Prevention of Malaria Resurgence in Greece through the Association of Mass Drug Administration (MDA) to Immigrants from Malaria-Endemic Regions and Standard Control Measures

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.

Genetic Structure of Introduced Plasmodium vivax Malaria Isolates in Greece, 2015-2019

Greece has been malaria-free since 1974, after an intense malaria control program. However, as Greece hosts migrant populations from P. vivax malaria-endemic countries, there is a risk of introducing the disease to specific vulnerable and receptive areas of the country. Knowledge of the genetic diversity of P. vivax populations is essential for understanding the dynamics of malaria disease transmission in a given region. We used nine highly polymorphic markers to genotype 124 P. vivax-infected archived DNA samples from human blood specimens referred to the NMRL from all over Greece throughout 2015-2019. The genotypic variability of the samples studied was noted, as they comprised several unique haplotypes, indicative of the importation of a large number of different P. vivax strains in the country. However, only a few events of local transmission were recorded. Genotyping revealed and confirmed the same clusters as those identified through epidemiological investigation. In only one introduction event was the index case found. No sustained/ongoing malaria transmissions in/between the studied regions or during consecutive years or additional foci of local transmission were observed. Genotyping is an important component in assisting malaria surveillance, as it provides information concerning the patterns of introduction and the effectiveness of implemented malaria control and elimination measures.

Targeted Drug Administration to Reduce Malaria Transmission: A Systematic Review and Meta-Analysis

In low- to very low-malaria transmission areas, most infections may be accrued within specific groups whose behaviors or occupations put them at increased risk of infection. If these infections comprise a large proportion of the reservoir of infection, targeting interventions to these groups could reduce transmission at the population level. We conducted a systematic review to assess the impact of providing antimalarials to groups of individuals at increased risk of malaria whose infections were considered to comprise a large proportion of the local reservoir of infections (targeted drug administration [TDA]). A literature search was conducted in March 2021 and updated in April 2022. Two reviewers screened titles, abstracts, and full-text records. The Grading of Recommendations Assessment, Development and Evaluation approach was used to rate the certainty of the evidence (CoE) for each outcome. Out of 2,563 records, we identified five studies for inclusion: two cluster-randomized controlled trials (cRCTs) in Uganda and Kenya; one controlled before-after study in Ghana; and two uncontrolled before-after studies in Sri Lanka and Greece. Compared with no intervention, TDA resulted in little to no difference in the prevalence of infection at the population level (risk ratio [RR]: 0.85, 95% CI: 0.73-1.00; one cRCT, high CoE), although TDA likely resulted in a large reduction in prevalence among those targeted by the intervention (RR: 0.15, 95% CI: 0.06-0.38; two cRCTs, moderate CoE). Although TDA may reduce the burden of malaria among those receiving antimalarials, we found no evidence that it reduces transmission at the population level.

Use of rapid diagnostic tests for the detection of ancient malaria infections in dental pulp from the sixth century in Versailles, France

BACKGROUND

Paleomicrobiological data have clarified that Plasmodium spp. was circulating in the past in southern European populations, which are now devoid of malaria. The aim of this study was to evaluate the efficacy of immunodetection and, more particularly, rapid diagnostic tests (RDT), in order to further assess Plasmodium infections in ancient northern European populations.

METHODS

A commercially available RDT, PALUTOP^® + 4 OPTIMA, which is routinely used to detect malaria, was used to detect Plasmodium antigens from proteins recovered from ancient specimens extracted from 39 dental pulp samples. These samples were collected from 39 individuals who were buried in the sixth century, near the site of the current Palace of Versailles in France. Positive and negative controls were also used. Antigens detected were quantified using chemiluminescence imaging system analysis.

RESULTS

Plasmodium antigens were detected in 14/39 (35.9%) individuals, including Plasmodium vivax antigens in 11 individuals and Plasmodium falciparum antigens co-detected in two individuals, while Pan-Plasmodium antigens were detected in three individuals. Controls all yielded expected results.

