Search

Background: Malaria is still a leading child killer in sub-Saharan Africa. Yet, access to prompt and effective malaria treatment, a mainstay of any malaria control strategy, is sub-optimal in many settings. Little is known about obstacles to treatment and community-effectiveness of case-management strategies. This research quantified treatment seeking behaviour and access to treatment in a highly endemic rural Tanzanian community. The aim was to provide a better understanding of obstacles to treatment access in order to develop practical and cost-effective interventions.Methods: We conducted community-based treatment-seeking surveys including 226 recent fever episodes in 2004 and 2005. The local Demographic Surveillance System provided additional household information. A census of drug retailers and health facilities provided data on availability and location of treatment sources.Results: After intensive health education, the biomedical concept of malaria has largely been adopted by the community. 87.5% (78.2-93.8) of the fever cases in children and 80.7% (68.1-90.0) in adults were treated with one of the recommended antimalarials (at the time SP, amodiaquine or quinine). However, only 22.5% (13.9-33.2) of the children and 10.5% (4.0-21.5) of the adults received prompt and appropriate antimalarial treatment. Health facility attendance increased the odds of receiving an antimalarial (OR = 7.7) but did not have an influence on correct dosage. The exemption system for under-fives in public health facilities was not functioning and drug expenditures for children were as high in health facilities as with private retailers.Conclusion: A clear preference for modern medicine was reflected in the frequent use of antimalarials. Yet, quality of case-management was far from satisfactory as was the functioning of the exemption mechanism for the main risk group. Private drug retailers played a central role by complementing existing formal health services in delivering antimalarial treatment. Health system factors like these need to be tackled urgently in order to translate the high efficacy of newly introduced artemisinin-based combination therapy (ACT) into equitable community-effectiveness and health-impact. [ABSTRACT FROM AUTHOR]

Artemisinin-based combination therapies (ACTs) were introduced as the standard of care for uncomplicated malaria in Africa almost two decades ago. Recent studies in East Africa have reported a gradual increase in kelch13 ( k13 ) mutant parasites associated with reduced artesunate efficacy. As part of the Community Access to Rectal Artesunate for Malaria project, we collected blood samples from 697 children with signs of severe malaria in northern Uganda between 2018 and 2020, before and after the introduction of rectal artesunate (RAS) in 2019. K13 polymorphisms were assessed, and parasite editing and phenotyping were performed to assess the impact of mutations on parasite resistance. Whole-genome sequencing was performed, and haplotype networks were constructed to determine the geographic origin of k13 mutations. Of the 697 children, 540 were positive for Plasmodium falciparum malaria by PCR and were treated with either RAS or injectable artesunate monotherapy followed in most cases by ACT. The most common k13 mutation was C469Y (6.7%), which was detected more frequently in samples collected after RAS introduction. Genome editing confirmed reduced in vitro susceptibility to artemisinin in C469Y-harboring parasites compared to wild-type controls ( P < 0.001). The haplotypic network showed that flanking regions of the C469Y mutation shared the same African genetic background, suggesting a single and indigenous origin of the mutation. Our data provide evidence of selection for the artemisinin-resistant C469Y mutation. The realistic threat of multiresistant parasites emerging in Africa should encourage careful monitoring of the efficacy of artemisinin derivatives and strict adherence to ACT treatment regimens., Competing Interests: The authors declare no conflict of interest.

Genomic epidemiology holds promise for malaria control and elimination efforts, for example by informing on Plasmodium falciparum genetic diversity and prevalence of mutations conferring anti-malarial drug resistance. Limited sequencing infrastructure in many malaria-endemic areas prevents the rapid generation of genomic data. To address these issues, we developed and validated assays for P. falciparum nanopore sequencing in endemic sites using a mobile laboratory, targeting key antimalarial drug resistance markers and microhaplotypes. Using two multiplexed PCR reactions, we amplified six highly polymorphic microhaplotypes and ten drug resistance markers. We developed a bioinformatics workflow that allows genotyping of polyclonal malaria infections, including minority clones. We validated the panels on mock dried blood spot (DBS) and rapid diagnostic test (RDT) samples and archived DBS, demonstrating even, high read coverage across amplicons (range: 580x to 3,212x median coverage), high haplotype calling accuracy, and the ability to explore within-sample diversity of polyclonal infections. We field-tested the feasibility of rapid genotyping in Zanzibar in close collaboration with the local malaria elimination program using DBS and routinely collected RDTs as sample inputs. Our assay identified haplotypes known to confer resistance to known antimalarials in the dhfr, dhps and mdr1 genes, but no evidence of artemisinin partial resistance. Most infections (60%) were polyclonal, with high microhaplotype diversity (median HE = 0.94). In conclusion, our assays generated actionable data within a few days, and we identified current challenges for implementing nanopore sequencing in endemic countries to accelerate malaria control and elimination., Competing Interests: The authors declare that no competing interests exist., (Copyright: © 2024 Holzschuh et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

