It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, March 28, 2026
The Lancet Neurology: Over 250,000 deaths from meningitis globally in 2023; over one third in children under five, suggests most comprehensive global assessment to date
In 2023, globally 259,000 people died from meningitis and 2.5 million people were infected with the disease, suggests a study published in The Lancet Neurology. Although death and infection rates have declined significantly since 1990, progress is insufficient to meet the WHO targets of a 50% reduction in infections and 70% reduction in deaths by 2030.
Meningitis is the leading infectious cause of neurological disabilities globally. Since 2000, widespread global vaccine rollout has greatly reduced the number of infections and deaths in both high-income and low-income countries, however progress lags behind other vaccine-preventable diseases.
This study provides the most comprehensive global assessment of meningitis to date. It suggests globally 259,000 people died from meningitis and 2.5 million people were infected with the disease in 2023, with the greatest risk factors for deaths being low birthweight followed by premature birth and air pollution (both household and atmospheric). The burden of disease remained disproportionately high in low-income countries, particularly in the African meningitis belt, where Nigeria, Chad, and Niger recorded the highest death and infection rates. Streptococcus pneumoniae, Neisseria meningitidis, non-polio enteroviruses, and other viruses were the leading causes of death, while non-polio enteroviruses caused the most cases.
Authors say greater efforts, including expanding vaccination programmes, greater antibiotic stewardship, improving access to care, and strengthening diagnostics and monitoring for meningitis, are essential to achieve further reductions in the disease globally.
Global, regional, and national burden of meningitis, its risk factors, and aetiologies, 1990–2023: a systematic analysis for the Global Burden of Disease Study 2023
Article Publication Date
27-Mar-2026
Study in search of a tropical spring is the first to show some birds flip their breeding season in response to climate
Scientists know comparatively little about the breeding seasons of tropical birds. This point is underscored by a new study that shows insect-eating birds in the tropics can postpone breeding by nearly half a year, more than four times as long as previously observed.
Many years of scientific observation and research show that temperate birds nest in the spring, and their breeding seasons rarely vary by more than a few days from year to year for any given species
In contrast, scientists know little about the breeding seasons of tropical birds. The information that does exist suggests that species may shift their breeding times by up to one month at a given site.
The recently published results of a five-year field study show that this variation has been drastically underestimated in tropical mountains, where — in some cases — whole chunks of the community can breed in opposite seasons in response to shifting climates and resource availability.
In 2014, Felicity Newell joined the Florida Museum of Natural History as a doctoral student, then promptly left the country in search of a tropical spring. It’s a concept she started thinking about while doing biological surveys in Honduras. There, a colleague told her about the work of Alexander Skutch, a renowned ornithologist who spent 20 years studying the breeding habits of birds in Costa Rica. Based on this work, he became “convinced that the birds … have a definite nesting season, and its beginning coincides with the return of spring.”
Costa Rica is a tropical country 9 degrees north of the equator, and as such, it does not have the spring and winter seasons associated with temperate regions. Its climate is balmy year-round, which — Skutch noted — gave people “…the impression that, with tropical birds, singing and nesting continue freely throughout the year.”
Skutch combined the observations he’d made over 20 years with those from other naturalists and determined that this was not the case. Tropical birds, it seemed, primarily nested when their resources were abundant. For birds that eat insects, called insectivores, this occurred from March through June, aligning with the spring breeding season of birds further north. Hence, the concept of a tropical spring.
Back in Honduras, Newell was intrigued. She read up on similar studies to see what had been learned since Skutch’s initial discovery, which he’d published in 1950. But research on the breeding habits of tropical birds was scarce. Much of the work that had been done was anecdotal, lacking data on rainfall and other climate variables and often combining all the observations from a particular country or region. That meant that any local variation in breeding times would be effectively invisible.
“I realized we actually didn’t know how the whole ecosystem worked at all,” Newell said. So she decided to conduct her own study, developing a new project from scratch on tropical montane birds with colleague Ian Ausprey; both Newell and Ausprey are now asisstant professors at Texas A&M University, and were advised by study co-author Scott Robinson, the Ordway eminent scholar at the Florida Museum.