CONCLUSIONS

The data reported here showed that RDTs are a suitable tool for detecting Plasmodium spp. antigens in ancient dental pulp samples, and demonstrated the existence of malaria in Versailles, France, in the sixth century. Plasmodium vivax, which is regarded as being responsible for an attenuated form of malaria and less deadly forms, was the most prevalent species. This illustrates, for the first time in ancient populations, co-infection with P. falciparum, bringing into question the climate-driven ecosystems prevailing at that time in the Versailles area.

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.

The changing risk patterns of Plasmodium vivax malaria in Greece due to climate change

It has great importance to study the potential effects of climate change on Plasmodium vivax malaria in Greece because the country can be the origin of the spread of vivax malaria to the northern areas. The potential lengths of the transmission seasons of Plasmodium vivax malaria were forecasted for 2041-2060 and 2061-2080 and were combined. The potential ranges were predicted by Climate Envelope Modelling Method. The models show moderate areal increase and altitudinal shift in the malaria-endemic areas in Greece in the future. The length of the transmission season is predicted to increase by 1 to 2 months, mainly in the mid-elevation regions and the Aegean Archipelago. The combined factors also predict the decrease of vivax malaria-free area in Greece. It can be concluded that rather the elongation of the transmission season will lead to an increase of the malaria risk in Greece than the increase in the suitability values.

Usability of a point-of-care diagnostic to identify glucose-6-phosphate dehydrogenase deficiency: a multi-country assessment of test label comprehension and results interpretation

Background

Point-of-care glucose-6-phosphate dehydrogenase (G6PD) testing has the potential to make the use of radical treatment for vivax malaria safer and more effective. Widespread use of G6PD tests as part of malaria case management has been limited, in part due to due concerns regarding product usability, user training, and supervision. This study seeks to assess how well end users can understand the Standard™ G6PD Test (SD Biosensor, Suwon, South Korea) workflow, result output, and label after training. This will ultimately help inform test registration and introduction.

Methods

Potential G6PD test users who provide malaria case management at three sites in Brazil, Ethiopia, and India were trained on the use of the SD Biosensor Standard G6PD Test and assessed based on their ability to understand the test workflow and interpret results. The assessment was done through a questionnaire, designed to assess product usability against key technical product specifications and fulfill regulatory evidence requirements. Any participant who obtained 85% or above correct responses to the questionnaire was considered to adequately comprehend how to use and interpret the test.

Results

Forty-five participants, including malaria microscopists, laboratory staff, nurses, and community health workers took part in the study. Seventy-eight percent of all participants in the study (35/45) obtained passing scores on the assessment with minimal training. Responses to the multiple-choice questions indicate that most participants understood well the test intended use, safety claims, and warnings. The greatest source of error regarding the test was around the correct operating temperature. Most test results were also read and interpreted correctly, with the haemoglobin measurement being a more problematic output to interpret than the G6PD measurement.

Conclusions

These data results show how a standardized tool can be used to assess a user’s ability to run a point-of-care diagnostic and interpret results. When applied to the SD Biosensor Standard G6PD Test, this tool demonstrates that a range of users across multiple contexts can use the test and suggests improvements to the test instructions and training that can improve product usability, increase user comprehension, and ultimately contribute to more widespread effective use of point-of-care G6PD tests.

