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  • Innovative approaches needed to overcome health system barriers in malaria vaccination

    Innovative approaches needed to overcome health system barriers in malaria vaccination

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    In a review published in BMC Medicine, researchers examined the current literature to investigate malaria vaccination’s challenges in reaching high-risk children and discussed the policy implications.

    They identified health system-related risks that could hinder malaria vaccine effectiveness and proposed solutions to ensure equitable and universal protection against the disease.

    Study: Malaria vaccination: hurdles to reach high-risk children. Image Credit: Media Lens King/Shutterstock.comStudy: Malaria vaccination: hurdles to reach high-risk children. Image Credit: Media Lens King/Shutterstock.com

    Background

    Despite decades of efforts, malaria remains a significant health challenge in Africa, prompting the introduction of RTS,S/AS01, and R21/Matrix-M vaccines.

    These vaccines offer promising advancements but require further investment in research, development, and delivery strategies to maximize their impact.

    Researchers in the present article examined the health system-related risks that could hinder universal malaria immunization, focusing on limited government health financing, vaccine allocation frameworks, and core issues in maximizing impact. The analysis builds upon existing research while delving into policy implications.

    Limited government health financing

    Limited public health financing in most African countries hampers their ability to purchase malaria vaccines in quantities sufficient to cover at-risk children. The number needed to vaccinate (NNV) can be calculated based on vaccine effectiveness (VE) and malaria incidence among unvaccinated children.

    Vaccine wastage (VW) rates must also be considered, which increase with geographical and developmental distance from urban centers.

    The financial investment required to purchase vaccines can overwhelm most countries’ health systems, necessitating reliance on development partners.

    As per the eligibility criteria determined by the Global Alliance for Vaccines and Immunization (Gavi), only 12 African countries have been approved for priority vaccine allocation, covering a small fraction of the at-risk population.

    The introduction of the more cost-effective R21 vaccine may improve supply, but transformative changes in health financing are needed to ensure widespread accessibility.

    Delivery costs pose another barrier, with additional costs per dose needed for administration. Achieving universal coverage would require substantial financial investment, highlighting the challenge of sustaining vaccination efforts without adequate funding.

    Effective planning, funding, and coordination, supported by sustainable health financing models, are essential to maximize the public health impact of malaria vaccines.

    Strengthening vaccine allocation frameworks

    The World Health Organization devised a framework for selecting high-risk areas eligible for Gavi support based on malaria burden and child mortality rates at the district level.

    However, this approach has limitations, relying on outdated data and neglecting emerging issues like antimicrobial resistance (AMDR).

    AMDR, particularly concerning antimalarial drugs, affects malaria control strategies and requires consideration in vaccine prioritization. Current methods overlook dynamic epidemiological trends, hindering accurate needs assessment.

    Updating the prioritization index with recent and comprehensive data is crucial to address these shortcomings. Incorporating AMDR indicators alongside traditional metrics can enhance the accuracy of vaccine allocation.

    Additionally, establishing subnational scoring systems within eligible countries can prioritize districts based on vulnerability and equity considerations.

    These frameworks ensure that vaccines reach the most at-risk children within countries, combating corruption and inequities that often hinder resource distribution.

    Implementing these strategies requires robust data systems and stakeholder engagement to monitor and evaluate vaccine distribution effectively.

    By prioritizing high-risk areas and addressing systemic barriers, malaria vaccines can maximize their impact on child health protection and contribute to achieving sustainable development goals (SDGs).

    Without such measures, vaccines risk perpetuating inequalities, failing to reach the most vulnerable populations. Thus, proactive planning and targeted interventions at both national and subnational levels are essential.

    Tackling core issues

    Immunization efforts against malaria in Africa face challenges similar to those that have hindered routine immunization programs on the continent. Despite continued efforts, progress in routine immunization remains below international standards, with many countries off-track from global targets.

    Sub-Saharan Africa (SSA) shows the highest burden of unvaccinated and under-vaccinated children globally, highlighting systemic weaknesses in vaccination programs.

    Limited vaccine supply, worsened by issues like vaccine wastage, infrastructure deficiencies, corruption, and mismanagement exacerbates these challenges.