They found a spot in the cloud forests of northern Peru where they lived with local families and communities and collected data for the next five years.
“It was a massive undertaking,” Newell said. “We’d leave before it was light and spend 12 hours in the fields, hiking up mountains in the mud and rain, often getting back after dark. We worked with over 20 field assistants, many from across Peru and Latin America.”
An important decision they had to make early on was how to go about monitoring birds and how to distinguish between those that were breeding and those that weren’t. The obvious and most direct strategy would be to locate nests, which Newell had gotten good at while studying migratory songbirds in the Appalachians. This type of work is long and arduous, but it initially suited Newell just fine.
“I’m kind of obsessed with nests. Actually, that was the original goal of the study, to spend more time looking for nests. But then I realized I didn’t even know when the birds were nesting, and I didn’t have 20 years to find out like Alexander Skutch.” She also had a lot more ground to cover. While Skutch had mostly stuck to one spot, Newell and Ausprey were sampling on eight separate mountains over an area spanning more than 60 miles.
So they settled on mist nets, a reliable and widely used tool among ornithologists everywhere, though they still made note of any nests that they could find.
After netting a bird, they looked for any signs of recent breeding, such as the downy feathers of juvenile birds or a cloacal protuberance on males, which would indicate their readiness to mate. If they had a female, they’d search for a brood patch, which forms when they “lose the feathers on their abdomen, which becomes more vascularized to help incubate the eggs,” Newell said.
Newell wanted to know when tropical birds were nesting, but she also wanted to know what environmental factors were correlated with breeding. So she, Ausprey and the field assistants also measured the abundance of flowers and fruit, recorded rainfall and collected insect biomass data by “vigorously beating the nearest shrub several times over a sweep net.”
At the end of five years, they’d captured and released more than 8,000 birds, documented nearly 4,000 breeding events (such as the presence of juveniles), collected 48,000 insects and found 318 nests.
Finally, they conducted analyses to determine how all of these factors influenced each other. The results caught Newell off guard.
“I wasn’t expecting this amount of variation,” she said. In temperate regions, she explained, the start of the nesting season for a given species can vary annually by three to five days. Research done in the tropics suggested breeding times could vary by a few weeks, potentially even a month. What Newell found was much more than that.
“There was a massive amount of variation, and not just in individual species. Whole chunks of the community were shifting, both spatially and temporally in different ways.”
Tropical environments may not have a true spring, but they do have pronounced wet and dry seasons. Skutch found that most of the birds at his site nested at the tail end of the dry season, just as the rains were beginning to return, stirring plants from their torpor as they busily transformed water into fresh, new leaves, and insects turned those leaves into chitin, hemolymph and viscera. Skutch likened this flush of activity to spring, but the reality is more nuanced and complex.
To tease apart the subtleties, Newell divided the birds into three groups based on their diet: nectarivores, frugivores and insectivores.
The first two groups had fairly predictable patterns that aligned with previous data. Nectar drinkers, like hummingbirds, built nests at the beginning of the dry season, when bird-pollinated flowers were in bloom. Fruit-eating birds, such as tanagers, built their nests during the wet season, when fruit was abundant.
But insectivores couldn’t seem to make up their mind.
“They might breed in June in one year, and if the next year was dry they would breed in May, so they’re varying temporally by about a month,” which isn’t particularly unusual, she said. “However, within 60 miles of each other, one insectivore community might breed in May and the other community might breed in October.”
That was unusual. No other study had shown that tropical birds could put off breeding by nearly half a year.
The point at which a community seesawed between seasons was strongly correlated with insect abundance, to the extent that Newell could pinpoint the average weight of insect biomass at which the scales tipped; 43 milligrams per square meter was the magic number. If the average weight of insects in a square meter remained adequate during the dry season across decades, insect-eating birds would nest as rain tapered off; anything below that number, and the whole community would flip to breed at the beginning of the rainy season, as Skutch had found in Costa Rica.