Trial registration: NCT04033640

The Importance of an Active Case Detection (ACD) Programme for Malaria among Migrants from Malaria Endemic Countries: The Greek Experience in a Receptive and Vulnerable Area

Greece has been malaria-free since 1974. In October 2011, following an outbreak of 36 locally acquired malaria (LAM) cases in Evrotas Municipality, a Pro-Active Case Detection (PACD) program for malaria was implemented among migrants from malaria-endemic countries, to support early diagnosis and treatment of cases. We evaluated the PACD program for the years 2012–2017 using indicators such as the number of locally acquired cases, the detection rate/sensitivity and the timeliness of diagnosis and treatment. We visited each migrant home every 7–15 days to screen migrants for malaria symptoms, performing Rapid Diagnostic Tests (RDTs) and blood smears on symptomatic patients. We estimated: (i) the number of malaria cases detected by the PACD, divided by the total number of reported malaria cases during the same period among the same population; (ii) the time between onset of symptoms, diagnosis and initiation of treatment. The total number of migrants who were screened for malaria symptoms for the years 2012–2017 was 5057 with 84,169 fever screenings conducted, while 2288 RDTs and 1736 blood smears were performed. During the same period, 53 imported P. vivax malaria cases were detected, while incidence of malaria among migrants was estimated at 1.8% annually. Ten and one LAM cases were also reported in 2012 and 2015, respectively. Sensitivity of PACD ranged from 86% to 100%; median timeliness between onset of symptoms and diagnosis decreased from 72 h in 2012 to 12 h in 2017 (83% decrease), while timeliness between diagnosis and treatment initiation was 0 h. The implementation of PACD could be considered an effective prevention and response tool against malaria re-introduction.

Unexplored Opportunities: Use of Climate- and Weather-Driven Early Warning Systems to Reduce the Burden of Infectious Diseases

PURPOSE OF REVIEW

Weather and climate influence multiple aspects of infectious disease ecology. Creating and applying early warning systems based on temperature, precipitation, and other environmental data can identify where and when outbreaks of climate-sensitive infectious diseases could occur and can be used by decision makers to allocate resources. Whether an outbreak actually occurs depends heavily on other social, political, and institutional factors.

RECENT FINDINGS

Improving the timing and confidence of seasonal climate forecasting, coupled with knowledge of exposure-response relationships, can identify prior conditions conducive to disease outbreaks weeks to months in advance of outbreaks. This information could then be used by public health professionals to improve surveillance in the most likely areas for threats. Early warning systems are well established for drought and famine. And while weather- and climate-driven early warning systems for certain diseases, such as dengue fever and cholera, are employed in some regions, this area of research is underdeveloped. Early warning systems based on temperature, precipitation, and other environmental data provide an opportunity for early detection leading to early action and response to potential pathogen threats, thereby reducing the burden of disease when compared with passive health indicator-based surveillance systems.

Genetic Spatiotemporal Anatomy of Plasmodium vivax Malaria Episodes in Greece, 2009-2013

An influx of immigrants is contributing to the reemergence of Plasmodium vivax malaria in Greece; 1 persistent focus of transmission is in Laconia, Pelopónnese. We genotyped archived blood samples from a substantial proportion of malaria cases recorded in Greece in 2009–2013 using 8 microsatellite markers and a PvMSP-3α gene fragment and plotted their spatiotemporal distribution. High parasite genetic diversity with low multiplicity of infection was observed. A subset of genetically identical/related parasites was restricted to 3 areas in migrants and Greek residents, with some persisting over 2 consecutive transmission periods. We identified 2 hitherto unsuspected additional foci of local transmission: Kardhítsa and Attica. Furthermore, this analysis indicates that several cases in migrants initially classified as imported malaria were actually locally acquired. This study shows the potential for P. vivax to reestablish transmission and counsels public health authorities about the need for vigilance to achieve or maintain sustainable malaria elimination.

Travel, Migration and Emerging Infectious Diseases

Emerging infectious diseases (EID) threaten public health and are sustained by increasing global commerce, travel and disruption of ecological systems. Travelers could play a role in importing EIDs and could be a sentinel of major epidemics. In connection with the extension of poverty, urbanization, extensive livestock rearing and globalization, we could be exposed to a third epidemiological transition characterized by zoonotic diseases and infections with multidrug-resistant bacteria. The risk appears low for emerging infectious diseases, or very low for high-risk emerging infectious diseases, but higher for multidrug-resistant enterobacteriaceae carriage with possibly limited consequences. The role played by migrants is weaker than imagined. Immigrants don't play the role of sentinel epidemic so far. They could play a role in importing multidrug-resistant enterobacteriaceae, but it is poorly evaluated.