An increasing number of molecular and genomic assays are available to study malaria parasite populations. However, so far they have played a marginal role in informing policy and programmatic decision-making. Currently, molecular data are mainly used for monitoring drug efficacy against Plasmodium falciparum; assessing molecular markers of drug and insecticide resistance; and assessing P. falciparum histidine-rich protein 2 and 3 genes (Pfhrp2/3) deletion. We argue that additional use cases for molecular routine surveillance could be implemented in the near future, especially in transmission settings approaching elimination. These would include using quantitative polymerase chain reaction to monitor the prevalence of sub-patent infections in asymptomatic carriers, monitoring parasite genetic diversity as transmission intensity is changing, using genomic data to determine the origin of imported infections and characterize transmission chains in settings with very low malaria transmission, and using serology to monitor recent and past exposures in low-transmission settings. Molecular surveillance could inform control programs on adapting novel strategies, such as reactive case detection or focal mass drug administration, and help evaluate the impact of interventions currently in place. To better integrate molecular and genomic data into control program decision-making, engagement of national malaria control experts is crucial. Local laboratory capacity needs to be strengthened, shortening the time from sample collection to data availability. Here, we discuss opportunities and challenges of the use of molecular and genomic data for supporting malaria control and elimination efforts, as well as the avenues to link molecular and genomic data with gold standard epidemiological measurements through mathematical modeling.

Background: Malaria remains a major public health issue in the Democratic Republic of the Congo (DRC), accounting for 44% deaths among outpatient visits in children < 5 years of age, and 22% of facility deaths. Understanding determinants of caregivers' treatment-seeking patterns and decision-making is crucial in reducing the malaria burden., Methods: In the frame of the Community Access to Rectal Artesunate for Malaria (CARAMAL) project, cross-sectional household surveys that randomly sampled villages and households were carried-out in three rural DRC health zones prior to the rollout of pre-referral Rectal Artesunate (RAS) and then 9 and 19 months after RAS rollout (post-RAS). Data were captured electronically through face-to-face interviews with the main caregivers of children < 5 years. Capillary blood samples of the children were tested for malaria and anaemia. The main study outcome was whether caregiver "sought treatment outside home" when the child had fever. Multilevel mixed effects logistic regression models using village as random effect and health zone as a fixed effect was performed to assess treatment-seeking predictors., Results: 2439 household interviews were completed (pre-RAS 888 and post-RAS 1551), including 316 and 653 treatment-seeking interviews. Overall, 3499 children < 5 years were tested for malaria and anaemia (pre-RAS 1,315 and post-RAS 2184). Caregiver's recognition of severe malaria signs was poor, while knowledge of symptoms of uncomplicated malaria seemed high. Despite this, danger signs significantly increased the odds of seeking treatment (aOR = 2.12, 95%CI 1.03-4.38), the same was found for the "least poor" quintile (aOR = 3.01, 95%CI 1.03-8.82), as well as residents of Kingandu (aOR = 2.78, 95%CI 1.01-7.65). "Doing something at home" against fever negatively affected treatment-seeking in both study phases. RAS acceptance was high, at almost 100%. Malaria prevalence was higher post-RAS (45.2%) compared to pre-RAS (34.4%), p = 0.003, but anaemia, although high (≥ 75%), was similar in both study phases (p = 0.92)., Conclusion: In remote communities with high malaria prevalence in the DRC, malaria remains a major problem. Improving the recognition of danger signs of severe disease and introducing pre-referral RAS may improve treatment-seeking and contribute to reducing malaria-related mortality among children-if quality of care can be guaranteed., (© 2023. BioMed Central Ltd., part of Springer Nature.)

