) and testing (20%, n = 135) datasets. The training dataset was used to develop the BBN model following well established guidelines. The testing dataset was used to evaluate model performance.

RESULTS

Model accuracy was 91.11% with an area under the receiver-operating characteristic curve of 0.95. The model's spherical payoff was 0.91, with the logarithmic, and quadratic losses of 0.36, and 0.16 respectively, indicating a strong predictive, and classification ability of the model. The probability of refugee children testing positive, and negative for malaria was 48.1% and 51.9% respectively. The top ranked malaria risk factors based on the sensitivity analysis included: (1) age of child; (2) roof materials (i.e., thatch roofs); (3) wall materials (i.e., poles with mud and thatch walls); (4) whether children sleep under insecticide-treated nets; 5) type of toilet facility used (i.e., no toilet facility, and pit latrines with slabs); (6) walk time distance to water sources (between 0 and 10 min); (7) drinking water sources (i.e., open water sources, and piped water on premises).

CONCLUSION

Ranking, rather than the statistical significance of the malaria risk factors, is crucial as an approach to applied research, as it helps stakeholders determine how to allocate resources for targeted malaria interventions within the constraints of limited funding in the refugee settlements.

An old foe on peculiar paths: severe falciparum malaria in a Syrian refugee, possibly infected during migrant smuggling from Türkiye to Germany

Infectious diseases and their imperative awareness gain major relevance through global warming and multi-continent refugee crises. Here, we demonstrate the challenges of malaria diagnosis, disease course, and treatment, including post-artesunate hemolysis in a Syrian refugee with severe falciparum malaria, most probably infected during migrant smuggling from Türkiye to Germany.

A malaria death due to an imported Plasmodium falciparum infection in Sri Lanka during the prevention of re-establishment phase of malaria

BACKGROUND

Sri Lanka has maintained a rigorous programme to prevent the re-establishment of malaria ever since the disease was eliminated in October 2012. It includes efforts to sustain case surveillance to ensure early diagnosis and management of malaria. Yet, in April of 2023 the death occurred of an individual with imported malaria.

CASE PRESENTATION

The deceased was a 37-year-old Sri Lankan male who returned to Sri Lanka on the 10th of April after a business trip to several countries including Tanzania. He was febrile on arrival and consulted three Allopathic Medical Practitioners in succession in his home town in the Western Province of Sri Lanka, over a period of 5 days starting from the very day that he arrived in the country. Malaria was not tested for at any of these consultations and his clinical condition deteriorated. On the evening of 14th of April he was admitted to the medical intensive care unit of a major private hospital in the capital city of Colombo with multiple organ failure. There, on a request by the treating physician blood was tested for malaria and reported early the next morning as Plasmodium falciparum malaria with a high parasitaemia (> 10%). The patient died shortly after on the 15th of April before any anti-malarial medication was administered. The deceased had been a frequent business traveller to Africa, but with no past history of malaria. He had not taken chemoprophylaxis for malaria on this or previous travels to Africa.

DISCUSSION

The patient's P. falciparum infection progressed rapidly over 5 days of arriving in Sri Lanka leading to severe malaria without being diagnosed, despite him seeking healthcare from three different Medical Practitioners. Finally, a diagnosis of malaria was made on admission to an intensive care unit; the patient died before anti-malarial medicines were administered.

CONCLUSIONS

This first death due to severe P. falciparum malaria reported in Sri Lanka after elimination of the disease was due to the delay in diagnosing malaria.

Updates on Malaria Epidemiology and Prevention Strategies

Purpose of Review

The objective of this review was to provide an update on recent malaria epidemiology, both globally and in non-endemic areas, to identify the current distribution and repercussions of genetically diverse Plasmodium species and summarize recently implemented intervention and prevention tools.

Recent Findings

Notable changes in malaria epidemiology have occurred in recent years, with an increase in the number of total cases and deaths globally during 2020-2021, in part attributed to the COVID-19 pandemic. The emergence of artemisinin-resistant species in new areas and the expanding distribution of parasites harbouring deletions of the pfhrp2/3 genes have been concerning. New strategies to curb the burden of this infection, such as vaccination, have been implemented in certain endemic areas and their performance is currently being evaluated.

Summary

Inadequate control of malaria in endemic regions may have an effect on imported malaria and measures to prevent re-establishment of transmission in malaria-free areas are essential. Enhanced surveillance and investigation of Plasmodium spp. genetic variations will contribute to the successful diagnosis and treatment of malaria in future. Novel strategies for an integrated One Health approach to malaria control should also be strengthened.

Determinants of malaria infections among children in refugee settlements in Uganda during 2018-2019

BACKGROUND

While 5% of 247 million global malaria cases are reported in Uganda, it is also a top refugee hosting country in Africa, with over 1.36 million refugees. Despite malaria being an emerging challenge for humanitarian response in refugee settlements, little is known about its risk factors. This study aimed to investigate the risk factors for malaria infections among children under 5 years of age in refugee settlements in Uganda.

METHODS

We utilized data from Uganda's Malaria Indicator Survey which was conducted between December 2018 and February 2019 at the peak of malaria season. In this national survey, household level information was obtained using standardized questionnaires and a total of 7787 children under 5 years of age were tested for malaria using mainly the rapid diagnostic test. We focused on 675 malaria tested children under five in refugee settlements located in Yumbe, Arua, Adjumani, Moyo, Lamwo, Kiryadongo, Kyegegwa, Kamwenge and Isingiro districts. The extracted variables included prevalence of malaria, demographic, social-economic and environmental information. Multivariable logistic regression was used to identify and define the malaria associated risk factors.

RESULTS

Overall, malaria prevalence in all refugee settlements across the nine hosting districts was 36.6%. Malaria infections were higher in refugee settlements located in Isingiro (98.7%), Kyegegwa (58.6%) and Arua (57.4%) districts. Several risk factors were significantly associated with acquisition of malaria including fetching water from open water sources [adjusted odds ratio (aOR) = 1.22, 95% CI: 0.08-0.59, P = 0.002], boreholes (aOR = 2.11, 95% CI: 0.91-4.89, P = 0.018) and water tanks (aOR = 4.47, 95% CI: 1.67-11.9, P = 0.002). Other factors included pit-latrines (aOR = 1.48, 95% CI: 1.03-2.13, P = 0.033), open defecation (aOR = 3.29, 95% CI: 1.54-7.05, P = 0.002), lack of insecticide treated bed nets (aOR = 1.15, 95% CI: 0.43-3.13, P = 0.003) and knowledge on the causes of malaria (aOR = 1.09, 95% CI: 0.79-1.51, P = 0.005).

