Mass drug administration can be a valuable addition to the malaria elimination toolbox

No secondary impact of ivermectin mass drug administration for onchocerciasis elimination on the prevalence of scabies in northwestern Ethiopia

BACKGROUND

Mass drug administration (MDA) is among the five major strategies that are currently in use to control, eliminate or eradicate Neglected Tropical Diseases (NTDs). Optimising MDA to control multiple NTDs maximises impact. The objective of this study is to estimate the secondary impact of ivermectin MDA for onchocerciasis on the prevalence of scabies.

METHODS

This quasi-experimental study was conducted in Ayu Guagusa district, northwestern Ethiopia. Scabies prevalence was estimated in surveys before the MDA, at 6 and 12 months afterwards. The sample size was 1437 people from a panel of 381 randomly selected study households. Multistage sampling was employed in randomly selecting six kebeles (the lowest administrative unit) with respective gotes (small villages) and households. All members of the selected households were invited to participate in the study and participants who were available in all three surveys formed a cohort.

RESULTS

Scabies prevalence was similar prior to the MDA (13.4%, 95% CI 11.7 to 15.2%) and 6 months after (11.7%, 95% CI 10.1 to 13.2%) but was substantially greater at 12 months (22.1%, 95% CI 20.1 to 24.1%). The 6-month incidence and disappearance rates were 10.8% (95% CI 8.8 to 13.2%) and 82.6% (95% CI 75.0 to 88.6%), respectively.

CONCLUSIONS

Ivermectin MDA for onchocerciasis was not observed to have a secondary impact on the prevalence of scabies over the follow-up period of 12 months.

Assessing the acceptability and feasibility of reactive drug administration for malaria elimination in a Plasmodium vivax predominant setting: a qualitative study in two provinces in Thailand

BACKGROUND

Reactive case detection (RACD) or testing and treatment of close contacts of recent malaria cases, is commonly practiced in settings approaching malaria elimination, but standard diagnostics have limited sensitivity to detect low level infections. Reactive drug administration (RDA), or presumptive treatment without testing, is an alternative approach, but better understanding regarding community acceptability and operational feasibility are needed.

METHODS

A qualitative study was conducted as part of a two-arm cluster randomized-controlled trial evaluating the effectiveness of RDA targeting high-risk villages and forest workers for reducing Plasmodium vivax and P. falciparum malaria in Thailand. Key informant interviews (KIIs) and focus group discussions (FGDs) were conducted virtually among key public health staff, village health volunteers (VHVs), and household members that implemented or received RDA activities. Transcriptions were reviewed, coded, and managed manually using Dedoose qualitative data analysis software, then underwent qualitative content analysis to identify key themes.

RESULTS

RDA was well accepted by household members and public health staff that implemented it. RDA participation was driven by fear of contracting malaria, eagerness to receive protection provided by malaria medicines, and the increased access to health care. Concerns were raised about the safety of taking malaria medicines without having an illness, particularly if underlying health conditions existed. Health promotion hospital (HPH) staff implementing RDA noted its operational feasibility, but highlighted difficulty in traveling to remote areas, and requested additional travel resources and hiring more VHVs. Other challenges were highlighted including the need for additional training for VHVs on malaria activities and the inability of HPH staff to conduct RDA due to other health priorities (e.g., Covid-19). More training and practice for VHVs were noted as ways to improve implementation of RDA.

CONCLUSIONS

To maximize uptake of RDA, regular education and sensitization campaigns in collaboration with village leaders on the purpose and rationale of RDA will be critical. To alleviate safety concerns and increase participant safety, a rigorous pharmacovigilance program will be important. To accelerate uptake of RDA, trust between HPH staff and VHVs and the communities they serve must continue to be strengthened to ensure acceptance of the intervention.

TRIAL REGISTRATION

This study was approved by the Committee on Human Research at the University of California San Francisco (19-28,060) and the local Ethics Committee for Research in Human Subjects at Tak Provincial Health office (009/63) and Kanchanaburi Provincial health office (Kor Chor 0032.002/2185). Local authorities and health officers in the provinces, districts, and villages agreed upon and coordinated the implementation of the study. All methods in this study were carried out in accordance with relevant guidelines and regulations.

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.

Malaria Control by Mass Drug Administration With Artemisinin Plus Piperaquine on Grande Comore Island, Union of Comoros

Background

Mass drug administration (MDA) is a powerful tool for malaria control, but the medicines to use, dosing, number of rounds, and potential selection of drug resistance remain open questions.

Methods

Two monthly rounds of artemisinin-piperaquine (AP), each comprising 2 daily doses, were administered across the 7 districts of Grande Comore Island. In 3 districts, low-dose primaquine (PMQ_LD) was also given on the first day of each monthly round. Plasmodium falciparum malaria rates, mortality, parasitemias, adverse events, and genetic markers of potential drug resistance were evaluated.

Results

Average population coverages of 80%-82% were achieved with AP in 4 districts (registered population 258 986) and AP + PMQ_LD in 3 districts (83 696). The effectiveness of MDA was 96.27% (95% confidence interval [CI], 95.27%-97.06%; P < .00001) in the 4 AP districts and 97.46% (95% CI, 94.54%-98.82%; P < .00001) in the 3 AP + PMQ_LD districts. In comparative statistical modeling, the effectiveness of the 2 monthly rounds on Grande Comore Island was nearly as high as that of 3 monthly rounds of AP or AP + PMQ_LD in our earlier study on Anjouan Island. Surveys of pre-MDA and post-MDA samples showed no significant changes in PfK13 polymorphism rates, and no PfCRT mutations previously linked to piperaquine resistance in Southeast Asia were identified.

Conclusions

MDA with 2 monthly rounds of 2 daily doses of AP was highly effective on Grande Comore Island. The feasibility and lower expense of this 2-month versus 3-month regimen of AP may offer advantages for MDA programs in appropriate settings.