In the tropics, the abundance of insects is directly tied to rainfall, a fact that Newell knows firsthand. In a separate analysis of the data she’d collected in Peru, she was again caught off guard when the results showed that tropical insects seem to have a Goldilocks preference for the amount of rainfall. Too little is obviously bad, but too much rainfall can similarly reduce their abundance and biomass.
“Intermediate rainfall is where their biomass is highest,” she said. Similar to tropical birds, little is known about the biology of tropical insects. Newell’s results were the first to show that too much rainfall can be detrimental to their abundance, and even now, the functional relationship between the two remains unclear.
This leaves both insects and the animals that eat them especially susceptible to global climate change. Long-term studies have documented declines in many tropical bird species, especially insectivores, and changes in insect biomass could explain some of these declines.
The team’s work has also shown deforestation in the Andes Mountains has jeopardized the existence of hundreds of birds that are specially adapted to the green-tinted gloom created by densely packed tropical trees.
The authors published their study in the journal Global Change Biology.
Credit: Niek Scheepens, Goethe University Frankfurt
FRANKFURT. The large-scale experiment began in autumn 2017 with 360 small plastic tubes containing a mixture of Arabidopsis thaliana seeds, an inconspicuous annual plant with small white flowers. The tubes were shipped to 30 locations across Western and Northern Europe, the Mediterranean region, and the United States. At each site, biologists from a global network sowed the seeds in twelve plots, each about a quarter of a square meter, establishing twelve Arabidopsis populations. These populations persisted into the following year thanks to their seeds.
For up to five years, researchers monitored plant growth and performance and collected tissue samples annually for genetic analysis. Their shared goal: to trace how plants evolve to adapt to highly diverse environments.
Plant samples from the first three years have now been genetically analyzed by the U.S. team. The result: in most climate zones, populations survived and adapted to their local environmental conditions. This became evident through millions of changes across their entire set of genes—the genome. Many of these genomic changes were statistically similar across all twelve populations at a given site. Moreover, sites with similar climates exhibited similar genetic changes, affecting genes related to traits such as drought tolerance or flowering time.
Scheepens explains: “Both findings show how climate exerts evolutionary selection pressure, favoring genes and gene variants that help the plant better adapt to its environment.”
However, some thale cress populations – mostly at particularly hot and dry sites – went extinct after three years, leaving their plots barren. Genome analyses revealed that strong genetic fluctuations had preceded these extinctions, and the twelve populations did not evolve in the same direction. Scheepens notes: “In these populations, random changes apparently dominated due to the relatively small population size within each plot. Instead of successful adaptation, so-called ‘genetic drift’ prevailed.”
Evolutionary ecologist Niek Scheepens concludes: “With this experiment, we can watch evolution unfold almost in real time. It demonstrates that evolutionary adaptation can occur very rapidly – provided sufficient genetic diversity is present. Rare plant species with small populations and low genetic diversity are therefore poorly equipped to cope with environmental changes, including climate change. Overall, our experiment is a compelling appeal to preserve biodiversity: diversity ensures survival.”
. Rapid adaptation and extinction in synchronized outdoor evolution experiments of Arabidopsis.
Article Publication Date
26-Mar-2026
UH OH
Malaria-transmitting mosquitoes in South America evolving to evade insecticides
Sequencing of complete genomes of Anopheles darlingi mosquitoes in Americas finds resistance may make them harder to kill
Harvard T.H. Chan School of Public Health
Key points:
Anopheles darlingi mosquitoes—a major vector of malaria in South America—are evolving in response to insecticides, which may make them harder to kill and malaria more difficult to control on the continent and around the world.
This study is the first to sequence a large number (>1000) of complete genomes of Anopheles mosquitoes in the Americas, where malaria remains stubbornly persistent.
According to the researchers, the findings contribute to a knowledge base that could help improve methods for controlling malaria and provide a template for needed additional research on other Anopheles species in the Americas.
