Monday, July 17, 2023

THE SHOW ME STATE

University of Missouri researchers driving innovative solutions to advance use of ‘plastic’ roads


Members of the Mizzou Asphalt Pavement and Innovation Lab are on the leading-edge of developing sustainable plastic waste road pavement mixtures


Business Announcement

UNIVERSITY OF MISSOURI-COLUMBIA

Driving innovative solutions for advancing use of ‘plastic’ roads 

VIDEO: UNIVERSITY OF MISSOURI RESEARCHERS ARE ON THE LEADING-EDGE OF DEVELOPING SUSTAINABLE PLASTIC WASTE ROAD PAVEMENT MIXTURES. view more 

CREDIT: UNIVERSITY OF MISSOURI



Millions of roads across the United States are constructed with asphalt pavement that’s deteriorating over time. Now, researchers at the University of Missouri are using recyclables, including plastic waste, as a sustainable solution to fix America's fracturing road system.

In partnership with the Missouri Department of Transportation (MoDOT), researchers from the Mizzou Asphalt Pavement and Innovation Lab (MAPIL) recently created a real-world test road using recycled materials like scrap tires and plastic waste along a portion of Interstate 155 in the Missouri Bootheel. By increasing the sustainability of asphalt mixes, this innovative method can help reduce the number of items going into landfills or leaking into the environment, said Bill Buttlar, director of MAPIL.  

“Missouri is the Show-Me State, so we take a very pragmatic view,” Buttlar said. “The science can be thorny and difficult, but we are up to the task. We’re excited that while our approach is complicated in the lab, its simple to execute in the field, so it makes it easily adaptable, scalable and cost-effective to incorporate into many types of road environments.”

The I-155 project takes the group’s previous test road, installed along a stretch of Stadium Boulevard in Columbia, Missouri, one step further. Instead of just testing four different types of recycled materials, the I-155 project will evaluate the real-world effectiveness of nine different types of recycled materials in the creation of asphalt pavement. This includes three different types of polyethylene (PE) — a material commonly found in plastic grocery bags — and ground tire rubber, which is a newer way of disposing scrap tires.

“These projects afford us an opportunity to intentionally build the next generation of roads with these materials not as a type of linear landfill, but to also help the environment while making the value of dollars spent on transportation infrastructure like this stretch farther into the future,” said Buttlar, who is also the Glen Barton Chair in Flexible Pavements.

MU is on the leading-edge of this type of work in the U.S. because its team has addressed most of the translational research questions like durability and safety that could prevent a general contractor or department of transportation from adopting this ground-breaking strategy.  

“We don’t just live in the laboratory,” Buttlar said. “In the field of transportation material research, we need to see how all the various materials used to construct a road — the rock, the asphalt and the recycled materials — behave in the real world and gel together to build a road. Asphalt is liquified with heat, and when you put an additive in like a plastic or rubber material, you must get everything to bond together with good adhesion. But we’re only going to know if that happens successfully when we produce it on a full-scale level and then expose it to elements, such as different weather conditions and heavy traffic.”

MAPIL specializes in a dry process, which allows the researchers to easily add the recyclables directly into the mixture before it’s applied to a road surface.  

“The form, shape and size of the plastics bring different challenges in how the material flows, how it behaves and how it mixes,” said Punya Rath, an assistant research professor in the Department of Civil and Environmental Engineering who works at MAPIL. “So, we did extensive small-scale testing for almost an entire year before we moved to a larger scale out in the field with contractors.”

One advantage of this process is that the researchers can test the mixtures in the field using a mobile research lab, which they developed and used for both the Stadium Boulevard and I-155 projects.

“It helps the Missouri Department of Transportation (MoDOT) immensely to have a mobile research lab on-site in the field that has the ability to rapidly test samples and provide results within 24-48 hours to better inform the process,” Rath said.

Citing environmental concerns, Buttlar said the team makes sure everything they do is within the current limits as established by the Environmental Protection Agency (EPA).

“We are designing the material to be able to hold or capture the environmental by-products at the highest percentage for the longest amount of time. It’s not going to be a 100% containment,” Buttlar said. “Everything built in a natural environment will degrade over time, so that’s why EPA has standards for everything, and we make sure we are safely within those standards.”