Thanks to its expertise in clinical research, epidemiology, infectious diseases, microbiology, parasitology, public health, translational research and tropical medicine, coupled with deeply rooted partnerships with institutions in low- and middle-income countries (LMICs), the Swiss Tropical and Public Health Institute (Swiss TPH) has been a key contributor in many drug research and development consortia involving academia, pharma and product development partnerships. Our know-how of the maintenance of parasites and their life-cycles in the laboratory, plus our strong ties to research centres and disease control programme managers in LMICs with access to field sites and laboratories, have enabled systems for drug efficacy testing in vitro and in vivo, clinical research, and modelling to support the experimental approaches. Thus, Swiss TPH has made fundamental contributions towards the development of new drugs - and the better use of old drugs - for neglected tropical diseases and infectious diseases of poverty, such as Buruli ulcer, Chagas disease, food-borne trematodiasis (e.g. clonorchiasis, fascioliasis and opisthorchiasis), human African trypanosomiasis, leishmaniasis, malaria, schistosomiasis, soil-transmitted helminthiasis and tuberculosis. In this article, we show case the success stories of molecules to which Swiss TPH has made a substantial contribution regarding their use as anti-infective compounds with the ultimate aim to improve people's health and well-being., (Copyright 2023 Pascal Mäser, Sonja Bernhard, Reto Brun, Christian Burri, Sébastien Gagneux, Manuel W. Hetzel, Marcel Kaiser, Christian Lengeler, Gerd Pluschke, Elisabeth Reus, Matthias Rottmann, Jürg Utzinger, Louisa Warryn, Sergio Wittlin, Jennifer Keiser. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Background: Zanzibar has made substantial progress in malaria control with vector control, improved diagnosis, and artemisinin-based combination therapy. Parasite prevalence in the population has remained around 1% but imported infections from mainland Tanzania contribute to sustained local transmission. Understanding travel patterns between mainland Tanzania and Zanzibar, and the risk of malaria infection, may help to control malaria importation to Zanzibar., Methods: A rolling cross-sectional survey linked to routine reactive case detection of malaria was carried out in Zanzibar between May 2017 and October 2018. Households of patients diagnosed with malaria at health facilities were surveyed and household members were tested for malaria using rapid diagnostic tests and a sub-sample by quantitative PCR (qPCR). Interviews elicited a detailed travel history of all household members who had travelled within the past two months, including trips within and outside of Zanzibar. We estimated the association of malaria infection with travel destinations in pre-defined malaria endemicity categories, trip duration, and other co-variates using logistic regression., Results: Of 17,891 survey participants, 1177 (7%) reported a recent trip, of which 769 (65%) visited mainland Tanzania. Among travellers to mainland Tanzania with travel destination details and a qPCR result available, 241/378 (64%) reported traveling to districts with a 'high' malaria endemicity and for 12% the highest endemicity category was 'moderate'. Travelers to the mainland were more likely to be infected with malaria parasites (29%, 108/378) than those traveling within Zanzibar (8%, 16/206) or to other countries (6%, 2/17). Among travellers to mainland Tanzania, those visiting highly endemic districts had a higher odds of being qPCR-positive than those who travelled only to districts where malaria-endemicity was classified as low or very low (adjusted odd ratio = 7.0, 95% confidence interval: 1.9-25.5). Among travellers to the mainland, 110/378 (29%) never or only sometimes used a mosquito net during their travel., Conclusions: Strategies to reduce malaria importation to Zanzibar may benefit from identifying population groups traveling to highly endemic areas in mainland Tanzania. Targeted interventions to prevent and clear infections in these groups may be more feasible than attempting to screen and treat all travellers upon arrival in Zanzibar., (© 2023. National Institute of Parasitic Diseases.)

Community health workers (CHW) usually refer children with suspected severe malaria to the nearest public health facility or a designated public referral health facility (RHF). Caregivers do not always follow this recommendation. This study aimed at identifying post-referral treatment-seeking pathways that lead to appropriate antimalarial treatment for children less than five years with suspected severe malaria. An observational study in Uganda enrolled children below five years presenting to CHWs with signs of severe malaria. Children were followed up 28 days after enrolment to assess their condition and treatment-seeking history, including referral advice and provision of antimalarial treatment from visited providers. Of 2211 children included in the analysis, 96% visited a second provider after attending a CHW. The majority of CHWs recommended caregivers to take their child to a designated RHF (65%); however, only 59% followed this recommendation. Many children were brought to a private clinic (33%), even though CHWs rarely recommended this type of provider (3%). Children who were brought to a private clinic were more likely to receive an injection than children brought to a RHF (78% vs 51%, p<0.001) and more likely to receive the second or third-line injectable antimalarial (artemether: 22% vs. 2%, p<0.001, quinine: 12% vs. 3%, p<0.001). Children who only went to non-RHF providers were less likely to receive an artemisinin-based combination therapy (ACT) than children who attended a RHF (odds ratio [OR] = 0.64, 95% CI 0.51-0.79, p<0.001). Children who did not go to any provider after seeing a CHW were the least likely to receive an ACT (OR = 0.21, 95% CI 0.14-0.34, p<0.001). Health policies should recognise local treatment-seeking practices and ensure adequate quality of care at the various public and private sector providers where caregivers of children with suspected severe malaria actually seek care., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Brunner et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Zanzibar has made significant progress toward malaria elimination, but recent stagnation requires novel approaches. We developed a highly multiplexed droplet digital PCR (ddPCR)-based amplicon sequencing method targeting 35 microhaplotypes and drug-resistance loci, and successfully sequenced 290 samples from five districts covering both main islands. Here, we elucidate fine-scale Plasmodium falciparum population structure and infer relatedness and connectivity of infections using an identity-by-descent (IBD) approach. Despite high genetic diversity, we observe pronounced fine-scale spatial and temporal parasite genetic structure. Clusters of near-clonal infections on Pemba indicate persistent local transmission with limited parasite importation, presenting an opportunity for local elimination efforts. Furthermore, we observe an admixed parasite population on Unguja and detect a substantial fraction (2.9%) of significantly related infection pairs between Zanzibar and the mainland, suggesting recent importation. Our study provides a high-resolution view of parasite genetic structure across the Zanzibar archipelago and provides actionable insights for prioritizing malaria elimination efforts., (© 2023. The Author(s).)