    Geographical barriers, including the time taken to travel to healthcare facilities, impede access to routine immunization services, particularly in remote areas.

    Additionally, a lack of investment in sustainable data systems limits evidence-based decision-making and hampers progress in disease control. Without effective data utilization, the root causes of public health inefficiencies remain unaddressed, hindering efforts to combat diseases like malaria.

    Compliance with healthcare financing commitments like the Abuja Declaration and institutional strengthening are essential steps toward overcoming systemic challenges.

    Merely integrating malaria vaccines into existing Expanded Program on Immunization (EPI) frameworks without fundamental changes in health systems may not yield the desired results. Transformative change integrated within immunization efforts is required to maximize their impact on African child health.

    Conclusion

    To effectively combat malaria, lessons from past immunization efforts must inform the deployment of malaria vaccines. A comprehensive assessment program is crucial prior to rollout to identify and address specific challenges.

    By urgently addressing these risks and implementing tailored strategies, the potential of malaria vaccines to contribute to disease control and elimination can be realized.

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  • Ancient malaria genome from Roman skeleton hints at disease’s history

    Ancient malaria genome from Roman skeleton hints at disease’s history

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    A coloured transmission electron micrograph showing a blue and green cell with several organelles inside a red cell.

    The malaria parasite Plasmodium falciparum infecting a red blood cell.Credit: Dennis Kunkel Microscopy/Science Photo Library

    Researchers have sequenced the mitochondrial genome of the deadliest form of malaria from an ancient Roman skeleton. They say the results could help to untangle the history of the disease in Europe.

    It’s difficult to find signs of malaria in ancient human remains, and DNA from the malaria-causing parasite Plasmodium rarely shows up in them. As a result, there had never been a complete genomic sequence of the deadliest species, Plasmodium falciparum, from before the twentieth century — until now. “P. falciparum was eliminated in Europe a half century ago, and genetic data from European parasites — ancient or recent — has been an elusive piece in the puzzle of understanding how humans have moved parasites around the globe,” says Daniel Neafsey, who studies the genomics of malaria parasites and mosquito vectors at the Harvard T.H. Chan School of Public Health in Boston, Massachusetts.

    Malaria has long been a leading cause of human deaths. “With the development of treatments such as quinine in the last hundreds of years, it seems clear [humans and malaria] are co-evolving,” says Carles Lalueza Fox, a palaeogenomicist at the Institute of Evolutionary Biology in Barcelona, Spain. “Discovering the genomes of the ancient, pre-quinine plasmodia will likely reveal information about how they have adapted to the different anti-malarial drugs.”

    Ancient pathogen

    There are five malaria-causing species of Plasmodium, which are thought to have arisen in Africa between 50,000 and 60,000 years ago, and then spread worldwide. Most researchers agree that they reached Europe at least 2,000 years ago, by the time of the Roman Empire.

    Plasmodium falciparum “has significantly impacted human history and evolution”, says Neafsey. “So, that makes it particularly important to discover how long different societies have had to deal with [it], and how human migration and trade activities spread it.”

    Researchers can glean valuable information about the origin, evolution and virulence of the parasite from DNA extracted from the ancient remains of infected people. But it is difficult to know where to look: it is not always obvious whether a person was infected with Plasmodium, and whether DNA can be recovered depends on how well it has been preserved.

    In a preprint posted on the server bioRxiv1, a team of researchers led by a group at the University of Vienna identified the first complete mitochondrial genome sequence of P. falciparum from the bones of a Roman who lived in Italy in the second century ad, known as Velia-186.

    Plasmodium falciparum had been detected in Velia-186 in a previous study2. The authors of the latest preprint extracted the parasite’s DNA from the body’s teeth, and were able to identify 5,458 pieces of unique genetic information that they combined to get a sequence covering 99.1% of the mitochondrial genome. They also used software to compare the genome with modern samples, and found that the Velia-186 sequence is closely related to a group of present-day strains found in India.

    Carried by migration

    The researchers say their findings support a hypothesis that P. falciparum spread to Europe from Asia around at least 2,000 years ago3. The Indian strains “were already present in Europe [then]; thus, a potential arrival with globalization episodes such as the Hellenistic period — when it is first described by Greeks — seems plausible”, says Lalueza Fox.