In partnership with MoDOT, University of Missouri researchers recently created a real-world test road using recycled materials along a portion of Interstate 155 in the Missouri Bootheel.

CREDIT

Graphic by Samantha Novak/University of Missouri

An asphalt pavement test mixture sample designed by the Mizzou Asphalt Pavement and Innovation Lab is ready for further lab testing to determine its strength and durability.


Lab staff in the Mizzou Asphalt Pavement and Innovation Lab show the plastic waste particles that are being added to the pavement mixture. The lab is located inside the University of Missouri College of Engineering.

A pavement mixture using recycled plastic is applied to a section of Stadium Boulevard in Columbia near U.S. Highway 63 in 2021.


Steam rises from the newly poured plastic waste pavement mixture as an asphalt roller compacts the mixture into a smooth driving surface along Stadium Boulevard in Columbia in 2021.

CREDIT

University of Missouri

Editor’s Note:

Both the Stadium Boulevard and I-155 projects were developed in collaboration with the Missouri Department of Transportation (MoDOT) as part of their ongoing partnership with the University of Missouri System’s Missouri Center for Transportation Innovation (MCTI). While both projects only involved repairing an existing road surface, Buttlar said there have been some preliminary talks between his team and MoDOT on how to incorporate more sustainable asphalt pavement mixtures into the building of a third lane on Interstate 70 across Missouri.

For more on the story, please see:

 

What causes mudslides and floods after wildfires? Hint: It’s not what scientists thought


Peer-Reviewed Publication

UNIVERSITY OF SOUTHERN CALIFORNIA



In 2020, one of the largest wildfires in Los Angeles County raged across the San Gabriel Mountains, scorching more than 115,000 acres, damaging or destroying over 150 structures and raining ash and smoke down on pandemic-weary Angelenos.

But even after exhausted firefighters had finally snuffed out the flames, the Bobcat Fire — like other so-called “mega-fires” that have become more common due to climate change — carried the potential to wreak more havoc in its wake. As rainstorms deluge burnt areas, flooding, mudslides and debris flow can compound the fire’s damage.

Understanding how water accumulates and monitoring the movement of runoff and streamflow in burn areas helps authorities predict when and where these post-wildfire events might occur so they can provide affected residents with early warning of flash flooding and debris movement.

A slippery slope

Common knowledge has long held that loss of vegetation during a fire leaves soil vulnerable to erosion because the plant roots that hold the soil in place wither and die. Scientists, however, have long held a different view, that as leaves burn, their waxy coating forms an organic, oily substance on the soil’s surface. This waxy coating creates a water-repellant layer at or near the surface. Scientists believed this layer prevented the ground from absorbing water, resulting in rapid water runoff akin to a Slip ‘N Slide that carries mud and debris.

New research published in Nature Communications has called that scientific theory into question.

A watershed finding

Images of the 2020 Bobcat Fire area indicate soil burn severity and the locations the researchers studied. (Image Source: a- USDA Forest Service; b- A.J. West; d- PlĂ©iades ©CNES, Distribution AIRBUSDS, sourced via SkyWatch Space Applications Inc., and USGS 3D Elevation Program.)

Scientists at the USC Dornsife College of Letters, Arts and Science, in collaboration with researchers from the University of Michigan, the U.S. Geological Survey and Rutgers University, monitored two wet seasons following the Bobcat Fire, from December 2020 to March 2022. The team concluded that water was, in fact, being absorbed by the burnt ground that contained this waxy coating.

Specifically, the team studied three watersheds — areas of land that drain rainfall and snowmelt into streams and rivers — in Southern California’s San Gabriel Mountains. Two of the watersheds burned during the 2020 Bobcat Fire and the other was mainly untouched.

The researchers found that post-wildfire, a significant portion of the water flow in all three watersheds came from water that had been absorbed in the ground.

Joshua West, professor of Earth sciences who led the study at USC Dornsife, said it was no surprise that the flow of water and debris in the burned area’s stream was four to 10 times greater than the flow in the unburnt area’s stream. What he didn’t expect was that stormwater had permeated the ground in both of the burnt watersheds.