Pre-referral rectal artesunate suppositories can save the lives of children with severe malaria if patients receive adequate post-referral care. A multi-country randomised controlled trial reporting on the efficacy of rectal artesunate informed the current WHO guidelines. In October, 2022, we reported on the findings of the Community Access to Rectal Artesunate for Malaria (CARAMAL) project, a carefully monitored roll-out of quality-assured rectal artesunate into established community-based health-care systems in DR Congo, Nigeria, and Uganda. The aim of the project was to understand the challenges involved in the successful real-world implementation of pre-referral rectal artesunate and to inform subsequent scale-up in endemic countries. In our study, we found that children treated with pre-referral rectal artesunate in routine clinical practice did not have an increased chance of survival, most likely explained by shortfalls along the continuum of care. A substantial proportion of the more than 6200 severely ill children that were followed up 28 days after treatment initiation did not receive comprehensive severe malaria care, either due to an incomplete referral to a secondary facility, or due to incomplete post-referral treatment. The observational study design allowed for a realistic assessment of the obstacles involved in implementing pre-referral rectal artesunate in settings where malaria mortality remains high. Without improving the entire continuum of care, children will continue to die from severe malaria and promising interventions will fail to meet their full potential., Competing Interests: Declaration of interests We declare no competing interests., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Malaria cases can be classified as imported, introduced or indigenous cases. The World Health Organization's definition of malaria elimination requires an area to demonstrate that no new indigenous cases have occurred in the last three years. Here, we present a stochastic metapopulation model of malaria transmission that distinguishes between imported, introduced and indigenous cases, and can be used to test the impact of new interventions in a setting with low transmission and ongoing case importation. We use human movement and malaria prevalence data from Zanzibar, Tanzania, to parameterise the model. We test increasing the coverage of interventions such as reactive case detection; implementing new interventions including reactive drug administration and treatment of infected travellers; and consider the potential impact of a reduction in transmission on Zanzibar and mainland Tanzania. We find that the majority of new cases on both major islands of Zanzibar are indigenous cases, despite high case importation rates. Combinations of interventions that increase the number of infections treated through reactive case detection or reactive drug administration can lead to substantial decreases in malaria incidence, but for elimination within the next 40 years, transmission reduction in both Zanzibar and mainland Tanzania is necessary., (© 2023. The Author(s).)

Severe malaria is a potentially fatal condition that requires urgent treatment. In a clinical trial, a sub-group of children treated with rectal artesunate (RAS) before being referred to a health facility had an increased chance of survival. We recently published in BMC Medicine results of the CARAMAL Project that did not find the same protective effect of pre-referral RAS implemented at scale under real-world conditions in three African countries. Instead, CARAMAL identified serious health system shortfalls that impacted the entire continuum of care, constraining the effectiveness of RAS. Correspondence to the article criticized the observational study design and the alleged interpretation and consequences of our findings.Here, we clarify that we do not dispute the life-saving potential of RAS, and discuss the methodological criticism. We acknowledge the potential for confounding in observational studies. Nevertheless, the totality of CARAMAL evidence is in full support of our conclusion that the conditions under which RAS can be beneficial were not met in our settings, as children often failed to complete referral and post-referral treatment was inadequate.The criticism did not appear to acknowledge the realities of highly malarious settings documented in detail in the CARAMAL project. Suggesting that trial-demonstrated efficacy is sufficient to warrant large-scale deployment of pre-referral RAS ignores the paramount importance of functioning health systems for its delivery, for completing post-referral treatment, and for achieving complete cure. Presenting RAS as a "magic bullet" distracts from the most urgent priority: fixing health systems so they can provide a functioning continuum of care and save the lives of sick children.The data underlying our publication is freely accessible on Zenodo., (© 2023. The Author(s).)