Impact of population based indoor residual spraying with and without mass drug administration with dihydroartemisinin-piperaquine on malaria prevalence in a high transmission setting: a quasi-experimental controlled before-and-after trial in northeastern Uganda

BACKGROUND

Declines in malaria burden in Uganda have slowed. Modelling predicts that indoor residual spraying (IRS) and mass drug administration (MDA), when co-timed, have synergistic impact. This study investigated additional protective impact of population-based MDA on malaria prevalence, if any, when added to IRS, as compared with IRS alone and with standard of care (SOC).

METHODS

The 32-month quasi-experimental controlled before-and-after trial enrolled an open cohort of residents (46,765 individuals, 1st enumeration and 52,133, 4th enumeration) of Katakwi District in northeastern Uganda. Consented participants were assigned to three arms based on residential subcounty at study start: MDA+IRS, IRS, SOC. IRS with pirimiphos methyl and MDA with dihydroartemisinin- piperaquine were delivered in 4 co-timed campaign-style rounds 8 months apart. The primary endpoint was population prevalence of malaria, estimated by 6 cross-sectional surveys, starting at baseline and preceding each subsequent round.

RESULTS

Comparing malaria prevalence in MDA+IRS and IRS only arms over all 6 surveys (intention-to-treat analysis), roughly every 6 months post-interventions, a geostatistical model found a significant additional 15.5% (95% confidence interval (CI): [13.7%, 17.5%], Z = 9.6, p = 5e-20) decrease in the adjusted odds ratio (aOR) due to MDA for all ages, a 13.3% reduction in under 5's (95% CI: [10.5%, 16.8%], Z = 4.02, p = 5e-5), and a 10.1% reduction in children 5-15 (95% CI: [8.5%, 11.8%], Z = 4.7, p = 2e-5). All ages residents of the MDA + IRS arm enjoyed an overall 80.1% reduction (95% CI: [80.0%, 83.0%], p = 0.0001) in odds of qPCR confirmed malaria compared with SOC residents. Secondary difference-in-difference analyses comparing surveys at different timepoints to baseline showed aOR (MDA + IRS vs IRS) of qPCR positivity between 0.28 and 0.66 (p < 0.001). Of three serious adverse events, one (nonfatal) was considered related to study medications. Limitations include the initial non-random assignment of study arms, the single large cluster per arm, and the lack of an MDA-only arm, considered to violate equipoise.

CONCLUSIONS

Despite being assessed at long time points 5-7 months post-round, MDA plus IRS provided significant additional protection from malaria infection over IRS alone. Randomized trials of MDA in large areas undergoing IRS recommended as well as cohort studies of impact on incidence.

TRIAL REGISTRATION

This trial was retrospectively registered 11/07/2018 with the Pan African Clinical Trials Registry (PACTR201807166695568).

Simulating the Impacts of Augmenting Intensive Vector Control with Mass Drug Administration or Test-and-Treat Strategies on the Malaria Infectious Reservoir

Highly effective vector control can reduce malaria burden significantly, but individuals with parasitemia provide a potential reservoir for onward transmission. We performed an empirical, non-parametric simulation based on cohort data from Tororo District, Uganda-an area with historically high but recently reduced malaria transmission-to estimate the effects of mass drug administration (MDA) and test-and-treat on parasite prevalence. We estimate that a single round of MDA would have accelerated declines in parasite prevalence dramatically over 2 years (cumulative parasite prevalence ratio [PPR], 0.34). This decline was mostly during the first year of administration (PPR, 0.23) and waned by 23 months (PPR, 0.74). Test-and-treat using a highly sensitive diagnostic had nearly the same effect as MDA at 1 year (PPR, 0.27) and required many fewer treatments. The impact of test-and-treat using a standard diagnostic was modest (PPR, 0.58 at 1 year). Our analysis suggests that in areas experiencing a dramatic reduction in malaria prevalence, MDA or test-and-treat with a highly sensitive diagnostic may be an effective way of reducing or eliminating the infectious reservoir temporarily. However, for sustained benefits, repeated rounds of the intervention or additional interventions are required.

Ethical challenges in mass drug administration for reducing childhood mortality: a qualitative study

Background

Mass drug administration (MDA) of medications to entire at-risk communities or populations has shown promise in the control and elimination of global infectious diseases. MDA of the broad-spectrum antibiotic azithromycin has demonstrated the potential to reduce childhood mortality in children at risk of premature death in some global settings. However, MDA of antibiotics raises complex ethical challenges, including weighing near-term benefits against longer-term risks—particularly the development of antimicrobial resistance that could diminish antibiotic effectiveness for current or future generations. The aim of this study was to understand how key actors involved in MDA perceive the ethical challenges of MDA.

Methods

We conducted 35 semi-structured interviews from December 2020–February 2022 with investigators, funders, bioethicists, research ethics committee members, industry representatives, and others from both high-income countries (HICs) and low- and middle-income countries (LMICs). Interview participants were identified via one of seven MDA studies purposively chosen to represent diversity in terms of use of the antibiotic azithromycin; use of a primary mortality endpoint; and whether the study occurred in a high child mortality country. Data were analyzed using constructivist grounded theory methodology.

Results

The most frequently discussed ethical challenges related to meaningful community engagement, how to weigh risks and benefits, and the need to target MDA We developed a concept map of how participants considered ethical issues in MDA for child mortality; it emphasizes MDA’s place alongside other public health interventions, empowerment, and equity. Concerns over an ethical double standard in weighing risks and benefits emerged as a unifying theme, albeit one that participants interpreted in radically different ways. Some thought MDA for reducing child mortality was ethically obligatory; others suggested it was impermissible.

Conclusions

Ethical challenges raised by MDA of antibiotics for childhood mortality—which span socio-cultural issues, the environment, and effects on future generations—require consideration beyond traditional clinical trial review. The appropriate role of MDA also requires attention to concerns over ethical double standards and power dynamics in global health that affect how we view antibiotic use in HICs versus LMICs. Our findings suggest the need to develop additional, comprehensive guidance on managing ethical challenges in MDA.