This finding contradicted scientists’ previous beliefs that little water would be absorbed in the burnt watershed due to the presence of waxy soils.

In the unburnt watershed, however, the researchers found that trees absorbed the water as anticipated, preventing it from reaching streams.

West and PhD candidate Abra Atwood surmised that, in keeping with the popular notion, increased water in rivers originated from the burnt areas because burned trees and vegetation could not retain water in their roots as they normally would, but not from the inability of the soil to absorb water.

The research team’s finding that the water-repellant layer does not prevent water from being absorbed into the soil strengthened their hypothesis that the water in streams comes from both rainfall and groundwater, leading to increased flooding in burnt areas versus unburnt.

Water build-up poses enduring threat

Identifying areas that are at high-risk for debris flow and mudslides and accurately predicting the amount of debris flow following rainfall in burn areas depends on understanding how water infiltrates the soil in different areas and how it contributes to the flow of streams.

Also, the dynamics of water flow and how water accumulates below the surface can significantly impact how quickly landscapes recover after a wildfire. This recovery affects the stability of hill slopes and helps buffer forests against severe drought.

On the flip side, water accumulation can contribute to landslides for up to four years after a fire as pressure builds up in the soil.

“The underground water accumulation suggests that the potential for landslides extends far beyond the two years following the fire, posing an enduring problem,” West said. “The abundance of water stored in areas affected by the Bobcat Fire, for example, could serve as a harbinger of future flooding concerns in the years to come.”

West is confident that the study’s findings hold important information that can be used by the USGS to improve burn area monitoring and predict flooding and mudslides after a wildfire.

About the study

Funding was provided USC Dornsife’s Department of Earth Sciences and the National Science Foundation.

 

New NIST measurements aim to advance and validate portable MRI technology


A new wave of smaller, less expensive, and portable MRI systems promises to expand the delivery of health care and the capabilities of medicine


Peer-Reviewed Publication

NATIONAL INSTITUTE OF STANDARDS AND TECHNOLOGY (NIST)

Low Field MRI 

IMAGE: KALINA JORDANOVA, STEPHEN OGIER AND KATY KEENAN ARE AMONG THE NIST RESEARCHERS WHO HAVE BEEN WORKING ON SEVERAL PROJECTS THAT AIM TO ADVANCE MRI TECHNOLOGY THAT USES LOWER-STRENGTH MAGNETIC FIELDS AND VALIDATE ITS APPROACHES FOR CAPTURING IMAGES WITH WEAKER MAGNETIC FIELDS. view more 

CREDIT: R. JACOBSON/NIST



Magnetic resonance imaging (MRI) machines can clearly view non-bony parts of the body — soft tissue such as the brain, muscles and ligaments — as well as detect tumors, making it possible to diagnose many diseases and other conditions. However, the powerful magnets in conventional MRI machines make them expensive and bulky, confining them mainly to hospitals and other large facilities. 

As an alternative solution, companies are developing new portable versions that have lower-strength magnetic fields. These new models can potentially expand the ways in which MRI is used. For instance, low-field MRI systems could be deployed in ambulances and other mobile settings. They also could cost much less, promising to make MRI more widely available, including in underserved communities and developing nations. 

But for low-field MRI scanners to reach their full potential, more research is needed to understand the relationship between low-field images and the underlying tissue properties they represent. Researchers at the National Institute of Standards and Technology (NIST) have been working on several fronts to advance low-field MRI technology and validate methods for creating images with weaker magnetic fields.

“Magnetic resonance images of tissue differ depending on magnetic strength,” said NIST electrical engineer Kalina Jordanova. “With low-field MRI systems, the contrast of the images is different, so we need to know how human tissue looks at these lower field strengths.” 

Toward these ends, researchers measured the properties of brain tissue at low magnetic field strength. Their results were published in the journal Magnetic Resonance Materials in Physics, Biology and Medicine.

The researchers used a commercially available portable MRI machine to image brain tissue in five male and five female volunteers. The images were created using a magnetic field strength of 64 millitesla, which is at least 20 times lower than the magnetic field in conventional MRI scanners.  