Background: For a full treatment course of severe malaria, community-administered pre-referral rectal artesunate (RAS) should be completed by post-referral treatment consisting of an injectable antimalarial and oral artemisinin-based combination therapy (ACT). This study aimed to assess compliance with this treatment recommendation in children under 5 years., Methods and Findings: This observational study accompanied the implementation of RAS in the Democratic Republic of the Congo (DRC), Nigeria, and Uganda between 2018 and 2020. Antimalarial treatment was assessed during admission in included referral health facilities (RHFs) in children under 5 with a diagnosis of severe malaria. Children were either referred from a community-based provider or directly attending the RHF. RHF data of 7,983 children was analysed for appropriateness of antimalarials; a subsample of 3,449 children was assessed additionally for dosage and method of ACT provision (treatment compliance). A parenteral antimalarial and an ACT were administered to 2.7% (28/1,051) of admitted children in Nigeria, 44.5% (1,211/2,724) in Uganda, and 50.3% (2,117/4,208) in DRC. Children receiving RAS from a community-based provider were more likely to be administered post-referral medication according to the guidelines in DRC (adjusted odds ratio (aOR) = 2.13, 95% CI 1.55 to 2.92, P < 0.001), but less likely in Uganda (aOR = 0.37, 95% CI 0.14 to 0.96, P = 0.04) adjusting for patient, provider, caregiver, and other contextual factors. While in DRC, inpatient ACT administration was common, ACTs were often prescribed at discharge in Nigeria (54.4%, 229/421) and Uganda (53.0%, 715/1,349). Study limitations include the unfeasibility to independently confirm the diagnosis of severe malaria due to the observational nature of the study., Conclusions: Directly observed treatment was often incomplete, bearing a high risk for partial parasite clearance and disease recrudescence. Parenteral artesunate not followed up with oral ACT constitutes an artemisinin monotherapy and may favour the selection of resistant parasites. In connection with the finding that pre-referral RAS had no beneficial effect on child survival in the 3 study countries, concerns about an effective continuum of care for children with severe malaria seem justified. Stricter compliance with the WHO severe malaria treatment guidelines is critical to effectively manage this disease and further reduce child mortality., Trial Registration: ClinicalTrials.gov (NCT03568344)., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Signorell et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: Rectal artesunate, an efficacious pre-referral treatment for severe malaria in children, was deployed at scale in Uganda, Nigeria, and DR Congo. In addition to distributing rectal artesunate, implementation required additional investments in crucial but neglected components in the care for severe malaria. We examined the real-world costs and constraints to rectal artesunate implementation., Methods: We collected primary data on baseline health system constraints and subsequent rectal artesunate implementation expenditures. We calculated the equivalent annual cost of rectal artesunate implementation per child younger than 5 years at risk of severe malaria, from a health system perspective, separating neglected routine health system components from incremental costs of rectal artesunate introduction., Findings: The largest baseline constraints were irregular health worker supervisions, inadequate referral facility worker training, and inadequate malaria commodity supplies. Health worker training and behaviour change campaigns were the largest startup costs, while supervision and supply chain management accounted for most annual routine costs. The equivalent annual costs of preparing the health system for managing severe malaria with rectal artesunate were US$2·63, $2·20, and $4·19 per child at risk and $322, $219, and $464 per child treated in Uganda, Nigeria, and DR Congo, respectively. Strengthening the neglected, routine health system components accounted for the majority of these costs at 71·5%, 65·4%, and 76·4% of per-child costs, respectively. Incremental rectal artesunate costs accounted for the minority remainder., Interpretation: Although rectal artesunate has been touted as a cost-effective pre-referral treatment for severe malaria in children, its real-world potential is limited by weak and under-financed health system components. Scaling up rectal artesunate or other interventions relying on community health-care providers only makes sense alongside additional, essential health system investments sustained over the long term., Funding: Unitaid., Translation: For the French translation of the abstract see Supplementary Materials section., Competing Interests: Declaration of interests All authors had financial support from Unitaid for the submitted work., (Copyright © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Malaria persists at low levels on Zanzibar despite the use of vector control and case management. We use a metapopulation model to investigate the role of human mobility in malaria persistence on Zanzibar, and the impact of reactive case detection. The model was parameterized using survey data on malaria prevalence, reactive case detection, and travel history. We find that in the absence of imported cases from mainland Tanzania, malaria would likely cease to persist on Zanzibar. We also investigate potential intervention scenarios that may lead to elimination, especially through changes to reactive case detection. While we find that some additional cases are removed by reactive case detection, a large proportion of cases are missed due to many infections having a low parasite density that go undetected by rapid diagnostic tests, a low rate of those infected with malaria seeking treatment, and a low rate of follow up at the household level of malaria cases detected at health facilities. While improvements in reactive case detection would lead to a reduction in malaria prevalence, none of the intervention scenarios tested here were sufficient to reach elimination. Imported cases need to be treated to have a substantial impact on prevalence., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier B.V. All rights reserved.)

Malaria risk in Papua New Guinea (PNG) is highly heterogeneous, between and within geographical regions, which is operationally challenging for control. To enhance targeting of malaria interventions in PNG, we investigated risk factors and stratified malaria incidence at the level of health facility catchment areas. Catchment areas and populations of 808 health facilities were delineated using a travel-time accessibility approach and linked to reported malaria cases (2011-2019). Zonal statistics tools were used to calculate average altitude and air temperature in catchment areas before they were spatially joined with incidence rates. In addition, empirical Bayesian kriging (EBK) was employed to interpolate incidence risk strata across PNG. Malaria annual incidence rates are, on average, 186.3 per 1000 population in catchment areas up to 600 m, dropped to 98.8 at (800-1400) m, and to 24.1 cases above 1400 m altitude. In areas above the two altitudinal thresholds 600m and 1400m, the average annual temperature drops below 22°C and 17°C, respectively. EBK models show very low- to low-risk strata (<100 cases per 1000) in the Highlands, National Capital District and Bougainville. In contrast, patches of high-risk (>200 per 1000) strata are modelled mainly in Momase and Islands Regions. Besides, strata with moderate risk (100-200) predominate throughout the coastal areas. While 35.7% of the PNG population (estimated 3.33 million in 2019) lives in places at high or moderate risk of malaria, 52.2% (estimated 4.88 million) resides in very low-risk areas. In five provinces, relatively large proportions of populations (> 50%) inhabit high-risk areas: New Ireland, East and West New Britain, Sandaun and Milne Bay. Incidence maps show a contrast in malaria risk between coastal and inland areas influenced by altitude. However, the risk is highly variable in low-lying areas. Malaria interventions should be guided by sub-national risk levels in PNG., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2022 Seidahmed et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Background: For children below 6 years with suspected severe malaria attending a health care provider unable to provide parenteral malaria treatment, pre-referral rectal artesunate (RAS) is recommended by the World Health Organization to prevent death and disability. A number of African countries are in the process of rolling out quality-assured RAS for pre-referral treatment of severe malaria at community-level. The success of RAS depends, among other factors, on the acceptability of RAS in the communities where it is being rolled-out. Yet to date, there is limited literature on RAS acceptability. This study aimed to determine the acceptability of RAS by health care providers and child caregivers in communities where quality assured RAS was rolled out. This study was nested within the comprehensive multi-country observational research project Community Access to Rectal Artesunate for Malaria (CARAMAL), implemented in the Democratic Republic of the Congo (DRC), Nigeria, and Uganda between 2018 and 2020. Data from three different sources were analysed to understand RAS acceptability: interviews with health workers during three health care provider surveys (N = 341 community health workers and 467 primary health facility workers), with caregivers of children < 5 years of age during three household surveys (N = 9332 caregivers), and with caregivers of children < 5 years of age who were treated with RAS and enrolled in the CARAMAL Patient Surveillance System (N = 3645 caregivers)., Results: RAS acceptability was high among all interviewed stakeholders in the three countries. After the roll-out of RAS, 97-100% heath care providers in DRC, 98-100% in Nigeria and 93-100% in Uganda considered RAS as very good or good. Majority of caregivers whose children had received RAS for pre-referral management of severe malaria indicated that they would want to get the medication again, if their child had the same illness (99.8% of caregivers in DRC, 100% in Nigeria and 99.9% in Uganda). In three household surveys, 67-80% of caregivers whose children had not previously received RAS considered the medication as useful., Conclusion: RAS was well accepted by health workers and child caregivers in DRC, Nigeria and Uganda. Acceptability is unlikely to be an obstacle to the large-scale roll-out of RAS in the studied settings., (© 2022. The Author(s).)