CONCLUSIONS

The persistence of the malaria infections were mainly due to open water sources, poor hygiene, and lack of preventive measures that enhanced mosquito survival and infection. Malaria elimination in refugee settlements requires an integrated control approach that combines environmental management with other complementary measures like insecticide treated bed nets, indoor residual spraying and awareness.

Quinoline-based heterocyclic hydrazones: Design, synthesis, anti-plasmodial assessment, and mechanistic insights

A library of quinoline-based hydrazones bearing 1H-1,2,3-triazole core was designed, synthesized, and evaluated for their antiplasmodial activity against the drug-resistant Plasmodium falciparum W2 strain. The inclusion of pyrazine-2-carboxylic acid with a flexible propyl spacer afforded the most active scaffold with an IC₅₀ value of 0.26 μM. Mechanistically, the compound inhibited heme to hemozoin formation, as demonstrated by UV-vis and mass spectral studies.

Malaria Detection Using Advanced Deep Learning Architecture

Malaria is a life-threatening disease caused by parasites that are transmitted to humans through the bites of infected mosquitoes. The early diagnosis and treatment of malaria are crucial for reducing morbidity and mortality rates, particularly in developing countries where the disease is prevalent. In this article, we present a novel convolutional neural network (CNN) architecture for detecting malaria from blood samples with a 99.68% accuracy. Our method outperforms the existing approaches in terms of both accuracy and speed, making it a promising tool for malaria diagnosis in resource-limited settings. The CNN was trained on a large dataset of blood smears and was able to accurately classify infected and uninfected samples with high sensitivity and specificity. Additionally, we present an analysis of model performance on different subtypes of malaria and discuss the implications of our findings for the use of deep learning in infectious disease diagnosis.

Questionnaire-Based Analysis of Adverse Events and Compliance with Malaria Chemoprophylaxis in Taiwan

Malaria was eradicated in Taiwan in 1952; however, imported malaria cases are reported every year. The subtropical climate in Taiwan permits mosquito propagation and possible outbreaks of mosquito-borne diseases. The aim of this study was to investigate travelers' compliance and side effects of malaria prophylaxis to prevent a malaria outbreak in Taiwan. In this prospective study, we enrolled travelers who visited our travel clinic before going to malarious areas. A total of 161 questionnaires were collected and analyzed. Associations between the occurrence of side effects and compliance with antimalarial drugs were analyzed. Adjusted odds ratios were calculated after adjusting for potential risk factors in multiple logistic regression analysis. Of the 161 enrolled travelers, 58 (36.0%) reported side effects. Insomnia, somnolence, irritability, nausea, and anorexia were associated with poor compliance. Mefloquine was not associated with more neuropsychological side effects than doxycycline. Multiple logistic regression analysis showed that chemoprophylaxis compliance was affected by a younger age, visiting friends and relatives, visiting the travel clinic more than 1 week before the trip, and preferring to use the same antimalarial regimen on the next trip. Our findings could provide information to travelers besides labeled side effects to improve compliance with malaria prophylaxis and consequently help to prevent malaria outbreaks in Taiwan.

Malaria parasite prevalence in Sub-Saharan African migrants screened in Sweden: a cross-sectional study

Background

Asymptomatic infections with malaria parasites are common in populations in endemic areas. These infections may persist in migrants after arrival in a non-endemic area. Screening to find and clear these infections is generally not implemented in non-endemic countries, despite a potential negative health impact. We performed a study to evaluate the Plasmodium parasite prevalence in migrants living in Sweden.

Methods

Adults and children born in Sub-Saharan Africa (SSA) were invited in the study between April 2019 and June 2022 at 10 different sites, mainly as part of the national Migrant Health Assessment Program in Stockholm and Västerås, Sweden. Rapid diagnostic tests (RDT) and real-time PCR were used to detect malaria parasites. Prevalence and test sensitivity were calculated with 95% confidence intervals (CI). Univariate and multivariable logistic regression were used to evaluate associations with PCR positivity.

Findings

In total, 789 individuals were screened for Plasmodium spp. of which 71 (9.0%) were positive by PCR and 18 (2.3%) also by RDT. When performed during the national screening program, 10.4% was PCR positive. A high prevalence was detected in migrants with Uganda as the country of last residence, 53/187 (28.3%), and in this group the prevalence was highest in children, 29/81 (35.8%). Among the PCR positive, 47/71 (66.2%) belonged to families with at least one other member testing positive (odds ratio [OR] 43.4 (95% CI 19.0-98.9), and the time lived in Sweden ranged between 6 and 386 days.

Interpretation

A high malaria parasite prevalence was found in migrants from SSA, particularly in children offered screening in Stockholm, Sweden during the study period. Awareness of asymptomatic malaria infection is needed and screening for malaria in migrants arriving from high endemic countries should be considered.

Funding

The Swedish Research Council, Stockholm County Council and Centre for Clinical Research, Västmanland, Sweden.

Analysis of epidemiological changes and elimination effects for malaria in Handan city, the north China

The elimination of malaria requires high-quality surveillance data to quickly detect and respond to individual cases. This study aims to analyze the epidemiological characteristics of malaria and ascertain the long-term epidemic trends of malaria by 2020 in Handan China. Case-level data for the period 2011 to 2020 were extracted from Chinese Information System for Disease Control and Prevention. The lamp trap method was used to capture mosquitoes so that the characteristics of mosquitoes can be analyzed. The incidence, accuracy, and timeliness of malaria case diagnosis, reporting and investigation were evaluated at the elimination stage (2011-2020) in Handan City, China. Between 2011 and 2020, 94 malaria cases were reported in Handan City, of which 93 malaria cases were male and all of which were imported from abroad. The annual average incidence decreased from 622.33/100,000 to 0.11/100,000 in the elimination stage. Since the initiation of the National Malaria Elimination Program in 2010, malaria cases have been consistent with the increase in overseas export channels and labor personnel service. There is a need to strengthen malaria surveillance of returning workers from Africa and to conduct timely blood tests to diagnose and treat imported infections. Local authorities ensure that imported malaria cases can be timely diagnosed, reported, treated and investigated at local level.

Modeling malaria transmission in Nepal: impact of imported cases through cross-border mobility

The cross-border mobility of malaria cases poses an obstacle to malaria elimination programmes in many countries, including Nepal. Here, we develop a novel mathematical model to study how the imported malaria cases through the Nepal-India open-border affect the Nepal government's goal of eliminating malaria by 2026. Mathematical analyses and numerical simulations of our model, validated by malaria case data from Nepal, indicate that eliminating malaria from Nepal is possible if strategies promoting the absence of cross-border mobility, complete protection of transmission abroad, or strict border screening and isolation are implemented. For each strategy, we establish the conditions for the elimination of malaria. We further use our model to identify the control strategies that can help maintain a low endemic level. Our results show that the ideal control strategies should be designed according to the average mosquito biting rates that may depend on the location and season.