They collected images of the entire brain and obtained data on its gray matter (which has a high concentration of nerve cells), white matter (deeper tissues of the brain that house nerve fibers), and cerebrospinal fluid (clear fluid surrounding the brain and spinal cord). 

These three brain constituents respond to the low magnetic field in different ways and produce distinctive signals that reflect their unique properties, enabling the MRI system to produce images that contain quantitative information about each constituent. “Knowing the quantitative properties of tissue allows us to develop new image collection strategies for this MRI system,” said NIST biomedical engineer Katy Keenan. 

In separate work, NIST researchers are exploring several candidate materials that can significantly boost image quality in low-field MRI scans.

MRI contrast agents — magnetic materials that are injected into patients and enhance image contrast — make it easier for radiologists to identify anatomical features or evidence of disease and are routinely used in MRI at conventional magnetic field strengths. However, researchers are just starting to understand how contrast agents might be used with the new low-field MRI scanners. At the lower field strengths of these scanners, contrast agents may act differently than at higher field strengths, creating opportunities to use new types of magnetic materials for image enhancement. 

NIST scientists and their colleagues compared the sensitivity of several magnetic contrast agents in low magnetic fields. The researchers found that iron oxide nanoparticles outperformed traditional contrast agents, which are made of the element gadolinium — a rare-earth metal. At low magnetic field strength, the nanoparticles provided good contrast using a concentration of only about one-ninth that of the gadolinium particles.

Iron oxide nanoparticles also offer the advantage that they are broken down by the human body instead of potentially accumulating in tissue, noted NIST researcher Samuel Oberdick. By comparison, a small amount of gadolinium may accumulate in tissue and could confound the interpretation of future MRI scans if it is not taken into account.

NIST researchers collaborated with the University of Florence in Italy and Hyperfine Inc. in Guilford, Connecticut, and reported their findings in the journal Scientific Reports.

NIST researcher Sam Oberdick explored contrasts agents for MRI machines along with his cohort. His group tested iron oxide nanoparticles at lower-strength magnetic fields. These nanoparticles inside the liquid solution (pictured here) are magnetic and are pulled toward the magnet through a combination of magnetic interactions and surface tension.

CREDIT

R. Wilson/NIST

Rice study: Men vastly outnumber women in studying legislative politics


Peer-Reviewed Publication

RICE UNIVERSITY




It’s no secret that men outnumber women in the halls of Congress and in other political arenas, but new research from Rice University, the University of Wisconsin-Madison and the University of Illinois Urbana-Champaign also found that significantly more men than women study the legislative process in the U.S. and abroad.

This has troubling implications for the inner workings of the discipline and the overall study of topics that impact women’s political involvement, according to Leslie Schwindt-Bayer, the Thomas Cooke and Mary Elizabeth Edwards Chair in Government and Democracy and one of the authors of “Women in Legislative Studies: Improving Gender Equality.” The article appears in an upcoming issue of Political Science & Politics.

For their study, Schwindt-Bayer and fellow authors Eleanor Neff Powell at the University of Wisconsin–Madison and Gisela Sin from the University of Illinois Urbana-Champaign surveyed 361 women studying political science with a focus in legislative politics to understand why gender representation in the field is so imbalanced and what can be done about it.

Schwindt-Bayer said that while many women study legislatures, they do not always identify as scholars of legislative studies.

“We argue that one big reason for this low representation may be that women are less likely to call themselves legislative scholars and do not perceive the field as inclusive,” she said. “When asked what problems they perceive with the section of scholars studying legislative politics, the most common critique was that the field was male-dominated. Nearly 40 percent raised this concern; another 21 percent commented on the lack of ethnic and racial diversity.”

Other problems cited included an overemphasis on the U.S. Congress (21 percent) and the subfield being too cliquey/exclusive (28 percent).

Being underrepresented means that networking opportunities and scholarly resources for women are more scarce, in addition to there being fewer female mentors and letter writers for promotion and tenure. The representation imbalance also reinforces gender bias when it comes to authoring research, graduate training, and publication and citation rates for women in the field.