Graphical Abstract

Etramp5 as a useful serological marker in children to assess the immediate effects of mass drug campaigns for malaria

INTRODUCTION

Serological methods provide useful metrics to estimate age-specific period prevalence in settings of low malaria transmission; however, evidence on the use of seropositivity as an endpoint remains scarce in studies to evaluate combinations of malaria control measures, especially in children. This study aims to evaluate the immediate effects of a targeted mass drug administration campaign (tMDA) in Haiti by using serological markers.

METHODS

The tMDA was implemented in September-October 2018 using sulfadoxine-pyrimethamine and single low-dose primaquine. A natural quasi-experimental study was designed, using a pretest and posttest in a cohort of 754 randomly selected school children, among which 23% reported having received tMDA. Five antigens were selected as outcomes (MSP1-19, AMA-1, Etramp5 antigen 1, HSP40, and GLURP-R0). Posttest was conducted 2-6 weeks after the intervention.

RESULTS

At baseline, there was no statistical difference in seroprevalence between the groups of children that were or were not exposed during the posttest. A lower seroprevalence was observed for markers informative of recent exposure (Etramp5 antigen 1, HSP40, and GLURP-R0). Exposure to tMDA was significantly associated with a 50% reduction in the odds of seropositivity for Etramp5 antigen 1 and a 21% reduction in the odds of seropositivity for MSP119.

CONCLUSION

Serological markers can be used to evaluate the effects of interventions against malaria on the risk of infection in settings of low transmission. Antibody responses against Etramp5 antigen 1 in Haitian children were reduced in the 2-6 weeks following a tMDA campaign, confirming its usefulness as a short-term marker in child populations.

Environmental impacts of mass drug administration programs: exposures, risks, and mitigation of antimicrobial resistance

Mass drug administration (MDA) of antimicrobials has shown promise in the reduction and potential elimination of a variety of neglected tropical diseases (NTDs). However, with antimicrobial resistance (AMR) becoming a global crisis, the risks posed by widespread antimicrobial use need to be evaluated. As the role of the environment in AMR emergence and dissemination has become increasingly recognized, it is likewise crucial to establish the role of MDA in environmental AMR pollution, along with the potential impacts of such pollution. This review presents the current state of knowledge on the antimicrobial compounds, resistant organisms, and antimicrobial resistance genes in MDA trials, routes of these determinants into the environment, and their persistence and ecological impacts, particularly in low and middle-income countries where these trials are most common. From the few studies directly evaluating AMR outcomes in azithromycin MDA trials, it is becoming apparent that MDA efforts can increase carriage and excretion of resistant pathogens in a lasting way. However, research on these outcomes for other antimicrobials used in MDA trials is sorely needed. Furthermore, while paths of AMR determinants from human waste to the environment and their persistence thereafter are supported by the literature, quantitative information on the scope and likelihood of this is largely absent. We recommend some mitigative approaches that would be valuable to consider in future MDA efforts. This review stands to be a valuable resource for researchers and policymakers seeking to evaluate the impacts of MDA.

It Is Time to Strengthen the Malaria Control Policy of the Democratic Republic of Congo and Include Schools and School-Age Children in Malaria Control Measures

Despite a decade of sustained malaria control, malaria remains a serious public health problem in the Democratic Republic of Congo (DRC). Children under five years of age and school-age children aged 5–15 years remain at high risk of symptomatic and asymptomatic malaria infections. The World Health Organization’s malaria control, elimination, and eradication recommendations are still only partially implemented in DRC. For better malaria control and eventual elimination, the integration of all individuals into the national malaria control programme will strengthen malaria control and elimination strategies in the country. Thus, inclusion of schools and school-age children in DRC malaria control interventions is needed.

How has mass drug administration with dihydroartemisinin-piperaquine impacted molecular markers of drug resistance? A systematic review

The World Health Organization (WHO) recommends surveillance of molecular markers of resistance to anti-malarial drugs. This is particularly important in the case of mass drug administration (MDA), which is endorsed by the WHO in some settings to combat malaria. Dihydroartemisinin-piperaquine (DHA-PPQ) is an artemisinin-based combination therapy which has been used in MDA. This review analyses the impact of MDA with DHA-PPQ on the evolution of molecular markers of drug resistance. The review is split into two parts. Section I reviews the current evidence for different molecular markers of resistance to DHA-PPQ. This includes an overview of the prevalence of these molecular markers in Plasmodium falciparum Whole Genome Sequence data from the MalariaGEN Pf3k project. Section II is a systematic literature review of the impact that MDA with DHA-PPQ has had on the evolution of molecular markers of resistance. This systematic review followed PRISMA guidelines. This review found that despite being a recognised surveillance tool by the WHO, the surveillance of molecular markers of resistance following MDA with DHA-PPQ was not commonly performed. Of the total 96 papers screened for eligibility in this review, only 20 analysed molecular markers of drug resistance. The molecular markers published were also not standardized. Overall, this warrants greater reporting of molecular marker prevalence following MDA implementation. This should include putative pfcrt mutations which have been found to convey resistance to DHA-PPQ in vitro.

Malaria chemoprevention and drug resistance: a review of the literature and policy implications

Chemoprevention strategies reduce malaria disease and death, but the efficacy of anti-malarial drugs used for chemoprevention is perennially threatened by drug resistance. This review examines the current impact of chemoprevention on the emergence and spread of drug resistant malaria, and the impact of drug resistance on the efficacy of each of the chemoprevention strategies currently recommended by the World Health Organization, namely, intermittent preventive treatment in pregnancy (IPTp); intermittent preventive treatment in infants (IPTi); seasonal malaria chemoprevention (SMC); and mass drug administration (MDA) for the reduction of disease burden in emergency situations. While the use of drugs to prevent malaria often results in increased prevalence of genetic mutations associated with resistance, malaria chemoprevention interventions do not inevitably lead to meaningful increases in resistance, and even high rates of resistance do not necessarily impair chemoprevention efficacy. At the same time, it can reasonably be anticipated that, over time, as drugs are widely used, resistance will generally increase and efficacy will eventually be lost. Decisions about whether, where and when chemoprevention strategies should be deployed or changed will continue to need to be made on the basis of imperfect evidence, but practical considerations such as prevalence patterns of resistance markers can help guide policy recommendations.