A primer on multiscale modelling of infectious disease systems

The development of multiscale models of infectious disease systems is a scientific endeavour whose progress depends on advances on three main frontiers: (a) the conceptual framework frontier, (b) the mathematical technology or technical frontier, and (c) the scientific applications frontier. The objective of this primer is to introduce foundational concepts in multiscale modelling of infectious disease systems focused on these three main frontiers. On the conceptual framework frontier we propose a three-level hierarchical framework as a foundational idea which enables the discussion of the structure of multiscale models of infectious disease systems in a general way. On the scientific applications frontier we suggest ways in which the different structures of multiscale models can serve as infrastructure to provide new knowledge on the control, elimination and even eradication of infectious disease systems, while on the mathematical technology or technical frontier we present some challenges that modelers face in developing appropriate multiscale models of infectious disease systems. We anticipate that the foundational concepts presented in this primer will be central in articulating an integrated and more refined disease control theory based on multiscale modelling - the all-encompassing quantitative representation of an infectious disease system.

Malaria Elimination: Time to Target All Species

Important strides have been made within the past decade toward malaria elimination in many regions, and with this progress, the feasibility of eradication is once again under discussion. If the ambitious goal of eradication is to be achieved by 2040, all species of Plasmodium infecting humans will need to be targeted with evidence-based and concerted interventions. In this perspective, the potential barriers to achieving global malaria elimination are discussed with respect to the related diversities in host, parasite, and vector populations. We argue that control strategies need to be reorientated from a sequential attack on each species, dominated by Plasmodium falciparum to one that targets all species in parallel. A set of research themes is proposed to mitigate the potential setbacks on the pathway to a malaria-free world.

A spatial predictive model for malaria resurgence in central Greece integrating entomological, environmental and social data

Malaria constitutes an important cause of human mortality. After 2009 Greece experienced a resurgence of malaria. Here, we develop a model-based framework that integrates entomological, geographical, social and environmental evidence in order to guide the mosquito control efforts and apply this framework to data from an entomological survey study conducted in Central Greece. Our results indicate that malaria transmission risk in Greece is potentially substantial. In addition, specific districts such as seaside, lakeside and rice field regions appear to represent potential malaria hotspots in Central Greece. We found that appropriate maps depicting the basic reproduction number, R₀, are useful tools for informing policy makers on the risk of malaria resurgence and can serve as a guide to inform recommendations regarding control measures.

Prophylactic efficacy of primaquine for preventing Plasmodium falciparum and Plasmodium vivax parasitaemia in travelers: A meta-analysis and systematic review

BACKGROUND

With increased international travel over the world the need for safe and effective chemoprophylaxis for malaria is as great as ever. The choice of regimen is difficult, as effectiveness should be weighted against potential adverse effects. Although, some studies have reported high prophylactic efficacy of primaquine, there is no comprehensive evidence comparing its prophylactic effectiveness as well as toxicity. To fill the gap, this systematic review and meta-analysis study was carried out.

METHODS

Using MeSH terms, 756 records were detected through searching "Pubmed", "Embase","Web of Science"and "Cochrane" databases. From these,7 relevant full-text articles with 14 comparisons for final quantitative meta-analysis were included in our review. In order to make a comparison between the studies, Risk Ratios(RRs) and their 95% confidence intervals(CIs) were estimated.

RESULTS

Overall,74% reduction in the incidence of parasitaemia by primaquine versus other prophylactic regimens was estimated(RRoverall = 0.26, CI 95%:0.16-0.41--RRvivax = 0.16, CI 95%:0.07-0.36--RRfalciparum = 0.31, CI 95%:0.18-0.55). The incidence rate ratios for adverse effects showed no statistically significant difference between primaquine and control groups (p > 0.05).