Boston, MA—Anopheles darlingi mosquitoes—a major vector of malaria in South America—are evolving in response to insecticides, which may make them harder to kill and malaria more difficult to control, according to a new study led by Harvard T.H. Chan School of Public Health.
The study will be published March 26, 2026, in Science. It is the first study to sequence a large number (>1000) of complete genomes of Anopheles mosquitoes in the Americas, where there are more than 600,000 cases of malaria annually, mostly in Brazil, Colombia, and Venezuela.
“Malaria remains stubbornly persistent in South America, and there is a risk that dangerous drug-resistant strains of the malaria parasite could evolve in the Americas and then spread elsewhere,” said corresponding author Jacob Tennessen, research scientist in the Department of Immunology and Infectious Diseases. “Our study plays a major role in revealing the evolutionary dynamics of a primary malaria vector, providing new insights into Anopheles darlingi biology that could help improve methods for blocking disease transmission.”
Prior studies on Anopheles darlingi population genetics have used sets of genetic markers but not the whole genome. For this study, the researchers generated whole genome sequences for 1,094 adult female Anopheles darlingi mosquitoes from 16 locations—including forests, wetlands, grasslands, farming and mining areas, and cities—across six South American countries: French Guiana, Brazil, Guyana, Peru, Venezuela, and Colombia.
The study found that Anopheles darlingi are evolving to evade insecticides—a novel result. “Insecticide resistance has only been sporadically documented in Anopheles darlingi, which have not been subject to intensive insecticide-heavy campaigns like those elsewhere in the world,” Tennessen said. “We were not expecting to see resistance-related genes evolving as much as we did, and in so many different countries. Resistance may be driven by agricultural insecticides rather than those used for vector control specifically.”
The researchers also found extensive genetic divergence among Anopheles darlingi mosquitoes across the continent—for example, between those in Guyana versus Venezuela—and observed that the species is well poised to adapt to changes in its environment.
According to the researchers, the study is a milestone for vector biology in the Americas and provides a template for future studies of other Anopheles species in the region. While the study findings contribute to a knowledge base that can inform malaria control efforts, “this was basic research rather than an applied study,” said senior author Daniel Neafsey, associate professor of immunology and infectious diseases. “Additional research is required before any policy changes are implemented.”
Other authors included the Neafsey Lab’s Raphael Brosula, Angela Early, Margaret Laws, and Katrina Kelley, and Harvard Chan’s Nicholas Arisco and Marcia Castro.
Article information
“Population genomics of Anopheles darlingi, the principal South American malaria vector mosquito,” Jacob A. Tennessen, Raphael Brosula, Estelle Chabanol, Sara Bickersmith, Angela M. Early, Margaret Laws, Katrina A. Kelley, Maria Eugenia Grillet, Dionicia Gamboa, Eric R. Lucas, Jean- Bernard Duchemin, Martha L. Quiñones, Maria Anice Mureb Sallum, Eduardo S. Bergo, Jorge E. Moreno, Sanjay Nagi, Nicholas J. Arisco, Mohini Sooklall, Reza Niles- Robin, Marcia C. Castro, Horace Cox, Mathilde Gendrin, Jan E. Conn, Daniel E. Neafsey, Science, March 26, 2026, doi: 10.1126/science.adw9761
This study was supported by the National Institutes of Health (U19AI110818 and R01AI110112), the Bill & Melinda Gates Foundation (INV- 009416), Agence Nationale de la Recherche (ANR- 18- CE15- 0007), and the National Council for Scientific and Technological Development (303382/2022- 8).
Harvard T.H. Chan School of Public Healthis a community of innovative scientists, practitioners, educators, and students dedicated to improving health and advancing equity so all people can thrive. We research the many factors influencing health and collaborate widely to translate those insights into policies, programs, and practices that prevent disease and promote well-being for people around the world. We also educate thousands of public health leaders a year through our degree programs, postdoctoral training, fellowships, and continuing education courses. Founded in 1913 as America’s first professional training program in public health, the School continues to have an extraordinary impact in fields ranging from infectious disease to environmental justice to health systems and beyond.