Deep Learning for Microscopic Examination of Protozoan Parasites

The infectious and parasitic diseases represent a major threat to public health and are among the main causes of morbidity and mortality. The complex and divergent life cycles of parasites present major difficulties associated with the diagnosis of these organisms by microscopic examination. Deep learning has shown extraordinary performance in biomedical image analysis including various parasites diagnosis in the past few years. Here we summarize advances of deep learning in the field of protozoan parasites microscopic examination, focusing on publicly available microscopic image datasets of protozoan parasites. In the end, we summarize the challenges and future trends, which deep learning faces in protozoan parasite diagnosis.

Efficacy, Safety and Tolerability of Pyronaridine-artesunate in Asymptomatic Malaria-infected Individuals: a Randomized Controlled Trial

BACKGROUND

Pyronaridine-artesunate (PA) is a registered artemisinin-based combination therapy, potentially useful for mass drug administration campaigns. However, further data are needed to evaluate its efficacy, safety and tolerability as full or incomplete treatment in asymptomatic Plasmodium falciparum-infected individuals.

METHODS

This phase II, multi-center, open label, randomized clinical trial was conducted in The Gambia and Zambia. Participants with microscopically confirmed asymptomatic P. falciparum infection were randomly assigned (1:1:1) to receive a 3-day, 2-day, or 1-day treatment regimen of PA (180:60 mg), dosed according to bodyweight. The primary efficacy outcome was polymerase chain reaction (PCR)-adjusted adequate parasitological response (APR) at day 28 in the per-protocol population.

RESULTS

A total of 303 participants were randomized. Day 28 PCR-adjusted APR was 100% for both the 3-day (98/98) and 2-day regimens (96/96), and 96.8% (89/94) for the 1-day regimen. Efficacy was maintained at 100% until day 63 for the 3-day and 2-day regimens but declined to 94.4% (84/89) with the 1-day regimen. Adverse event frequency was similar between the 3-day (51.5% [52/101]), 2-day (52.5% [52/99]), and 1-day (54.4% [56/103]) regimens; the majority of adverse events were of grade 1 or 2 severity (85% [136/160]). Asymptomatic, transient increases (>3 times the upper limit of normal) in alanine aminotransferase/aspartate aminotransferase were observed for 6/301 (2.0%) participants.

CONCLUSIONS

PA had high efficacy and good tolerability in asymptomatic P. falciparum-infected individuals, with similar efficacy for the full 3-day and incomplete 2-day regimens. Although good adherence to the 3-day regimen should be encouraged, these results support the further investigation of PA for mass drug administration campaigns.

CLINICAL TRIALS REGISTRATION

NCT03814616.

Transcriptional correlates of malaria in RTS,S/AS01-vaccinated African children: a matched case–control study

Background:

In a phase 3 trial in African infants and children, the RTS,S/AS01 vaccine (GSK) showed moderate efficacy against clinical malaria. We sought to further understand RTS,S/AS01-induced immune responses associated with vaccine protection.

Methods:

Applying the blood transcriptional module (BTM) framework, we characterized the transcriptomic response to RTS,S/AS01 vaccination in antigen-stimulated (and vehicle control) peripheral blood mononuclear cells sampled from a subset of trial participants at baseline and month 3 (1-month post-third dose). Using a matched case–control study design, we evaluated which of these ‘RTS,S/AS01 signature BTMs’ associated with malaria case status in RTS,S/AS01 vaccinees. Antigen-specific T-cell responses were analyzed by flow cytometry. We also performed a cross-study correlates analysis where we assessed the generalizability of our findings across three controlled human malaria infection studies of healthy, malaria-naive adult RTS,S/AS01 recipients.

Results:

RTS,S/AS01 vaccination was associated with downregulation of B-cell and monocyte-related BTMs and upregulation of T-cell-related BTMs, as well as higher month 3 (vs. baseline) circumsporozoite protein-specific CD4⁺ T-cell responses. There were few RTS,S/AS01-associated BTMs whose month 3 levels correlated with malaria risk. In contrast, baseline levels of BTMs associated with dendritic cells and with monocytes (among others) correlated with malaria risk. The baseline dendritic cell- and monocyte-related BTM correlations with malaria risk appeared to generalize to healthy, malaria-naive adults.

Conclusions:

A prevaccination transcriptomic signature associates with malaria in RTS,S/AS01-vaccinated African children, and elements of this signature may be broadly generalizable. The consistent presence of monocyte-related modules suggests that certain monocyte subsets may inhibit protective RTS,S/AS01-induced responses.

Funding:

Funding was obtained from the NIH-NIAID (R01AI095789), NIH-NIAID (U19AI128914), PATH Malaria Vaccine Initiative (MVI), and Ministerio de Economía y Competitividad (Instituto de Salud Carlos III, PI11/00423 and PI14/01422). The RNA-seq project has been funded in whole or in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under grant number U19AI110818 to the Broad Institute. This study was also supported by the Vaccine Statistical Support (Bill and Melinda Gates Foundation award INV-008576/OPP1154739 to R.G.). C.D. was the recipient of a Ramon y Cajal Contract from the Ministerio de Economía y Competitividad (RYC-2008-02631). G.M. was the recipient of a Sara Borrell–ISCIII fellowship (CD010/00156) and work was performed with the support of Department of Health, Catalan Government grant (SLT006/17/00109). This research is part of the ISGlobal’s Program on the Molecular Mechanisms of Malaria which is partially supported by the Fundación Ramón Areces and we acknowledge support from the Spanish Ministry of Science and Innovation through the ‘Centro de Excelencia Severo Ochoa 2019–2023’ Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program.