CONCLUSIONS

For persons without G6PD deficiency, who are not pregnant, primaquine is the most effective presently available prophylactic for P. vivax malaria and comparable to such regimens as doxycycline, mefloquine and atovaquone-proguanil for the prevention of P. falciparum malaria.

Does antimalarial mass drug administration increase or decrease the risk of resistance?

All antimalarial drugs developed so far have eventually succumbed to resistance. There is a general belief that the more people that are exposed to an antimalarial drug, the more likely it is that resistance will emerge. Mass drug administration (MDA) is therefore considered a potent cause of antimalarial drug resistance. In this Personal View, I discuss the circumstances under which antimalarial MDA increases or decreases the risk of resistance. It is the total number of parasites exposed and their individual probabilities of survival and spread that determine the risk, not the number of people that contain them. In malaria-endemic areas, a substantial proportion of the community carries malaria parasites in their blood without being ill. Although many more people have asymptomatic than symptomatic malaria at any time, their parasite burdens are several orders of magnitude lower, and their host defence mechanisms are substantially more effective. Symptomatic infections with high parasite numbers are the most likely source of resistance emergence, so effective mass treatment that reduces the number of symptomatic cases of malaria and its transmission can reduce the threat of antimalarial resistance emerging and spreading in treated populations.

Observed and projected drivers of emerging infectious diseases in Europe

Emerging infectious diseases are of international concern because of the potential for, and impact of, pandemics; however, they are difficult to predict. To identify the drivers of disease emergence, we analyzed infectious disease threat events (IDTEs) detected through epidemic intelligence collected at the European Centre for Disease Prevention and Control (ECDC) between 2008 and 2013, and compared the observed results with a 2008 ECDC foresight study of projected drivers of future IDTEs in Europe. Among 10 categories of IDTEs, foodborne and waterborne IDTEs were the most common, vaccine-preventable IDTEs caused the highest number of cases, and airborne IDTEs caused the most deaths. Observed drivers for each IDTE were sorted into three main groups: globalization and environmental drivers contributed to 61% of all IDTEs, public health system drivers contributed to 21%, and social and demographic drivers to 18%. A multiple logistic regression analysis showed that four of the top five drivers for observed IDTEs were in the globalization and environment group. In the observational study, the globalization and environment group was related to all IDTE categories, but only to five of eight categories in the foresight study. Directly targeting these drivers with public health interventions may diminish the chances of IDTE occurrence from the outset.

The infectious risks in blood transfusion as of today - A no black and white situation

Transfusion has been tainted with the risk of contracting an infection - often severe - and fears about this risk are still prevailing, in sharp contrast with the actual risk in Western countries. Those actual risks are rather immunological, technical (overload) or metabolic. Meanwhile, in developing countries and particularly in Africa, transfusion transmitted infections (TTIs) are still frequent, because of both the scarcity of volunteer blood donors and resources and the high incidence and prevalence of infections. Global safety of blood components has been declared as a goal to be attained everywhere by the World Heath Organization (WHO). However, this challenge is difficult to meet because of several intricate factors, of which the emergence of infectious agents, low income and breaches in sanitation and hygiene. This review aims at encompassing the situation of TTIs in different settings and means that can be deployed to improve the situation where this can possibly be.

Impact of using artemisinin-based combination therapy (ACT) in the treatment of uncomplicated malaria from Plasmodium falciparum in a non-endemic zone

BACKGROUND

Artemisinin-based combination therapy (ACT) has been adopted by the World Health Organization as a first-line treatment for uncomplicated Plasmodium falciparum malaria. In endemic regions, it has proven more effective in treating the disease, and even in reducing its transmission. Nonetheless, there is a scarcity of studies carried out in non-endemic areas on imported uncomplicated malaria.