The research and control of malaria has a long history in Papua New Guinea, sometimes resulting in substantial changes to the distribution of infection and transmission dynamics in the country. There have been four major periods of malaria control in PNG, with the current control programme having commenced in 2004. Each previous control programme was successful in reducing malaria burden in the country, but multiple factors led to programme failures and eventual breakdown. A comprehensive review of the literature dating from 1900 to 2021 was undertaken to summarize control strategies, epidemiology, vector ecology and environmental drivers of malaria transmission in PNG. Evaluations of historical control programs reveal poor planning and communication, and difficulty in sustaining financial investment once malaria burden had decreased as common themes in the breakdown of previous programs. Success of current and future malaria control programs in PNG is contingent on adequate planning and management of control programs, effective communication and engagement with at-risk populations, and cohesive targeted approaches to sub-national and national control and elimination., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Cleary, Hetzel and Clements.)

Background: To prevent child deaths from severe malaria, early parenteral treatment is essential. Yet, in remote rural areas, accessing facilities offering parenteral antimalarials may be difficult. A randomised controlled trial found pre-referral treatment with rectal artesunate (RAS) to reduce deaths and disability in children who arrived at a referral facility with delay. This study examined the effectiveness of pre-referral RAS treatment implemented through routine procedures of established community-based health care systems., Methods: An observational study accompanied the roll-out of RAS in the Democratic Republic of the Congo (DRC), Nigeria and Uganda. Children <5 years of age presenting to a community-based health provider with a positive malaria test and signs of severe malaria were enrolled and followed up during admission and after 28 days to assess their health status and treatment history. The primary outcome was death; covariates of interest included RAS use, referral completion, and post-referral treatment., Results: Post-roll-out, RAS was administered to 88% of patients in DRC, 52% in Nigeria, and 70% in Uganda. The overall case fatality rate (CFR) was 6.7% (135/2011) in DRC, 11.7% (69/589) in Nigeria, and 0.5% (19/3686) in Uganda; 13.8% (865/6286) of patients were sick on day 28. The CFR was higher after RAS roll-out in Nigeria (16.1 vs. 4.2%) and stable in DRC (6.7 vs. 6.6%) and Uganda (0.7 vs. 0.3%). In DRC and Nigeria, children receiving RAS were more likely to die than those not receiving RAS (aOR=3.06, 95% CI 1.35-6.92 and aOR=2.16, 95% CI 1.11-4.21, respectively). Only in Uganda, RAS users were less likely to be dead or sick at follow-up (aOR=0.60, 95% CI 0.45-0.79). Post-referral parenteral antimalarials plus oral artemisinin-based combination therapy (ACT), a proxy for appropriate post-referral treatment, was protective. However, in referral health facilities, ACT was not consistently administered after parenteral treatment (DRC 68.4%, Nigeria 0%, Uganda 70.9%)., Conclusions: Implemented at scale to the recommended target group, pre-referral RAS had no beneficial effect on child survival in three highly malaria-endemic settings. RAS is unlikely to reduce malaria deaths unless health system issues such as referral and quality of care at all levels are addressed., Trial Registration: The study is registered on ClinicalTrials.gov : NCT03568344., (© 2022. The Author(s).)