Historical experiences on mass drug administration for malaria control and elimination, its challenges and China's experience: a narrative review

After decades of efforts, malaria is still a major public health problem in many countries, especially in sub-Saharan Africa. Mass drug administration (MDA) has been one of the interventions used to control malaria. China, the largest and most populous country in the world, has recently achieved malaria elimination with MDA within its strategy. Therefore, knowing the history of the use of MDA, and its advantages and challenges are crucial to better implement MDA as a component of malaria control and elimination strategy. This narrative review focused on the use of MDA from the past to present, the experiences of successful and failed MDA interventions to control malaria in Africa, Asia, and South Pacific region, the challenges faced, as well as China's experience in malaria control and elimination. A direct search using key words and phrases was conducted using the web search engines Google and Google Scholar, peer-reviewed journal websites and PubMed database to mainly screen articles on MDA studies with positive and negative results, the World Health Organization guidelines, and other MDA-related reports. We also summarized our historical field experiences on MDA in malaria control to provide informed perspective on the challenges of MDA. Following the spirit of innovation, a comprehensive strategy with MDA at its core and each additional measure compensating one another's shortage based on different malaria transmission settings and stratification could be the highlight of future malaria control and elimination strategy to help achieve the vision of a malaria-free world.

Long non-coding RNAs as possible therapeutic targets in protozoa, and in Schistosoma and other helminths

Long non-coding RNAs (lncRNAs) emerged in the past 20 years due to massive amounts of scientific data regarding transcriptomic analyses. They have been implicated in a plethora of cellular processes in higher eukaryotes. However, little is known about lncRNA possible involvement in parasitic diseases, with most studies only detecting their presence in parasites of human medical importance. Here, we review the progress on lncRNA studies and their functions in protozoans and helminths. In addition, we show an example of knockdown of one lncRNA in Schistosoma mansoni, SmLINC156349, which led to in vitro parasite adhesion, motility, and pairing impairment, with a 20% decrease in parasite viability and 33% reduction in female oviposition. Other observed phenotypes were a decrease in the proliferation rate of both male and female worms and their gonads, and reduced female lipid and vitelline droplets that are markers for well-developed vitellaria. Impairment of female worms' vitellaria in SmLINC156349-silenced worms led to egg development deficiency. All those results demonstrate the great potential of the tools and methods to characterize lncRNAs as potential new therapeutic targets. Further, we discuss the challenges and limitations of current methods for studying lncRNAs in parasites and possible solutions to overcome them, and we highlight the future directions of this exciting field.

Genetic surveillance for monitoring the impact of drug use on Plasmodium falciparum populations

The use of antimalarial drugs is an effective strategy in the fight against malaria. However, selection of drug resistant parasites is a constant threat to the continued use of this approach. Antimalarial drugs are used not only to treat infections but also as part of population-level strategies to reduce malaria transmission toward elimination. While there is strong evidence that the ongoing use of antimalarial drugs increases the risk of the emergence and spread of drug-resistant parasites, it is less clear how population-level use of drug-based interventions like seasonal malaria chemoprevention (SMC) or mass drug administration (MDA) may contribute to drug resistance or loss of drug efficacy. Critical to sustained use of drug-based strategies for reducing the burden of malaria is the surveillance of population-level signals related to transmission reduction and resistance selection. Here we focus on Plasmodium falciparum and discuss the genetic signatures of a parasite population that are correlated with changes in transmission and related to drug pressure and resistance as a result of drug use. We review the evidence for MDA and SMC contributing to malaria burden reduction and drug resistance selection and examine the use and impact of these interventions in Senegal. Throughout we consider best strategies for ongoing surveillance of both population and resistance signals in the context of different parasite population parameters. Finally, we propose a roadmap for ongoing surveillance during population-level drug-based interventions to reduce the global malaria burden.

The acceptability of targeted mass treatment with primaquine for local elimination of vivax malaria in a northern Myanmar township: a mixed-methods study

Background

Radical cure of the Plasmodium vivax latent liver stage is required to effectively manage vivax malaria. Targeted mass treatment with primaquine may be an effective mechanism for reducing reservoirs of the disease. Since community engagement and high coverage are essential for mass treatment programs, this study aimed to determine the acceptability of mass primaquine treatment in a targeted community in a northern Myanmar township.

Methods

A cross-sectional mixed-methods study was deployed among household leaders in July 2019. Face-to-face interviews using structured questionnaires and standardized qualitative guidelines were conducted to gather information. Descriptive and inferential statistics, including logistic regression models, were applied.

Results

Among 609 study respondents, > 90% agreed to participate in an upcoming targeted mass primaquine treatment (TPT) program. Factors contributing to higher odds of acceptability of the program were older age [adjusted odds ratios (aOR): 2.38, 95% confidence intervals (CI) 1.08–8.96], secondary education level (aOR: 3.99, 95% CI 1.12–20.01), having good knowledge of malaria (aOR: 2.12, 95% CI 1.04–4.76), experiencing malaria within the family (aOR: 1.92, 95% CI 1.14–5.13), and believing eliminating malaria from the village is possible (aOR: 2.83, 95% CI 1.07–4.07). Furthermore, 50 community respondents, 6 midwives, and 4 public health staff (grade II) participated in the qualitative component of the study. Many thought that TPT seemed feasible and stressed that high coverage of underserved groups and health education are needed before commencing the activity.

Conclusions

Most respondents agreed to participate in the proposed mass treatment campaign. Older people with secondary education level and those who had experienced malaria within their families were most likely to report willingness to participate. These same individuals may be important in the community engagement process to increase community acceptance of the program.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-05064-y.

Mass drug administration for malaria

BACKGROUND

Studies evaluating mass drug administration (MDA) in malarious areas have shown reductions in malaria immediately following the intervention. However, these effects vary by endemicity and are not sustained. Since the 2013 version of this Cochrane Review on this topic, additional studies have been published.

OBJECTIVES

Primary objectives To assess the sustained effect of MDA with antimalarial drugs on: - the reduction in malaria transmission in moderate- to high-transmission settings; - the interruption of transmission in very low- to low-transmission settings. Secondary objective To summarize the risk of drug-associated adverse effects following MDA.

SEARCH METHODS

We searched several trial registries, citation databases, conference proceedings, and reference lists for relevant articles up to 11 February 2021. We also communicated with researchers to identify additional published and unpublished studies.