The imported infections among foreign travelers in China: an observational study

BACKGROUND

In the past few decades, globalization has rendered more frequent and intensive population movement between countries, which has changed the original disease spectrum and brought a huge health impact on the global population including China. This study aims to describe the spectrum and epidemiological characteristics of imported infections among foreign travelers travelling to China.

METHODS

The data on imported infections among foreign travelers were obtained from Custom Inbound Screening System (CISS) and the National Notifiable Infectious Disease Reporting System (NNIDRS). All the infections were classified into respiratory, gastrointestinal, vector-borne, blood/sex-transmitted and mucocutaneous diseases, of which case numbers and incidences were calculated and the proportions were compared among subgroups.

RESULTS

In total, 17,189 travelers diagnosed with 58 imported infectious diseases were reported from 2014 to 2018, with an overall incidence of 122.59 per million. Respiratory infection (7,351 cases, mainly influenza) and blood/sex-transmitted diseases (6,114 cases mainly Hepatitis B and HIV infection) were the most frequently diagnosed diseases, followed by vector-borne infections (3,128 cases, mainly dengue fever and malaria). The highest case number was from Asia and Europe, while the highest incidence rate was from Africa (296.00 per million). When specific diagnosis was compared, both the highest absolute case number and incidence were observed for influenza. An obvious seasonal pattern was observed for vector-borne diseases, with the annual epidemic spanning from July to November. The origin-destination matrices disclosed the movement of imported infection followed specific routes.

CONCLUSIONS

Our study provided a profile of infectious diseases among foreign travelers travelling to China and pinpointed the target regions, seasons and populations for prevention and control, to attain an informed control of imported infections in China.

The Emergence of Travel-related Infections in Critical Care Units

Several tropical or geographically confined infectious diseases may lead to organ failure requiring management in an intensive care unit (ICU), both in endemic low- and middle-income countries where ICU facilities are increasingly being developed and in (nonendemic) high-income countries through an increase in international travel and migration. The ICU physician must know which of these diseases may be encountered and how to recognize, differentiate, and treat them. The four historically most prevalent "tropical" diseases (malaria, enteric fever, dengue, and rickettsiosis) can present with single or multiple organ failure in a very similar manner, which makes differentiation based solely on clinical signs very difficult. Specific but frequently subtle symptoms should be considered and related to the travel history of the patient, the geographic distribution of these diseases, and the incubation period. In the future, ICU physicians may also be more frequently confronted with rare but frequently lethal diseases, such as Ebola and other viral hemorrhagic fevers, leptospirosis, and yellow fever. No one could have foreseen the worldwide 2019-up to now coronavirus disease 2019 (COVID-19) crisis caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which was initially spread by travel too. In addition, the actual pandemic due to SARS-CoV-2 reminds us of the actual and potential threat of (re)-emerging pathogens. If left untreated or when treated with a delay, many travel-related diseases remain an important cause of morbidity and even mortality, even when high-quality critical care is provided. Awareness and a high index of suspicion of these diseases is a key skill for the ICU physicians of today and tomorrow to develop.

Imported malaria definition and minimum data for surveillance

The mobility of malaria-infected individuals poses challenges to elimination campaigns by way of spreading parasite drug resistance, straining country-to-country collaboration, and making routine data collection difficult, especially in resource-poor settings. Nevertheless, no concerted effort has been made to develop a common framework to define the spatial and temporal components of an imported malaria case and recommend the minimum data needed to identify it. We conducted a scoping review of imported malaria literature from 2010 to 2020 which showed that definitions vary widely, and local capabilities of detecting importation are often restricted in low-income countries. Following this, we propose a common definition for imported malaria and the minimum data required to identify a case, depending on the country's capability of conducting an epidemiological investigation. Lastly, we utilize the proposed definition using data from Brazil to demonstrate both the feasibility and the importance of tracking imported cases. The case of Brazil highlights the capabilities of regular surveillance systems to monitor importation, but also the need to regularly use these data for informing local responses. Supporting countries to use regularly collected data and adopt a common definition is paramount to tackling the importation of malaria cases and achieving elimination goals set forth by the World Health Organization.

Trends in imported malaria during the COVID-19 pandemic, Spain (+Redivi Collaborative Network)

INTRODUCTION

The COVID-19 pandemic has caused disruptions in prevention and management strategies for malaria globally. Currently, data analysing trends in travel-related infections during the pandemic years are scarce. The objective of this analysis was to describe the epidemiological and clinical characteristics of patients with imported malaria within the +Redivi network in Spain, focusing on yearly trends from pre-pandemic years to date.

METHODS

Cases recorded in +Redivi from October 2009 to December 2021 were analysed and patients with a diagnosis of malaria (standard diagnostic methods using thick/thin peripheral blood smears, with/without a malaria rapid diagnostic test and/or Plasmodium spp. polymerase chain reaction) were identified. The total number of malaria cases, cases according to type of patient and severe cases, per year, were analysed.

RESULTS

In total, 1751 cases of malaria (1751/26 601, 6.6%) were identified. The majority occurred in males (1041, 59.5%), median age was 36.3 (interquartile range: 27-44.7) years and most occurred in visiting friends and relatives (VFR)-immigrants (872, 49.8%). Most infections were acquired in sub-Saharan Africa (1.660, 94.8%) and were due to Plasmodium falciparum (81.3%). There were 64 cases of severe malaria (3.7%) and 4 patients died (0.2% mortality, all in pre-pandemic years). A significant increase in cases of severe malaria was observed during the study period (P < 0.001) (attributable to the increase in 2021). There were 16/93 severe cases in 2021 (17.2%), all due to Plasmodium falciparum, (compared with ≤ 5% in previous years), which mainly occurred in travellers and VFR-immigrants (10/16, 62.5% and 5/16, 31.3%, respectively).

CONCLUSIONS

After an initial decline associated with travel restrictions due to the ongoing COVID-19 pandemic, an increase in imported malaria and a significant increase in cases of severe malaria was observed. Patients with imported malaria may present and/or be diagnosed late during this public health crisis and health care professionals should be alerted to the recent increase in severe cases.