    Neafsey says the work is a “technical tour de force” and an interesting addition to the limited field of ancient malaria genomics. But he adds that the results should be interpreted with caution because there are only a few samples, and points out that a genome sequence from DNA in the parasite’s cell nuclei, rather than its mitochondria, “might indicate a more complex story of parasite movement among ancient human populations”.

    Lalueza Fox suggests exploring other potential sources of Plasmodium DNA, such as old bones, antique medical equipment and even mosquito specimens in museums. “The integration of genetic data from these heterogeneous sources will provide a nuanced view of this disease,” he says. “It would be interesting to see what lessons we can learn from the past on the strains and dispersals of this pathogen.”

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  • UVM study links deforestation with higher risk of childhood malaria

    UVM study links deforestation with higher risk of childhood malaria

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    Malaria kills more than 600,000 people each year worldwide, and two thirds are children under age five in sub-Saharan Africa. Scientists have found a treatment that could prevent thousands of these deaths: trees. New research conducted at the University of Vermont (UVM) and published today in the journal GeoHealth suggests forests can provide natural protection against disease transmission, particularly for the most vulnerable children.

    Malaria spreads through the bite of Anopheles mosquitoes. While malaria is a disease long associated with lower socioeconomic status, the UVM study links deforestation with higher risk of the disease, particularly for children from poorer households.

    One of the takeaways from this study is in order to have good public health policy it is also important to consider environmental conservation-;not degrade the land and make it suitable for breeding mosquitoes.”


    Tafesse Estifanos, lead author, former postdoc at UVM’s Gund Institute for Environment

    He partnered with UVM faculty members to analyze the prevalence of malaria in six sub-Saharan African countries where the disease is endemic, including Côte d’Ivoire, the Democratic Republic of the Congo, Guinea, Mozambique, Rwanda, and Togo. The team linked demographic and health survey data of over 11,500 children with mosquito range maps and land-use changes to determine how wealth, temperature, precipitation, and forest cover influenced infection rates. They used multi-level mixed effects models to test potential relationships and found the individuals impacted most are those who can least afford it.

    “We have this huge socioeconomic disparity among households,” explains Estifanos.

    The data show that the effect of deforestation on malaria prevalence is strongest in less wealthy communities and where certain mosquito species dominate. Malaria was the most prevalent in the poorest households (40.4%) and least prevalent among the richest (6.2%). Residents of poorer households-;defined using a composite measure of a household’s living standards such as home ownership, dwelling characteristics, type of drinking water sources, toilet facilities, education, occupation, and income characteristics derived from U.S. Agency for International Development (USAID) Demographic and Health surveys-;are also the most likely to live on the fringes of disturbed landscapes that produce favorable breeding conditions for mosquitoes.

    The paper continues a decade of UVM research examining relationships between human health and environmental conditions using a massive global database Gund researchers built using USAID’s data from dozens of developing nations. Tafesse, originally from Ethiopia, studied how malaria infections are influenced by land use changes and went one step further by exploring how various mosquito species affects disease transmission.

    “By asking where and for whom, Tafesse was able to show that deforestation doesn’t affect everyone’s health the same,” says Gund Director Taylor Ricketts. “Those in poorer communities, and those with certain dominant mosquito vectors, are more vulnerable. That helps us target interventions to have the most benefit for the most vulnerable kids.”

    Interventions such as conserving forests. Previous Gund investigations have shown that poorer and more rural communities are often the most affected by ecosystem degradation-;and suffer health consequences such as stunting, malnutrition, and diarrheal diseases.

    “Conserving forests and other nature is not only good for kids’ health, it does the most good for the most vulnerable kids,” Ricketts says.

    Fertile ground for mosquitoes

    Humans alter the landscape wherever we live. We raise livestock and crops. We log and level forests and fields for roads, farms, businesses, and homes. These changes not only alter ecosystems but impact the people who live close to animal species and the diseases they transmit-;like mosquitoes. This is playing out in sub-Saharan Africa where 94 percent of malaria cases worldwide occur alongside significant land use changes.