SELECTION CRITERIA

Randomized controlled trials (RCTs) and non-randomized studies comparing MDA to no MDA with balanced co-interventions across study arms and at least two geographically distinct sites per study arm.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for eligibility and extracted data. We calculated relative risk (RR) and rate ratios with corresponding 95% confidence intervals (CIs) to compare prevalence and incidence, respectively, in MDA compared to no-MDA groups. We stratified analyses by malaria transmission and by malaria species. For cluster-randomized controlled trials (cRCTs), we adjusted standard errors using the intracluster correlation coefficient. We assessed the certainty of the evidence using the GRADE approach. For non-randomized controlled before-and-after (CBA) studies, we summarized the data using difference-in-differences (DiD) analyses.

MAIN RESULTS

Thirteen studies met our criteria for inclusion. Ten were cRCTs and three were CBAs. Cluster-randomized controlled trials Moderate- to high-endemicity areas (prevalence ≥ 10%) We included data from two studies conducted in The Gambia and Zambia.  At one to three months after MDA, the Plasmodium falciparum (hereafter, P falciparum) parasitaemia prevalence estimates may be higher compared to control but the CIs included no effect (RR 1.76, 95% CI 0.58 to 5.36; Zambia study; low-certainty evidence); parasitaemia incidence was probably lower (RR 0.61, 95% CI 0.40 to 0.92; The Gambia study; moderate-certainty evidence); and confirmed malaria illness incidence may be substantially lower,  but the CIs included no effect (rate ratio 0.41, 95% CI 0.04 to 4.42; Zambia study; low-certainty evidence).  At four to six months after MDA, MDA showed little or no effect on P falciparum parasitaemia prevalence (RR 1.18, 95% CI 0.89 to 1.56; The Gambia study; moderate-certainty evidence) and, no persisting effect was demonstrated with parasitaemia incidence (rate ratio 0.91, 95% CI 0.55 to 1.50; The Gambia study). Very low- to low-endemicity areas (prevalence < 10%) Seven studies from Cambodia, Laos, Myanmar (two studies), Vietnam, Zambia, and Zanzibar evaluated the effects of multiple rounds of MDA on P falciparum. Immediately following MDA (less than one month after MDA), parasitaemia prevalence was reduced (RR 0.12, 95% CI 0.03 to 0.52; one study; low-certainty evidence). At one to three months after MDA, there was a reduction in both parasitaemia incidence (rate ratio 0.37, 95% CI 0.21 to 0.55; 1 study; moderate-certainty evidence) and prevalence (RR 0.25, 95% CI 0.15 to 0.41; 7 studies; low-certainty evidence). For confirmed malaria incidence, absolute rates were low, and it is uncertain whether MDA had an effect on this outcome (rate ratio 0.58, 95% CI 0.12 to 2.73; 2 studies; very low-certainty evidence).  For P falciparum prevalence, the relative differences declined over time, from RR 0.63 (95% CI 0.36 to 1.12; 4 studies) at four to six months after MDA, to RR 0.86 (95% CI 0.55 to 1.36; 5 studies) at 7 to 12 months after MDA. Longer-term prevalence estimates showed overall low absolute risks, and relative effect estimates of the effect of MDA on prevalence varied from RR 0.82 (95% CI 0.20 to 3.34) at 13 to 18 months after MDA, to RR 1.25 (95% CI 0.25 to 6.31) at 31 to 36 months after MDA in one study. Five studies from Cambodia, Laos, Myanmar (2 studies), and Vietnam evaluated the effect of MDA on Plasmodium vivax (hereafter, P vivax). One month following MDA, P vivax prevalence was lower (RR 0.18, 95% CI 0.08 to 0.40; 1 study; low-certainty evidence). At one to three months after MDA, there was a reduction in P vivax prevalence (RR 0.15, 95% CI 0.10 to 0.24; 5 studies; low-certainty evidence). The immediate reduction on P vivax prevalence was not sustained over time, from RR 0.78 (95% CI 0.63 to 0.95; 4 studies) at four to six months after MDA, to RR 1.12 (95% CI 0.94 to 1.32; 5 studies) at 7 to 12 months after MDA. One of the studies in Myanmar provided estimates of longer-term effects, where overall absolute risks were low, ranging from RR 0.81 (95% CI 0.44 to 1.48) at 13 to 18 months after MDA, to RR 1.20 (95% CI 0.44 to 3.29) at 31 to 36 months after MDA. Non-randomized studies Three CBA studies were conducted in moderate- to high-transmission areas in Burkina Faso, Kenya, and Nigeria. There was a reduction in P falciparum parasitaemia prevalence in MDA groups compared to control groups during MDA (DiD range: -15.8 to -61.4 percentage points), but the effect varied at one to three months after MDA (DiD range: 14.9 to -41.1 percentage points).  AUTHORS' CONCLUSIONS: In moderate- to high-transmission settings, no studies reported important effects on P falciparum parasitaemia prevalence within six months after MDA. In very low- to low-transmission settings, parasitaemia prevalence and incidence were reduced initially for up to three months for both P falciparum and P vivax; longer-term data did not demonstrate an effect after four months, but absolute risks in both intervention and control groups were low. No studies provided evidence of interruption of malaria transmission.

What Could Explain the Lower COVID-19 Burden in Africa despite Considerable Circulation of the SARS-CoV-2 Virus?

The differential spread and impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), causing Coronavirus Disease 2019 (COVID-19), across regions is a major focus for researchers and policy makers. Africa has attracted tremendous attention, due to predictions of catastrophic impacts that have not yet materialized. Early in the pandemic, the seemingly low African case count was largely attributed to low testing and case reporting. However, there is reason to consider that many African countries attenuated the spread and impacts early on. Factors explaining low spread include early government community-wide actions, population distribution, social contacts, and ecology of human habitation. While recent data from seroprevalence studies posit more extensive circulation of the virus, continuing low COVID-19 burden may be explained by the demographic pyramid, prevalence of pre-existing conditions, trained immunity, genetics, and broader sociocultural dynamics. Though all these prongs contribute to the observed profile of COVID-19 in Africa, some provide stronger evidence than others. This review is important to expand what is known about the differential impacts of pandemics, enhancing scientific understanding and gearing appropriate public health responses. Furthermore, it highlights potential lessons to draw from Africa for global health on assumptions regarding deadly viral pandemics, given its long experience with infectious diseases.