Malaria Surveillance — United States, 2018

Problem/Condition

Malaria in humans is caused by intraerythrocytic protozoa of the genus Plasmodium. These parasites are transmitted by the bite of an infective female Anopheles species mosquito. Most malaria infections in the United States and its territories occur among persons who have traveled to regions with ongoing malaria transmission. However, among persons who have not traveled out of the country, malaria is occasionally acquired through exposure to infected blood or tissues, congenital transmission, nosocomial exposure, or local mosquitoborne transmission. Malaria surveillance in the United States and its territories provides information on its occurrence (e.g., temporal, geographic, and demographic), guides prevention and treatment recommendations for travelers and patients, and facilitates rapid transmission control measures if locally acquired cases are identified.

Period Covered

This report summarizes confirmed malaria cases in persons with onset of illness in 2018 and trends in previous years.

Description of System

Malaria cases diagnosed by blood smear microscopy, polymerase chain reaction, or rapid diagnostic tests are reported to local and state health departments through electronic laboratory reports or by health care providers or laboratory staff members directly reporting to CDC or health departments. Case investigations are conducted by local and state health departments, and reports are transmitted to CDC through the National Malaria Surveillance System (NMSS), the National Notifiable Diseases Surveillance System (NNDSS), or direct CDC clinical consultations. CDC reference laboratories provide diagnostic assistance and conduct antimalarial drug resistance marker testing on blood specimens submitted by health care providers or local or state health departments. This report summarizes data from the integration of all cases from NMSS and NNDSS, CDC clinical consultations, and CDC reference laboratory reports.

Results

CDC received reports of 1,823 confirmed malaria cases with onset of symptoms in 2018, including one cryptic case and one case acquired through a bone marrow transplant. The number of cases reported in 2018 is 15.6% fewer than in 2017. The number of cases diagnosed in the United States and its territories has been increasing since the mid-1970s; the number of cases reported in 2017 was the highest since 1972. Of the cases in 2018, a total of 1,519 (85.0%) were imported cases that originated from Africa; 1,061 (69.9%) of the cases from Africa were from West Africa, a similar proportion to what was observed in 2017. Among all cases, P. falciparum accounted for most infections (1,273 [69.8%]), followed by P. vivax (173 [9.5%]), P. ovale (95 [5.2%]), and P. malariae (48 [2.6%]). For the first time since 2008, an imported case of P. knowlesi was identified in the United States and its territories. Infections by two or more species accounted for 17 cases (<1.0%). The infecting species was not reported or was undetermined in 216 cases (11.9%). Most patients (92.6%) had symptom onset <90 days after returning to the United States or its territories from a country with malaria transmission. Of the U.S. civilian patients who reported reason for travel, 77.0% were visiting friends and relatives. Chemoprophylaxis with antimalarial medications are recommended for U.S. residents to prevent malaria while traveling in countries where it is endemic. Fewer U.S. residents with imported malaria reported taking any malaria chemoprophylaxis in 2018 (24.5%) than in 2017 (28.4%), and adherence was poor among those who took chemoprophylaxis. Among the 864 U.S. residents with malaria for whom information on chemoprophylaxis use and travel region were known, 95.0% did not adhere to or did not take a CDC-recommended chemoprophylaxis regimen. Among 683 women with malaria, 19 reported being pregnant. Of these, 11 pregnant women were U.S. residents, and one of whom reported taking chemoprophylaxis to prevent malaria but her adherence to chemoprophylaxis was not reported. Thirty-eight (2.1%) malaria cases occurred among U.S. military personnel in 2018, more than in 2017 (26 [1.2%]). Among all reported malaria cases in 2018, a total of 251 (13.8%) were classified as severe malaria illness, and seven persons died from malaria. In 2018, CDC analyzed 106 P. falciparum-positive and four P. falciparum mixed species specimens for antimalarial resistance markers (although certain loci were untestable in some specimens); identification of genetic polymorphisms associated with resistance to pyrimethamine were found in 99 (98.0%), to sulfadoxine in 49 (49.6%), to chloroquine in 50 (45.5%), and to mefloquine in two (2.0%); no specimens tested contained a marker for atovaquone or artemisinin resistance.

Interpretation

The importation of malaria reflects the overall trends in global travel to and from areas where malaria is endemic, and 15.6% fewer cases were imported in 2018 compared with 2017. Of imported cases, 59.3% were among persons who had traveled from West Africa. Among U.S. civilians, visiting friends and relatives was the most common reason for travel (77.1%).

Public Health Actions

The best way for U.S. residents to prevent malaria is to take chemoprophylaxis medication before, during, and after travel to a country where malaria is endemic. Adherence to recommended malaria prevention strategies among U.S. travelers would reduce the number of imported cases. Reported reasons for nonadherence include prematurely stopping after leaving the area where malaria was endemic, forgetting to take the medication, and experiencing a side effect. Health care providers can make travelers aware of the risks posed by malaria and incorporate education to motivate them to be adherent to chemoprophylaxis. Malaria infections can be fatal if not diagnosed and treated promptly with antimalarial medications appropriate for the patient’s age, pregnancy status, medical history, the likely country of malaria acquisition, and previous use of antimalarial chemoprophylaxis. Antimalarial use for chemoprophylaxis and treatment should be determined by the CDC guidelines, which are frequently updated. In April 2019, intravenous (IV) artesunate became the first-line medication for treatment of severe malaria in the United States and its territories. Artesunate was approved by the Food and Drug Administration (FDA) in 2020 and is commercially available (Artesunate for Injection) from major U.S. drug distributors (https://amivas.com). Stocking IV artesunate locally allows for immediate treatment of severe malaria once diagnosed and provides patients with the best chance of a complete recovery and no sequelae. With commercial IV artesunate now available, CDC will discontinue distribution of non–FDA-approved IV artesunate under an investigational new drug protocol on September 30, 2022. Detailed recommendations for preventing malaria are online at https://www.cdc.gov/malaria/travelers/drugs.html. Malaria diagnosis and treatment recommendations are also available online at https://www.cdc.gov/malaria/diagnosis_treatment. Health care providers who have sought urgent infectious disease consultation and require additional assistance on diagnosis and treatment of malaria can call the Malaria Hotline 9:00 a.m.–5:00 p.m. Eastern Time, Monday–Friday, at 770-488-7788 or 855-856-4713 or after hours for urgent inquiries at 770-488-7100. Persons submitting malaria case reports (care providers, laboratories, and state and local public health officials) should provide complete information because incomplete reporting compromises case investigations and public health efforts to prevent future infections and examine trends in malaria cases. Molecular surveillance of antimalarial drug resistance markers enables CDC to track, guide treatment, and manage drug resistance in malaria parasites both domestically and globally. A greater proportion of specimens from domestic malaria cases are needed to improve the completeness of antimalarial drug resistance analysis; therefore, CDC requests that blood specimens be submitted for any case of malaria diagnosed in the United States and its territories.