An international research team led by the University of Vienna has produced, for the first time, high-resolution global maps of invasion risk for thousands of alien plant species under current conditions and future climate and land use scenarios. Their results show that global hotspots of plant invasion risk will shift geographically, with temperate regions facing increasing risks, while risks may decline in some subtropical areas. The study was published in Nature Ecology & Evolution.
The introduction of alien species into new regions by humans has become a defining signature of the Anthropocene, with an increasing number becoming widespread and exerting severe negative impacts on native species and human livelihoods. Many alien plants reduce agricultural yields, while others, such as allergenic ragweed, affect human health. Against this background, the researchers asked how global hotspots of plant invasion risk may change under future environmental conditions.
About the study
The researchers combined global data on alien plant distributions with environmental variables to model the invasion risk of 9,701 species. Using high-resolution data and robust modelling approaches, they assessed current patterns and projected future changes under different climate and land use scenarios until the end of the 21st century.
Hotspots of plant invasion are centered in subtropical regions
"Overall, we found that one third of the global land surface is currently suitable for at least 10 % of these alien species, making these areas invasion hotspots, where many alien plants are expected to occur", biodiversity researcher Ali Omer from the Department of Botany and Biodiversity Research at the University of Vienna and lead author of the study explains. He adds: "Most of these current hotspots are located in subtropical and warm temperate regions, including already large parts of Europe."
Current hotspots of plant invasion will shift poleward
"The results indicate that while the overall extent of hotspots may increase only moderately, their distribution will change substantially", explains biodiversity expert and senior author of the study Franz Essl, University of Vienna. This finding indicates that Europe belongs to the regions facing some of the highest invasion risks worldwide.
Hotspots are expected to shift poleward into colder regions such as Central Europe and contract in increasingly hot and dry subtropical semi-arid regions. In Europe, species such as ragweed with its highly allergenic pollen and black locust, which invades forests and grasslands, are expected to become more widespread under a warming climate. Remote areas in boreal and polar regions are also projected to become more susceptible to plant invasions, causing rising negative impacts on these currently often untouched ecosystems.
New set of alien plants replaces current alien plants
"Not only the location of the invasion hotspots but also the identity of invading species is expected to change", Ali Omer highlights an important finding of the study. Under severe climate change, there may be little overlap between current and future assemblages of non-native plant species in some regions, indicating substantial species turnover. "We expect a new set of alien plant species adapted to warmer conditions to invade many regions", Essl adds.
Rising impacts by alien plants are expected in many densely populated areas
The study highlights the dynamic nature of plant invasions under global change. The shift of invasion hotspots towards densely populated temperate regions is likely to increase impacts on native biota and human well-being. This first high-resolution global assessment of invasion risk for thousands of alien plant species provides an important basis for developing proactive and region-specific management strategies to reduce the impacts of biological invasions under changing environmental conditions.
Summary
Global modelling of 9,701 alien plant species under current and future conditions
Current invasion hotspots are concentrated in subtropical and warm temperate regions
Hotspots are projected to shift towards temperate regions under climate and land use change
Species composition is expected to change substantially in many regions
Increasing risks in densely populated areas highlight the need for region-specific management strategies
Fig. 2: The orange hawkweed is planted as a garden plant, and then sometimes escapes cultivation in large stands.
Credit
F. Essl
About the University of Vienna:
At the University of Vienna, curiosity has been the core principle of academic life for more than 650 years. For over 650 years the University of Vienna has stood for education, research and innovation. Today, it is ranked among the top 100 and thus the top four per cent of all universities worldwide and is globally connected. With degree programmes covering over 180 disciplines, and more than 10,000 employees we are one of the largest academic institutions in Europe. Here, people from a broad spectrum of disciplines come together to carry out research at the highest level and develop solutions for current and future challenges. Its students and graduates develop reflected and sustainable solutions to complex challenges using innovative spirit and curiosity.