Spatial and epidemiological drivers of Plasmodium falciparum malaria among adults in the Democratic Republic of the Congo

Background

Adults are frequently infected with malaria and may serve as a reservoir for further transmission, yet we know relatively little about risk factors for adult infections. In this study, we assessed malaria risk factors among adults using samples from the nationally representative, cross-sectional 2013–2014 Demographic and Health Survey (DHS) conducted in the Democratic Republic of the Congo (DRC). We further explored differences in risk factors by urbanicity.

Methods

Plasmodium falciparum infection was determined by PCR. Covariates were drawn from the DHS to model individual, community and environmental-level risk factors for infection. Additionally, we used deep sequencing data to estimate the community-level proportions of drug-resistant infections and included these estimates as potential risk factors. All identified factors were assessed for differences in associations by urbanicity.

Results

A total of 16 126 adults were included. Overall prevalence of malaria was 30.3% (SE=1.1) by PCR; province-level prevalence ranged from 6.7% to 58.3%. Only 17% of individuals lived in households with at least one bed-net for every two people, as recommended by the WHO. Protective factors included increasing within-household bed-net coverage (Prevalence Ratio=0.85, 95% CI=0.76–0.95) and modern housing (PR=0.58, 95% CI=0.49–0.69). Community-level protective factors included increased median wealth (PR=0.87, 95% CI=0.83–0.92). Education, wealth, and modern housing showed protective associations in cities but not in rural areas.

Conclusions

The DRC continues to suffer from a high burden of malaria; interventions that target high-risk groups and sustained investment in malaria control are sorely needed. Areas of high prevalence should be prioritised for interventions to target the largest reservoirs for further transmission.

The Immediate Effects of a Combined Mass Drug Administration and Indoor Residual Spraying Campaign to Accelerate Progress towards Malaria Elimination in Grande-Anse, Haiti

Background

Haiti is planning targeted interventions to accelerate progress toward malaria elimination. In the most affected department (Grande-Anse), a combined mass drug administration (MDA) and indoor residual spraying (IRS) campaign was launched in October 2018. This study assessed the intervention’s effectiveness in reducing Plasmodium falciparum prevalence.

Methods

An ecological quasi-experimental study was designed, using a pretest and posttest with a nonrandomized control group. Surveys were conducted in November 2017 in a panel of easy access groups (25 schools and 16 clinics) and were repeated 2–6 weeks after the campaign, in November 2018. Single-dose sulfadoxine-pyrimethamine and primaquine was used for MDA, and pirimiphos-methyl as insecticide for IRS.

Results

A total of 10 006 participants were recruited. Fifty-two percent of the population in the intervention area reported having received MDA. Prevalence diminished between 2017 and 2018 in both areas, but the reduction was significantly larger in the intervention area (ratio of adjusted risk ratios, 0.32 [95% confidence interval, .104–.998]).

Conclusions

Despite a moderate coverage, the campaign was effective in reducing P. falciparum prevalence immediately after 1 round. Targeted MDA plus IRS is useful in preelimination settings to rapidly decrease the parasite reservoir, an encouraging step to accelerate progress toward malaria elimination.

Perception of Malaria Chemoprevention Interventions in Infants and Children in Eight Sub-Saharan African Countries: An End User Perspective Study

Preventive chemotherapy interventions have been identified as key tools for malaria prevention and control. Although a large number of publications have reported on the efficacy and safety profile of these interventions, little literature exists on end-user experience. The objective of this study was to provide insights on the perceptions and attitudes towards seasonal malaria chemoprevention (SMC) and intermittent preventive treatment of infants (IPTi) to identify drivers of and barriers to acceptance. A total of 179 in-depth qualitative interviews were conducted with community health workers (CHWs), health center managers, parents of children receiving chemoprevention, and national decision makers across eight countries in sub-Saharan Africa. The transcribed verbatim responses were coded and analyzed using a thematic approach. Findings indicate that, although SMC is largely accepted by end users, coverage remained below 100%. The main causes mentioned were children's absenteeism, children being sick, parents' reluctance, and lack of staff. Regarding IPTi, results from participants based in Sierra Leone showed that the intervention was generally accepted and perceived as efficacious. The main challenges were access to water, crushing the tablets, and high staff turnover. SMC and IPTi are perceived as valuable interventions. Our study identified the key elements that need to be considered to facilitate the expansion of these two interventions to different geographies or age groups.

Community acceptability to antimalarial mass drug administrations in Magude district, Southern Mozambique: A mixed methods study

Background

This study aimed to capture the acceptability prior to, during and after the implementation of the first year of MDA rounds conducted under the Magude project, a malaria elimination project in southern Mozambique.

Methods

This was a mixed-methods study, consisting of focus group discussions (FGDs) prior to the implementation of MDA rounds (September 2015), non-participant observations (NPOs) conducted during the MDA rounds (November 2015 –beginning of February 2016), and semi-structured interviews (SSIs) after the second round (end of February 2016). Community leaders, women in reproductive age, general members of the community, traditional healers and health professionals were recruited to capture the opinions of all representing key members of the community. A generic outline of nodes and codes was designed to analyze FGDs and SSI separately. Qualitative and quantitative NPO information was analyzed following a content analysis approach.

Findings

222 participants took part in the FGDs (n = 154), and SSIs (n = 68); and 318 household visits during the MDA underwent NPOs. The community engagement campaign emerged throughout the study stages as a crucial factor for the acceptability of MDAs. Acceptability was also fostered by the community’s general will to cooperate in any government-led activity that would reduce malaria burden, the appropriate behavior and knowledge of field workers, or the fact that the intervention was available free of charge to all. Absenteeism of heads of households was identified as the main barrier for the success of the campaign. The most commonly reported factors that negatively affected acceptability were the fear of adverse events, rumors of deaths, being unable to drink alcohol while taking DHAp, or the fear to take DHAp while in anti-retroviral treatment. Pregnancy testing and malaria testing were generally well accepted by the community.