Prevalence, anti-malarial chemoprophylaxis and causes of deaths for severe imported malaria: A systematic review and meta-analysis

BACKGROUND

There are limited data regarding prevalence, anti-malarial chemoprophylaxis, and causes of death for severe imported malaria. Thus, we conducted a systematic review and meta-analysis to characterise these variables.

METHODS

We searched studies reporting deaths attributable to severe imported malaria. The following pooled prevalence rates were determined: 1) the pooled prevalence of severe malaria among patients with imported malaria, 2) the pooled prevalence of deaths among patients with severe imported malaria, 3) the pooled prevalence of anti-malarial chemoprophylaxis among patients with severe imported malaria, and 4) the causes of death among patients with severe imported malaria.

RESULTS

The search identified 52 studies that were mainly conducted in Europe (25, 48.1%), North America (16, 30.8%) and Asia (7, 13.5%). The pooled prevalence of severe imported malaria was 12.5% (95% confidence interval [CI] = 10.3%-14.6%, I² = 99.32%, 12393 severe cases/118325 imported cases). The pooled prevalence of deaths attributable to severe imported malaria was 5.1% (95% CI = 4.0%-6.2%, I² = 91.72%, 721 deaths/16310 severe cases). The pooled prevalence of adequate anti-malarial chemoprophylaxis among patients with severe imported malaria was 9.7% (95% CI = 6.5%-13.0%, I² = 89.9%, 203/2049 cases). The most common cause of death was multi-organ failure (12.3%).

CONCLUSION

The results highlighted the need for education and preventative measures for travellers, immigrants, or workers who plan to visit malaria-endemic areas to minimize the risk of severe disease or death.

A PfSPZ vaccine immunization regimen equally protective against homologous and heterologous controlled human malaria infection

Immunization with radiation-attenuated Plasmodium falciparum (Pf) sporozoites (SPZ) in PfSPZ Vaccine, has provided better vaccine efficacy (VE) against controlled human malaria infection (CHMI) with the same parasites as in the vaccine (homologous) than with genetically distant parasites (heterologous). We sought to identify an immunization regimen that provided similar VE against CHMI with homologous and heterologous Pf for at least 9 weeks in malaria-naïve adults. Such a regimen was identified in part 1 (optimization), an open label study, and confirmed in part 2 (verification), a randomized, double-blind, placebo-controlled study in which VE was assessed by cross-over repeat CHMI with homologous (PfNF54) and heterologous (Pf7G8) PfSPZ at 3 and 9–10 weeks. VE was calculated using Bayesian generalized linear regression. In part 1, vaccination with 9 × 10⁵ PfSPZ on days 1, 8, and 29 protected 5/5 (100%) subjects against homologous CHMI at 3 weeks after the last immunization. In part 2, the same 3-dose regimen protected 5/6 subjects (83%) against heterologous CHMI at both 3 and 9–10 weeks after the last immunization. Overall VE was 78% (95% predictive interval: 57–92%), and against heterologous and homologous was 79% (95% PI: 54–95%) and 77% (95% PI: 50–95%) respectively. PfSPZ Vaccine was safe and well tolerated. A 4-week, 3-dose regimen of PfSPZ Vaccine provided similar VE for 9–10 weeks against homologous and heterologous CHMI. The trial is registered with ClinicalTrials.gov, NCT02704533.

Spatial Analysis of Mosquito-Borne Diseases in Europe: A Scoping Review

Mosquito-borne infections are increasing in endemic areas and previously unaffected regions. In 2020, the notification rate for Dengue was 0.5 cases per 100,000 population, and for Chikungunya <0.1/100,000. In 2019, the rate for Malaria was 1.3/100,000, and for West Nile Virus, 0.1/100,000. Spatial analysis is increasingly used in surveillance and epidemiological investigation, but reviews about their use in this research topic are scarce. We identify and describe the methodological approaches used to investigate the distribution and ecological determinants of mosquito-borne infections in Europe. Relevant literature was extracted from PubMed, Scopus, and Web of Science from inception until October 2021 and analysed according to PRISMA-ScR protocol. We identified 110 studies. Most used geographical correlation analysis (n = 50), mainly applying generalised linear models, and the remaining used spatial cluster detection (n = 30) and disease mapping (n = 30), mainly conducted using frequentist approaches. The most studied infections were Dengue (n = 32), Malaria (n = 26), Chikungunya (n = 26), and West Nile Virus (n = 24), and the most studied ecological determinants were temperature (n = 39), precipitation (n = 24), water bodies (n = 14), and vegetation (n = 11). Results from this review may support public health programs for mosquito-borne disease prevention and may help guide future research, as we recommended various good practices for spatial epidemiological studies.

Survey and Analysis of Chemoprophylaxis Policies for Domestic Travel in Malaria-Endemic Countries

The prevention of malaria in travelers with the use of antimalarials often occurs in connection with international travel to areas of significant risk of infection. Although these travelers sometimes cause outbreaks in their malaria-free home countries, the cardinal objective of prescribed chemoprophylaxis is to protect the traveler from patent malaria during travel. Here we consider the chemoprophylaxis of domestic travelers from malaria-free but -receptive areas within malaria-endemic countries. The main objective in this setting is the protection of those areas from reintroduced malaria transmission. In order to better understand policy and practices in this regard, we surveyed malaria prevention and treatment guidelines of 36 malaria-endemic countries and 2 that have recently eliminated malaria (Sri Lanka, China) for recommendations regarding malaria chemoprophylaxis for domestic travel. Among them, just 8 provided specific and positive recommendations, 1 recommended without specific guidance, and 4 advised against the practice. Most nations (25/38; 66%) did not mention chemoprophylaxis for domestic travel, though many of those did offer guidance for international travel. The few positive recommendations for domestic travel were dominated by the suppressive prophylaxis options of daily doxycycline or atovaquone-proguanil or weekly mefloquine. The incomplete protection afforded by these strategies, along with impractical dosing in connection with the typically brief domestic travel, may in part explain the broad lack of policies and practices across malaria-endemic nations regarding chemoprophylaxis.

Gaps in knowledge and practices of malaria prevention in Francophone African immigrants in Metropolitan Edmonton

Background

Important knowledge gaps exist in the understanding of the management of the risks of imported malaria in Canada among Francophone immigrants from sub-Saharan Africa (FISSA). The aim of this cross-sectional study was to investigate the malaria related-knowledge, attitude and practices (KAP) of FISSA in Edmonton, where these immigrants are in an official minority language situation and the impact of language barriers on these factors.