    Mosquitoes reproduce in standing water found in puddles, buckets, bottles, car tires-;even the hoofprints of livestock after it rains, Estifanos explains.

    Forests may slow malaria transmission by cooling temperatures and reducing the potential for water to pool, which reduces the amount of time, and the number of places mosquitoes can breed.

    And when it comes to malaria, the type of mosquito matters.

    “We have non vector mosquitoes, and we have bad mosquitoes, which are vectors of human malaria parasite. Those vectors and human blood feeding ones are the ones creating this issue,” Estifanos says. “The most efficient malaria vectors are found in sub–Saharan Africa and three are the dominant ones: Anopheles gambiae, Anopheles arabiensis and Anopheles funestus.”

    Two of these species, Anopheles gambiae and Anopheles funestus, are highly anthropophilic––meaning they prefer to feed on human blood meal. The third type, Anopheles arabiensis, feed on livestock but will use human blood meals in their absence.

    The UVM study used spatial data from the Malaria Atlas Project to determine if vector biology and deforestation influence malaria prevalence across landscapes. When the research team disaggregated the data by mosquito species, they found deforestation increased malaria prevalence in regions where the two anthropophilic species are dominant but not where Anopheles arabiensis thrive.

    The findings also strengthen the relationship between deforestation and malaria that previous studies have found and underscores the complexity of factors affecting disease transmission-;including mosquito species and disturbed environments.

    “So often what happens is if a research project is run by an economist or a social scientist, they go deep into the social side-;and then oh, there is forest; if it’s run by an ecologist, they go deep on the ecology side and then go-;oh, well, wealth,” says study co-author Brendan Fisher, a professor in UVM’s Rubenstein School of Environment and Natural Resources. “Tafesse really drilled down on the complexity, the ecological complexity, and the social complexity, and tried to understand them both.”

    Fisher views the sophistication of the study as its strength. The findings add to a growing body of evidence that well-functioning ecosystems benefit humans, particularly the poorest. The benefits of forests are often expressed in economic terms or as a boon to our mental health in western and academic presses, he says. This study shows the benefits of forests in reducing the risk of a deadly infectious disease.

    “We are talking about the forest-;just doing its own thing-;as potentially stemming thousands of deaths a year,” Fisher says. “Yes, forests do a lot of things for us-;cycle water, storage carbon and even ease our anxiety, but we have been building up an evidence base showing that children’s lives are directly dependent on a well-functioning forest ecosystem.

    “And our analysis here suggests that, once again, conservation, at least as the next step, does seem to benefit those who are least likely to be able to afford alternative health measures-;vaccines, bed nets, filtered water, trips to the hospital, antimalarials. All of those benefit a certain set of people whereas forests don’t really care about your wealth.”

    Creating healthier landscapes

    People living in poverty may be unable to adopt behavioral changes that reduce potential exposure to malaria such as making home improvements or acquiring bed nets. Rural populations face obstacles, too. They often have less access to health facilities that can administer early treatment for malaria.

    Climate change poses additional challenges since rising temperatures promote mosquito reproduction. The UVM study found increased temperatures highly associated with malaria prevalence across the region and climate projections for sub-Saharan Africa could make a bad problem worse.

    “Previously there were only a few highland areas that were suited for mosquito breeding or for malaria,” Estifanos says. “But these days, because of deforestation and because of climate change, the temperature is rising and [creating more favorable breeding] conditions.”

    This means malaria is becoming a common problem in both highland and lowland areas.

    “And climate change is not a local issue––it’s a global issue,” Estifanos says.

    That’s why he believes health policy needs to encompass factors beyond one person’s control to mitigate malaria transmission. He points to interventions such as scaling up the use of bed net in areas where malaria is endemic.

    “It is all about controlling mosquitoes that serve as malaria vectors,” Estifanos explains. “The focus should be on making unfavorable conditions for them to reproduce and survive.”

    Keeping forests intact could help.

    Source:

    Journal reference:

    Estifanos, T. K., et al. (2024) Impacts of Deforestation on Childhood Malaria Depend on Wealth and Vector Biology. GeoHealth. doi.org/10.1029/2022GH000764.

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