Conclusion

Magude’s community generally accepted the first and second antimalarial MDA rounds, and the procedures associated to the intervention. Future implementation of antimalarial MDAs in southern Mozambique should focus on locally adapted strategies that engage the community to minimize absenteeism and refusals to the intervention.

Asymptomatic Plasmodium falciparum malaria prevalence among adolescents and adults in Malawi, 2015-2016

Malaria remains a significant cause of morbidity and mortality in Malawi, with an estimated 18–19% prevalence of Plasmodium falciparum in children 2–10 years in 2015–2016. While children report the highest rates of clinical disease, adults are thought to be an important reservoir to sustained transmission due to persistent asymptomatic infection. The 2015–2016 Malawi Demographic and Health Survey was a nationally representative household survey which collected dried blood spots from 15,125 asymptomatic individuals ages 15–54 between October 2015 and February 2016. We performed quantitative polymerase chain reaction on 7,393 samples, detecting an overall P. falciparum prevalence of 31.1% (SE = 1.1). Most infections (55.6%) had parasitemias ≤ 10 parasites/µL. While 66.2% of individuals lived in a household that owned a bed net, only 36.6% reported sleeping under a long-lasting insecticide-treated net (LLIN) the previous night. Protective factors included urbanicity, greater wealth, higher education, and lower environmental temperatures. Living in a household with a bed net (prevalence difference 0.02, 95% CI − 0.02 to 0.05) and sleeping under an LLIN (0.01; − 0.02 to 0.04) were not protective against infection. Our findings demonstrate a higher parasite prevalence in adults than published estimates among children. Understanding the prevalence and distribution of asymptomatic infection is essential for targeted interventions.

Mass radical treatment of a group of foreign workers to mitigate the risk of re-establishment of malaria in Sri Lanka

Background

Following malaria elimination, Sri Lanka was free from indigenous transmission for six consecutive years, until the first introduced case was reported in December 2018. The source of transmission (index case) was a member of a group of 32 migrant workers from India and the location of transmission was their residence reporting a high prevalence of the primary vector for malaria. Despite extensive vector control the situation was highly susceptible to onward transmission if another of the group developed malaria. Therefore, Mass Radical Treatment (MRT) of the group of workers for Plasmodium vivax malaria was undertaken to mitigate this risk.

Method

The workers were screened for malaria by microscopy and RDT, their haemoglobin level assessed, and tested for Glucose 6 phosphate dehydrogenase deficiency (G6PD) using the Care Start RDT and Brewers test prior to treatment with chloroquine (CQ) 25 mg/kg body weight (over three days) and primaquine (PQ) (0.25 mg/kg/day bodyweight for 14 days) following informed consent. All were monitored for adverse events.

Results

None of the foreign workers were parasitaemic at baseline screening and their haemoglobin levels ranged from 9.7–14.7 g/dl. All 31 individuals (excluding the index case treated previously) were treated with the recommended dose of CQ. The G6PD test results were inconclusive in 45% of the RDT results and were discrepant between the two tests in 31% of the remaining test events. Seven workers who tested G6PD deficient in either test were excluded from PQ and the rest, 24 workers, received PQ. No serious adverse events occurred.

Conclusions

Mass treatment may be an option in prevention of reintroduction settings for groups of migrants who are likely to be carrying latent malaria infections, and resident in areas of high receptivity. However, in the case of Plasmodium vivax and Plasmodium ovale, a more reliable and affordable point-of-care test for G6PD activity would be required. Most countries which are eliminating malaria now are in the tropical zone and face considerable and similar risks of malaria re-introduction due to massive labour migration between them and neighbouring countries. Regional elimination of malaria should be the focus of global strategy if malaria elimination from countries is to be worthwhile and sustainable.

Evaluating the Impact of Programmatic Mass Drug Administration for Malaria in Zambia Using Routine Incidence Data

Background

In 2016, the Zambian National Malaria Elimination Centre started programmatic mass drug administration (pMDA) campaigns with dihydroartemisinin-piperaquine as a malaria elimination tool in Southern Province. Two rounds were administered, 2 months apart (coverage 70% and 57%, respectively). We evaluated the impact of 1 year of pMDA on malaria incidence using routine data.

Methods

We conducted an interrupted time series with comparison group analysis on monthly incidence data collected at the health facility catchment area (HFCA) level, with a negative binomial model using generalized estimating equations. Programmatic mass drug administration was conducted in HFCAs with greater than 50 cases/1000 people per year. Ten HFCAs with incidence rates marginally above this threshold (pMDA group) were compared with 20 HFCAs marginally below (comparison group).

Results

The pMDA HFCAs saw a 46% greater decrease in incidence at the time of intervention than the comparison areas (incidence rate ratio = 0.536; confidence interval = 0.337–0.852); however, incidence increased toward the end of the season. No HFCAs saw a transmission interruption.

Conclusions

Programmatic mass drug administration, implemented during 1 year with imperfect coverage in low transmission areas with suboptimal vector control coverage, significantly reduced incidence. However, elimination will require additional tools. Routine data are important resources for programmatic impact evaluations and should be considered for future analyses.

Malaria Elimination in Costa Rica: Changes in Treatment and Mass Drug Administration

Costa Rica is a candidate to eliminate malaria by 2020. The remaining malaria transmission hotspots are located within the Huétar Norte Region (HNR), where 90% of the country's 147 malaria cases have occurred since 2016, following a 33-month period without transmission. Here, we examine changes in transmission with the implementation of a supervised seven-day chloroquine and primaquine treatment (7DCPT). We also evaluate the impact of a focal mass drug administration (MDA) in January 2019 at Boca Arenal, the town in HNR reporting the greatest local transmission. We found that the change to a seven-day treatment protocol, from the prior five-day program, was associated with a 98% reduction in malaria transmission. The MDA helped to reduce transmission, keeping the basic reproduction number, R_T, significantly below 1, for at least four months. However, following new imported cases from Nicaragua, autochthonous transmission resumed. Our results highlight the importance of appropriate treatment delivery to reduce malaria transmission, and the challenge that highly mobile populations, if their malaria is not treated, pose to regional elimination efforts in Mesoamerica and México.