Methods

A structured survey was used to examine the KAP of 382 FISSA in the Edmonton area from 2018 to 2019. Fisher’s Exact Test was applied to determine if there were associations between knowledge of malaria and different risk factors.

Results

Almost all FISSA (97%) had an accurate knowledge of fever as the key symptom of malaria. Interestingly, 60% of participants identified bed nets as a preventive method and only 19% of participants had accurate knowledge of malaria transmission. An accurate knowledge of symptoms was significantly associated with a high perceived risk of contracting malaria [odds ratio (OR) 4.33, 95% confidence interval (CI) 1.07–20.62]. Furthermore, even though 70% of FISSA had a high perceived risk of contracting malaria in endemic regions, only 52% of travellers had a pre-travel medical encounter. Importantly, language was not the predominant reason for not seeking pre-travel medical advice, although 84% of respondents chose French as their official language of preference when seeking medical advice. Having a French-speaking physician was correlated with satisfactory prevention knowledge (OR 1.96, 95% CI 1.16–3.35). With respect to health-seeking behaviour, 88% of respondents with a child < 5 years of age would seek medical care for fever in the child after travel to sub-Saharan Africa (SSA).

Conclusion

This study highlights that factors other than knowledge, risk assessment, and language might determine the lack of compliance with pre-travel medical encounters. It underscores the need for effective strategies to improve this adherence in minority settings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-022-04210-w.

High asymptomatic malaria among seasonal migrant workers departing to home from malaria endemic areas in northwest Ethiopia

Background

In Ethiopia, thousands of seasonal migrant workers travel from non-malaria or mild malaria transmission areas to malaria-endemic areas for seasonal farm activities. Most of these migrants stay in the farm areas for land preparation, plowing, planting, weeding, and harvesting for a specific period and return to their living areas. However, there is limited evidence of how seasonal migrant workers contribute to the transmission of malaria to new or less malaria transmission areas.

Methods

A cross-sectional study was conducted at the departure phase of seasonal migrant workers in the Metema district from September 2018 to October 2019. A total of 1208 seasonal migrant workers were interviewed during their departure from farm sites to their homes. The face-to-face interviews were performed using a pretested structured questionnaire. Moreover, blood samples were collected from each study participant for microscopic malaria parasite examination. The data were fitted with the logistic regression model to estimate the predictors of malaria transmission.

Results

At departure to home, the prevalence of malaria among seasonal migrant workers was 17.5% (15.6–19.45%). Approximately 71.80% (177/212) of the cases were Plasmodium falciparum, and 28.20% (35/212) were Plasmodium vivax. Most seasonal migrant workers 934 (77.4%) were from rural residences and highlanders 660 (55%). Most 661 (55.4%) of the migrants visited two and more farm sites during their stay at development corridors for harvesting activities. Approximately 116 (54.7%) asymptomatic malaria cases returned to the Dembia 46 (21.7%), Chilaga 46 (19.8%) and Metema 28 (13.2%) districts.

Conclusion

In this study, asymptomatic malaria remains high among seasonal migrant workers departing to home from malaria endemic areas. This may fuel a resurgence of malaria transmission in the high lands and cause challenges to the country's malaria prevention and elimination efforts. Hence, tailored interventions for seasonal migrant workers could be in place to enhance malaria control and elimination in Ethiopia, such as asymptomatic malaria test and treat positive cases at departure and transit, and integration between malaria officers at their origin and departure for further follow-up to decrease any risk of spread at the origin.

Understanding the epidemiology, clinical characteristics, knowledge and barriers to treatment and prevention of malaria among returning international laborers in northern Vietnam: a mixed-methods study

Background

With the decline in local malaria transmission in Vietnam as a result of the National Malaria Control Program (NMCP) elimination activities, a greater focus on the importation and potential reintroduction of transmission are essential to support malaria elimination objectives.

Methods

We conducted a multi-method assessment of the demographics, epidemiology, and clinical characteristics of imported malaria among international laborers returning from African or Southeast Asian countries to Vietnam. Firstly, we conducted a retrospective review of hospital records of patients from January 2014 to December 2016. Secondly, we conducted a mixed-methods prospective study for malaria patients admitted to the study sites from January 2017 to May 2018 using a structured survey with blood sample collection for PCR analysis and in-depth interviews. Data triangulation of the qualitative and quantitative data was used during analysis.

Results

International laborers were young (median age 33.0 years IQR 28.0–39.5 years), predominantly male (92%) adults returning mostly from the African continent (84%) who stayed abroad for prolonged periods (median time 13.5 months; IQR 6.0–331.5 months) and were involved in occupations that exposed them to a higher risk of malaria infection. Epidemiological trends were also similar amongst study strands and included the importation of Plasmodium falciparum primarily from African countries and P. vivax from Southeast Asian countries. Of 11 P. malariae and P. ovale infections across two study strands, 10 were imported from the African continent. Participants in the qualitative arm demonstrated limited knowledge about malaria prior to travelling abroad, but reported knowledge transformation through personal or co-worker’s experience while abroad. Interestingly, those who had a greater understanding of the severity of malaria presented to the hospital for treatment sooner than those who did not; median of 3 days (IQR 2.0–7.0 days) versus 5 days (IQR 4.0–9.5 days) respectively.

Conclusion

To address the challenges to malaria elimination raised by a growing Vietnamese international labor force, consideration should be given to appropriately targeted interventions and malaria prevention strategies that cover key stages of migration including pre-departure education and awareness, in-country prevention and prophylaxis, and malaria screening upon return.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07322-5.

Assessment of electronic surveillance and knowledge, attitudes, and practice (KAP) survey toward imported malaria surveillance system acceptance in France

Objective

An electronic surveillance system was released to monitor morbidity and mortality incidence of imported malaria cases, investigate autochthonous cases, and assess chemosensitivity of Plasmodium isolates among travelers to and from endemic areas. The aim of this study is to evaluate the use of an electronic surveillance system for imported malaria in France.

Materials and Methods

Three main indicators were used to assess the online malaria web-based surveillance system: (1) the quality of the surveillance system; (2) the capacity of the online system to early warning in case of particular events of public health; (3) the knowledge, attitude, and practice of online electronic system by practitioners of malaria network in France.

Results

Overall, the median time onset a case is reported to the system decrease by 99%, ranging from 227 days (144–309) to 2 days (1–6) in 2006 and 2020, respectively.