The key to reducing malaria deaths in highly endemic areas is prompt access to quality case management. Given that many severe cases occur at peripheral level, rectal artesunate (RAS) in the form of suppositories was developed in the 1990s, allowing for rapid initiation of life-saving antimalarial treatment before referral to a health facility with full case management capabilities. One randomized controlled trial published in 2009 showed a protective effect of RAS pre-referral treatment against overall mortality of 26%, but with significant differences according to study sites and length of referral. Two important issues remained unaddressed: (1) whether the mortality impact of RAS observed under controlled trial conditions could be replicated under real-world circumstances; and (2) clear operational guidance for the wide-scale implementation of RAS, including essential health system determinants for optimal impact. From 2018 to 2020, the Community Access to Rectal Artesunate for Malaria (CARAMAL) project was conducted as a large-scale observational implementation study in the Democratic Republic of the Congo (DRC), Nigeria, and Uganda (registered on ClinicalTrials.gov as NCT03568344). CARAMAL aimed to provide high-quality field evidence on the two issues above, in three remote settings with high malaria endemicity. A number of complementary study components were implemented. The core of the CARAMAL study was the Patient Surveillance System (PSS), which allowed tracking of cases of severe febrile illness from first contact at the periphery to a referral health facility, and then on to a Day 28 visit at the home of the patient. Community and provider cross-sectional surveys complemented the PSS. Here we describe in some detail RAS implementation, as well as the key CARAMAL study components and basic implementation experience. This manuscript does not intend to present key study results, but provides an extensive reference document for the companion papers describing the impact, referral process, post-referral treatment and costing of the RAS intervention., Competing Interests: Authors EO, BA, KA, CO, and OY are employees of Akena Associates. There are no patents, products in development or marketed products to declare. This does not alter our adherence to PLOS ONE policies on sharing data and materials. None of the authors have any competing interests in the topic presented in this manuscript., (Copyright: © 2022 Lengeler et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Identification, stabilization, and prompt referral of children with signs of severe febrile disease (danger signs) in rural communities are crucial for preventing complications and death from severe malaria, pneumonia, and diarrhea. We set out to determine the treatment-seeking practices and treatment patterns for children < 5 years of age with an acute febrile illness, with or without danger signs of severe disease, in a highly malaria-endemic area of northern Uganda. Three household surveys were conducted from November through December each year in 2018, 2019, and 2020. Overall, 30% of the children in the study were reported to have had a WHO-classified danger sign including convulsions, unconsciousness/unusually sleepy, inability to feed or drink, and vomiting everything. Only half of the children in this study sought care from a health provider. However, significantly more children with danger signs of severe disease sought and received treatment and diagnostics from a health provider, compared with those without danger signs (adjusted odds ratio: 1.6, 95% confidence interval: 1.2-2.0; P < 0.01). In the total population studied, care seeking in the public sector was 26% and similar to care seeking in the private sector (24%). Community health workers were used as the first source of care by 12% of the children. Approximately 38% of the children who were reported to have danger signs of severe disease requiring prompt referral and treatment did not seek care from a health provider. Understanding and addressing barriers to accessing healthcare could contribute to better treatment seeking practices.

Most rapid diagnostic tests for Plasmodium falciparum malaria target the Histidine-Rich Proteins 2 and 3 (HRP2 and HRP3). Deletions of the hrp2 and hrp3 genes result in false-negative tests and are a threat for malaria control. A novel assay for molecular surveillance of hrp2 / hrp3 deletions was developed based on droplet digital PCR (ddPCR). The assay quantifies hrp2 , hrp3 , and a control gene with very high accuracy. The theoretical limit of detection was 0.33 parasites/µl. The deletion was reliably detected in mixed infections with wild-type and hrp2 -deleted parasites at a density of >100 parasites/reaction. For a side-by-side comparison with the conventional nested PCR (nPCR) assay, 248 samples were screened in triplicate by ddPCR and nPCR. No deletions were observed by ddPCR, while by nPCR hrp2 deletion was observed in 8% of samples. The ddPCR assay was applied to screen 830 samples from Kenya, Zanzibar/Tanzania, Ghana, Ethiopia, Brazil, and Ecuador. Pronounced differences in the prevalence of deletions were observed among sites, with more hrp3 than hrp2 deletions. In conclusion, the novel ddPCR assay minimizes the risk of false-negative results (i.e., hrp2 deletion observed when the sample is wild type), increases sensitivity, and greatly reduces the number of reactions that need to be run., Competing Interests: CV, AH, CO, KB, MA, JY, MH, BF, AA, MF, SL, FS, YA, EZ, DY, JK, GY, CK No competing interests declared, (© 2022, Vera-Arias et al.)