METHODS

This is a retrospective, observational study performed on patients diagnosed and admitted with uncomplicated P. falciparum malaria between 2004 and 2015. The objective was to compare the parasite clearance period and the average hospital length of stay for patients treated with ACT vs those receiving other treatment regimens.

RESULTS

Eighty-five patients were included in the study. Fifty-one received ACT treatment (dihydroartemisinin-piperaquine) and thirty-four patients were treated with quinine sulfate+doxycycline or atovaquone/proguanil. The parasite clearance period was shorter in the group of patients treated with ACT compared to those receiving other treatment types: 24 h (IQR 24) vs 48 h (IQR 48), p < 0.01. The average hospital stay was also shorter in the ACT group with respect to the second group: 2.67 days (IQR 1.08) vs 3.96 days (IQR 2.87), p < 0.001. A mild case of hepatitis was registered in the group treated with ACT.

CONCLUSIONS

ACT treatment of admitted hospital patients with imported uncomplicated malaria from P. falciparum reduced the days spent hospitalized as well as producing a more rapid parasite clearance compared to classic treatment. In spite of being treated with safe medications, one has to be alert to possible adverse effects such as hepatitis and delayed haemolytic anaemia.

Malaria in Europe: emerging threat or minor nuisance?

Malaria was eradicated from Europe in the 1970s through a combination of insecticide spraying, drug therapy and environmental engineering. Since then, it has been mostly imported into the continent by international travellers and immigrants from endemic regions. Despite the substantial number of imported malaria cases and the documented presence of suitable anopheline vectors, autochthonous transmission has not been widely observed in Europe, probably as a result of early diagnosis and treatment, afforded by efficient healthcare systems. Current climatic conditions are conducive to malaria transmission in several areas of Southern Europe, and climate change might favour mosquito proliferation and parasite development, further facilitating malaria transmission. Moreover, the continuing massive influx of refugee and migrant populations from endemic areas could contribute to building up of an infectious parasite reservoir. Although the malariogenic potential of Europe is currently low, particularly in the northern and western parts of the continent, strengthening of disease awareness and maintaining robust public health infrastructures for surveillance and vector control are of the utmost importance and should be technically and financially supported to avert the possibility of malaria transmission in Europe's most vulnerable areas.

The risk of imported malaria in security forces personnel returning from overseas missions in the context of prevention of re-introduction of malaria to Sri Lanka

Background

Sri Lanka is a malaria-free country. However it remains surrounded by countries with endemic malaria transmission. Since the last indigenous case of malaria was reported in October 2012, only imported malaria cases have been diagnosed with 36 cases detected in 2015, which includes 17 cases each of Plasmodium vivax and Plasmodium falciparum and two cases of Plasmodium ovale.

Methods

This study investigated the knowledge and practices regarding malaria chemoprophylaxis among all the Sri Lankan security forces personnel returning from peacekeeping missions in malaria endemic countries over a 7 month period. Adherence to other malaria prevention measures, occurrence of adverse events and incident cases of malaria were also recorded maintaining the anonymity of the respondents. Potential associations for non-compliance were studied.

Results

Interviews were carried out with 559 security forces personnel returning home from foreign deployments in malaria-endemic regions (males: 550, 98.4 %). The majority (553, 98.9 %) was well aware of the need for chemoprophylaxis during the overseas stay and its regular use as prescribed. The overall adherence to chemoprophylaxis was good with 78.7 % (440/559) reporting regular, as prescribed, use. Having better educational qualifications, being female, being prescribed mefloquine, having fever during deployment and belonging to a security force other than the army were significantly associated with poor compliance (p < 0.05).

Conclusions

The study reveals that knowledge regarding malaria chemoprophylaxis among Sri Lankan security forces personnel serving abroad was good, a fact that may have contributed to absence/extremely low incidence of malaria during deployment.