Conclusion

The online malaria surveillance system in France has demonstrated its effectiveness and can therefore be extended to carry out numerous investigations linked to research on malaria.

We describe the surveillance activities of the imported malaria surveillance in travelers from and to endemic areas in France caused by the bite of infected mosquitoes. Furthermore, we evaluate how the participants to the network navigate, appreciate, and report their diagnosed cases to the French National Reference Center for malaria. The main findings are the stability of the network from 1996 through 2020; the reduction of the time between the diagnosis and the declaration of the case in the database. This study provides the effectiveness and ability of this surveillance system to carry out numerous investigations linked to research on malaria and the willingness of their members to participate in the surveillance of imported malaria.

Circulation of an artemisinin-resistant malaria lineage in a traveller returning from East Africa to France

A returned traveller to Uganda presented with a Plasmodium falciparum kelch13 A675V mutant infection that exhibited delayed clearance under artesunate therapy. Parasites were genetically related to recently reported Ugandan artemisinin-resistant A675V parasites. Adequate malaria prevention measures and clinical and genotypic surveillance are important tools to avoid and track artemisinin resistance.

Promising New Antimalarial Combination Drugs: Garlic And Arteether in Pregnant Mice Infected with Plasmodium berghei

BACKGROUND

Antimalarial prescription remains a challenge in pregnant women because of maternal and fetal complications. Recently, garlic and α-β-arteether combination treatment in malaria-infected mice conferred protection. The purpose of this study is to evaluate the efficacy of these drugs during pregnancy malaria and its safety measures.

OBJECTIVE

The study is to evaluate the efficacy of arteether and garlic combination drugs in protection against malaria infected pregnant mice.

METHODS

Plasmodium berghei-infected pregnant mouse model was used to assess the combination drug efficacy and the outcome of abnormalities of the disease after drug treatment. After optimizing the dose and gestation period, maternal protection was confirmed by parasite clearance in smear and mortality observation. In addition, maternal hematological parameters, different organ histopathology and IgG levels were documented along with the fetal and infant outcomes.

RESULTS

Arteether monotherapy led to spontaneous fetal abortion or resorption but after the dose optimization and with garlic combination has resulted in completion of the pregnancy and protection against malaria. The derangements observed in the histoarchitecture of organs and hematological parameters caused by malaria infection revealed improvement after drug treatment and the smear observation confirms the clearance of malaria parasite in the peripheral blood, but IgG level was maintained at the same higher level as in malaria-infected mice.

CONCLUSIONS

The first report of arteether and garlic combination promising high efficacy in protection against malaria-infected pregnant mice ascertain their safety and an effective alternative for pregnancy-associated malaria.

Evaluating the efficacy of rapid diagnostic tests for imported malaria in high income countries: A systematic review

BACKGROUND

Malaria is a life-threatening disease. Prior to the pandemic, over a million people annually from non-endemic, high income countries such as Europe and North America visited countries with a risk of malaria transmission. Emergency care nurses in non-endemic countries frequently encounter returning travellers, presenting with symptoms suggestive of malaria. While rapid diagnostic tests are used in countries with endemic malaria, in countries such as the United Kingdom diagnosis is undertaken by microscopy and three negative tests are required to exclude.

QUESTION

Are rapid diagnostic tests effective for diagnosing imported malaria in non-endemic, high income countries?

METHOD

A systematic review of published research (January 2009 - November 2020) comparing rapid diagnostic tests with microscopy.

RESULTS

Fourteen studies were included, conducted in five countries with 14 different RDTs evaluated. Mean sensitivity and specificity for Plasmodium Falciparum was 91.8% and 97.7% and Plasmodium Vivax 81.6% and 99.2%. Higher sensitivities were related to higher parasite densities.

CONCLUSIONS

International travel will return post-pandemic and rapid, accurate and cost-efficient tests will be required. The rapid diagnostic tests in these studies showed significant variation and were not as accurate as microscopy. Consequently, it cannot be recommended that rapid diagnostic tests replace the gold standard of microscopy. Further research is required.

Barriers to seeking health care among returning travellers with malaria: A systematic review

OBJECTIVE

To identify barriers to seeking health care among returning travellers with malaria with the aim of developing targeted interventions that improve early health care-seeking behaviour, diagnosis and treatment.

METHODS

Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we conducted a systematic review of published medical literature, selecting studies that investigated and reported barriers to seeking health care among returning travellers and migrants with malaria. In total, 633 articles were screened, of which four studies met the inclusion criteria after a full-text review.

RESULTS

The four studies reported barriers to seeking healthcare among returning travellers in China, the United States, Thailand and the Dominican Republic. Three studies had an observational design. The identified barriers were summarised based on the appraisal delay, illness delay and utilisation delay stages. During appraisal delays, low awareness of malaria was the most significant factor. Once the patient assessed that he or she was ill, belonging to a specific minority ethnicity, being infected with P. vivax and receiving a low level of social support were predictors of delayed health care-seeking. Finally, the most significant factor associated with utilisation delays was the monetary cost.

CONCLUSION

The health care-seeking behaviour of returning travellers with malaria should be further investigated and improved. Addressing the identified barriers and gaps in health care-seeking behaviour among returning travellers with malaria, particularly among groups at high risk of travel-associated infections, is important to prevent severe disease and deaths as well as secondary transmission and epidemics.

A genotyping assay to determine geographic origin and transmission potential of Plasmodium falciparum malaria cases

As countries work towards malaria elimination, it is important to monitor imported cases to prevent reestablishment of local transmission. The Plasmodium falciparum Pfs47 gene has strong geographic population structure, because only those parasites with Pfs47 haplotypes compatible with the mosquito vector species in a given continent are efficiently transmitted. Analysis of 4,971 world-wide Pfs47 sequences identified two SNPs (at 707 and 725 bp) as sufficient to establish the likely continent of origin of P. falciparum isolates. Pfs47 sequences from Africa, Asia, and the New World presented more that 99% frequency of distinct combinations of the SNPs 707 and 725 genotypes. Interestingly, Papua New Guinea Pfs47 sequences have the highest diversity in SNPs 707 and 725. Accurate and reproducible High-Resolution Melting (HRM) assays were developed to genotype Pfs47 SNPs 707 and 725 in laboratory and field samples, to assess the geographic origin and risk of local transmission of imported P. falciparum malaria cases.