Background: Vector mosquito biting intensity is an important measure to understand malaria transmission. Human landing catch (HLC) is an effective but labour-intensive, expensive, and potentially hazardous entomological surveillance tool. The Centres for Disease Control light trap (CDC-LT) and the human decoy trap (HDT) are exposure-free alternatives. This study compared the CDC-LT and HDT against HLC for measuring Anopheles biting in rural Tanzania and assessed their suitability as HLC proxies., Methods: Indoor mosquito surveys using HLC and CDC-LT and outdoor surveys using HLC and HDT were conducted in 2017 and in 2019 in Ulanga, Tanzania in 19 villages, with one trap/house/night. Species composition, sporozoite rates and density/trap/night were compared. Aggregating the data by village and month, the Bland-Altman approach was used to assess agreement between trap types., Results: Overall, 66,807 Anopheles funestus and 14,606 Anopheles arabiensis adult females were caught with 6,013 CDC-LT, 339 indoor-HLC, 136 HDT and 195 outdoor-HLC collections. Indoors, CDC-LT caught fewer An. arabiensis (Adjusted rate ratio [Adj.RR] = 0.35, 95% confidence interval [CI]: 0.27-0.46, p < 0.001) and An. funestus (Adj.RR = 0.63, 95%CI: 0.51-0.79, p < 0.001) than HLC per trap/night. Outdoors, HDT caught fewer An. arabiensis (Adj.RR = 0.04, 95%CI: 0.01-0.14, p < 0.001) and An. funestus (Adj.RR = 0.10, 95%CI: 0.07-0.15, p < 0.001) than HLC. The bias and variability in number of mosquitoes caught by the different traps were dependent on mosquito densities. The relative efficacies of both CDC-LT and HDT in comparison to HLC declined with increased mosquito abundance. The variability in the ratios was substantial for low HLC counts and decreased as mosquito abundance increased. The numbers of sporozoite positive mosquitoes were low for all traps., Conclusions: CDC-LT can be suitable for comparing mosquito populations between study arms or over time if accuracy in the absolute biting rate, compared to HLC, is not required. CDC-LT is useful for estimating sporozoite rates because large numbers of traps can be deployed to collect adequate mosquito samples. The present design of the HDT is not amenable for use in large-scale entomological surveys. Use of HLC remains important for estimating human exposure to mosquitoes as part of estimating the entomological inoculation rate (EIR)., (© 2022. The Author(s).)

Introduction: Children who receive prereferral rectal artesunate (RAS) require urgent referral to a health facility where appropriate treatment for severe malaria can be provided. However, the rapid improvement of a child's condition after RAS administration may influence a caregiver's decision to follow this recommendation. Currently, the evidence on the effect of RAS on referral completion is limited., Methods: An observational study accompanied the roll-out of RAS in three malaria endemic settings in the Democratic Republic of the Congo (DRC), Nigeria and Uganda. Community health workers and primary health centres enrolled children under 5 years with suspected severe malaria before and after the roll-out of RAS. All children were followed up 28 days after enrolment to assess their treatment-seeking pathways., Results: Referral completion was 67% (1408/2104) in DRC, 48% (287/600) in Nigeria and 58% (2170/3745) in Uganda. In DRC and Uganda, RAS users were less likely to complete referral than RAS non-users in the pre-roll-out phase (adjusted OR (aOR)=0.48, 95% CI 0.30 to 0.77 and aOR=0.72, 95% CI 0.58 to 0.88, respectively). Among children seeking care from a primary health centre in Nigeria, RAS users were less likely to complete referral compared with RAS non-users in the post-roll-out phase (aOR=0.18, 95% CI 0.05 to 0.71). In Uganda, among children who completed referral, RAS users were significantly more likely to complete referral on time than RAS non-users enrolled in the pre-roll-out phase (aOR=1.81, 95% CI 1.17 to 2.79)., Conclusions: The findings of this study raise legitimate concerns that the roll-out of RAS may lead to lower referral completion in children who were administered prereferral RAS. To ensure that community-based programmes are effectively implemented, barriers to referral completion need to be addressed at all levels. Alternative effective treatment options should be provided to children unable to complete referral., Trial Registrstion Number: NCT03568344; ClinicalTrials.gov., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: A malaria control programme based on distribution of long-lasting insecticidal bed nets (LLINs) and artemisinin combination therapy began in Papua New Guinea in 2009. After implementation of the programme, substantial reductions in vector abundance and malaria transmission intensity occurred. The research reported here investigated whether these reductions remained after seven years of sustained effort., Methods: All-night (18:00 to 06:00) mosquito collections were conducted using human landing catches and barrier screen methods in four villages of Madang Province between September 2016 and March 2017. Anopheles species identification and sporozoite infection with Plasmodium vivax and Plasmodium falciparum were determined with molecular methods. Vector composition was expressed as the relative proportion of different species in villages, and vector abundance was quantified as the number of mosquitoes per barrier screen-night and per person-night. Transmission intensity was quantified as the number of sporozoite-infective vector bites per person-night., Results: Five Anopheles species were present, but vector composition varied greatly among villages. Anopheles koliensis, a strongly anthropophilic species was the most prevalent in Bulal, Matukar and Wasab villages, constituting 63.7-73.8% of all Anopheles, but in Megiar Anopheles farauti was the most prevalent species (97.6%). Vector abundance varied among villages (ranging from 2.8 to 72.3 Anopheles per screen-night and 2.2-31.1 Anopheles per person-night), and spatially within villages. Malaria transmission intensity varied among the villages, with values ranging from 0.03 to 0.5 infective Anopheles bites per person-night. Most (54.1-75.1%) of the Anopheles bites occurred outdoors, with a substantial proportion (25.5-50.8%) occurring before 22:00., Conclusion: The estimates of vector abundance and transmission intensity in the current study were comparable to or higher than estimates in the same villages in 2010-2012, indicating impeded programme effectiveness. Outdoor and early biting behaviours of vectors are some of the likely explanatory factors. Heterogeneity in vector composition, abundance and distribution among and within villages challenge malaria control programmes and must be considered when planning them., (© 2021. The Author(s).)