Imported Malaria in Portugal: Prevalence of Polymorphisms in the Anti-Malarial Drug Resistance Genes pfmdr1 and pfk13

Malaria is one of the ‘big three’ killer infectious diseases, alongside tuberculosis and HIV. In non-endemic areas, malaria may occur in travelers who have recently been to or visited endemic regions. The number of imported malaria cases in Portugal has increased in recent years, mostly due to the close relationship with the community of Portuguese language countries. Samples were collected from malaria-infected patients attending Centro Hospitalar Lisboa Ocidental (CHLO) or the outpatient clinic of Instituto de Higiene e Medicina Tropical (IHMT-NOVA) between March 2014 and May 2021. Molecular characterization of Plasmodium falciparum pfk13 and pfmdr1 genes was performed. We analyzed 232 imported malaria cases. The majority (68.53%) of the patients came from Angola and only three patients travelled to a non-African country; one to Brazil and two to Indonesia. P. falciparum was diagnosed in 81.47% of the cases, P. malariae in 7.33%, P. ovale 6.47% and 1.72% carried P. vivax. No mutations were detected in pfk13. Regarding pfmdr1, the wild-type haplotype (N86/Y184/D1246) was also the most prevalent (64.71%) and N86/184F/D1246 was detected in 26.47% of the cases. The typical imported malaria case was middle-aged male, traveling from Angola, infected with P. falciparum carrying wild type pfmdr1 and pfk13. Our study highlights the need for constant surveillance of malaria parasites imported into Portugal as an important pillar of public health.

A comprehensive insight on the biological potential of embelin and its derivatives

Naturally occurring bioactive molecules are known for their diverse biological applications such as antimicrobial, anticancer, anti-inflammatory, and analgesic activities. Also, some of the natural products act as medicinal drugs. Further, bioactive cell-permeable molecule embelin has been reported for its diverse biological activities such as antimalarial, anticancer, and anti-inflammatory in the literature. With the continuation of our research work on biologically active molecules, based on structural activity relationship and docking studies of embelin and its derivatives, we have reported target-specific anticancer and antimalarial activities of embelin and its analogs. Also, it has been reported in many recent research articles that embelin and its derivatives are known to possess medicinal properties. This review mainly highlights recent reports on broad-spectrum biological activities of the embelin and its analogs to date.

Epidemiological profile of imported malaria cases in the prevention of reestablishment phase in Sri Lanka

Sri Lanka reported the last case of indigenous malaria in October 2012, and received malaria-free certification from WHO in September 2016. Malaria cases have since, shifted from indigenous to imported, and the country remains receptive and vulnerable to malaria. A case-based epidemiological study was conducted on all imported malaria cases reported in the country in 2015 and 2016 with the aim of profiling imported malaria to improve the effectiveness of the surveillance and case management system for malaria. Data were obtained from case reports of the Anti Malaria Campaign, hospital records and laboratory registers. Over the 2 years, 77 imported malaria infections were diagnosed in 54 Sri Lankans and 23 foreign nationals. A majority of the infections were reported among males (93%) in the age group of 21-50 years (85.8%), and all were recent travelers overseas. Most patients were detected by passive case detection, but 10% of cases were detected by Active Case Detection. Only 25% of patients were diagnosed within 3 days of the onset of symptoms. In 32% of patients, the diagnosis was delayed by more than 10 days after the onset of symptoms. Plasmodium falciparum infections manifested significantly earlier after arrival in Sri Lanka than did P.vivax infections. The majority of patients (74%) were diagnosed in the Western Province, which was not endemic for malaria. A third of patients were diagnosed in the private sector. The shift in the epidemiology of malaria infection from before to after elimination has implications for preventing the reestablishment of malaria.

Mobile apps for travel medicine and ethical considerations: A systematic review

BACKGROUND

The advent of mobile applications for health and medicine will revolutionize travel medicine. Despite their many benefits, such as access to real-time data, mobile apps for travel medicine are accompanied by many ethical issues, including questions about security and privacy.

METHODS

A systematic literature review as conducted following PRISMA guidelines. Database screening yielded 1795 results and seven papers satisfied the criteria for inclusion. Through a mix of inductive and deductive data extraction, this systematic review examined both the benefits and challenges, as well as ethical considerations, of mobile apps for travel medicine.

RESULTS

Ethical considerations were discussed with varying depth across the included articles, with privacy and data protection mentioned most frequently, highlighting concerns over sensitive information and a lack of guidelines in the digital sphere. Additionally, technical concerns about data quality and bias were predominant issues for researchers and developers alike. Some ethical issues were not discussed at all, including equity, and user involvement.

CONCLUSION

This paper highlights the scarcity of discussion around ethical issues. Both researchers and developers need to better integrate ethical reflection at each step of the development and use of health apps. More effective oversight mechanisms and clearer ethical guidance are needed to guide the stakeholders in this endeavour.

The Pan African Vivax and Ovale Network (PAVON): Refocusing on Plasmodium vivax, ovale and asymptomatic malaria in sub-Saharan Africa

The recent World Malaria report shows that progress in malaria elimination has stalled. Current data acquisition by NMCPs depend on passive case detection and clinical reports focused mainly on Plasmodium falciparum (Pf). In recent times, several countries in sub-Saharan Africa have reported cases of Plasmodium vivax (Pv) with a considerable number being Duffy negative. The burden of Pv and Plasmodium ovale (Po) appear to be more than acknowledged. Similarly, the contribution of asymptomatic malaria in transmission is hardly considered by NMCPs in Africa. Inclusion of these as targets in malaria elimination agenda is necessary to achieve elimination goal, as these harbor hypnozoites. The Pan African Vivax and Ovale Network (PAVON) is a new consortium of African Scientists working in Africa on the transmission profile of Pv and Po. The group collaborates with African NMCPs to train in Plasmodium molecular diagnostics, microscopy, and interpretation of molecular data from active surveys to translate into policy. Details of the mission, rational and modus operandi of the group are outlined.

Analysing human population movement data for malaria control and elimination

BACKGROUND

Human population movement poses a major obstacle to malaria control and elimination. With recent technological advances, a wide variety of data sources and analytical methods have been used to quantify human population movement (HPM) relevant to control and elimination of malaria.

METHODS

The relevant literature and selected studies that had policy implications that could help to design or target malaria control and elimination interventions were reviewed. These studies were categorized according to spatiotemporal scales of human mobility and the main method of analysis.

RESULTS

Evidence gaps exist for tracking routine cross-border HPM and HPM at a regional scale. Few studies accounted for seasonality. Out of twenty included studies, two studies which tracked daily neighbourhood HPM used descriptive analyses as the main method, while the remaining studies used statistical analyses or mathematical modelling.

CONCLUSION

Although studies quantified varying types of human population movement covering different spatial and temporal scales, methodological gaps remain that warrant further studies related to malaria control and elimination.