“It’s especially troublesome when you consider that female authors are significantly more likely than male authors to cite studies by women,” Schwindt-Bayer said. “This lack of representation puts women at a real disadvantage in this field.”

The researchers also looked at articles in Legislative Studies Quarterly (LSQ), a prominent political science journal focused on this political science subfield, between 2016 and August 2018. In the issues published during this time period, 59 percent of the 73 articles were authored by men, 18 percent by women and 23 percent by mixed-gender teams. These percentages are representative of women in the subfield but are small nonetheless.

“It was plain as day — women are just not well-represented in this branch of the American Political Science Association (APSA),” Schwindt-Bayer said.

While the authors have not examined how representation in the discipline affects women in legislative politics outside of academia, Schwindt-Bayer said it could mean less attention to issues that are important to women involved in the legislative process.

So what can be done? Schwindt-Bayer and her fellow authors said a more expansive definition of legislative studies, embracing the diversity of women in the field, peer mentoring and space for women studying legislatures to engage in professional development and share research would be a good place to start.

“This could help encourage more women to join this field,” she said.

The paper is online at https://www.cambridge.org/core/journals/ps-political-science-and-politics/article/women-in-legislative-studies-improving-gender-equality/40661FE6B0FB4E3B8F341DBC6359C2FE.

COVID-19 case studies offer insights into what it will take to combat misleading medical information online

Health care leaders ‘take a shot’ at addressing viral medical rumors and disinformation

Peer-Reviewed Publication

AMERICAN COLLEGE OF PHYSICIANS




1. COVID-19 case studies offer insights into what it will take to combat misleading medical information online

Health care leaders ‘take a shot’ at addressing viral medical rumors and disinformation

Abstract: https://www.acpjournals.org/doi/10.7326/M23-1218    

A team of medical and public health leaders from the American Board of Internal Medicine, ABIM Foundation, and several respected institutions say COVID-19 case studies, among other examples, can inspire new recommendations aimed at combatting viral medical rumors and false or misleading information online. According to lead author, Richard J. Baron, MD, ABIM President and CEO, this issue is particularly important considering the recent judicial opinion prohibiting the federal government from influencing social media companies. The analysis and recommendations are published in Annals of Internal Medicine.

U.S. Food and Drug Administration Commissioner Dr. Robert Calif has called medical misinformation “the leading cause of preventable death in America” and Surgeon General Dr. Vivek Murthy has sounded the alarm, as well.  At no time was this issue more obvious than during the COVID-19 pandemic. ThisIsOurShot and VacunateYa, or TIOS-VY, are linked national grassroots organizations that empower and support trusted medical professionals to share accurate health information on social media and combat misinformation with the goal of building healthier communities. The viral vaccine-selfie movement #ThisIsOurShot was one of their signature efforts. TIOS-VY built the organizational infrastructure to support medical professionals as they engaged and convened online communities. But despite their efforts, nearly 2 years into the pandemic, 78 percent of adults either still believed or were unsure of whether to believe at least 1 of 8 false statements about COVID-19 or COVID-19 vaccines.

TIOS-VY encountered several challenges that hampered its effectiveness online. These included limited funding, limited data about their digital audience, and online harassment and attacks aimed at public health communicators. Considering these challenges, the authors recommend the creation of a sustainably funded, independent public–private partnership to address the challenges faced by TIOS–VY. The authors argue that this structure will allow for sustainable, long-term funding, support for under-resourced stakeholders or members facing online harassment, flexibility in detecting and responding to rumors while protecting vulnerable personal data and could more effectively work with social media platforms to combat misinformation than existing information stakeholders. They believe a fully funded and coordinated response could have a meaningful effect on the nation’s health.

 

Media contacts: For an embargoed PDF, please contact Addison Dunlap at adunlap@acponline.org. To speak with the corresponding author Richard J. Baron, MD, please contact John Held at JHeld@ABIM.ORG.

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2. ACP Calls for Modernizing Public Health Infrastructure

Abstract: https://www.acpjournals.org/doi/10.7326/M23-0670    

Editorial: https://www.acpjournals.org/doi/10.7326/M23-1455    

It is imperative to augment and enhance the public health infrastructure in the United States for it to achieve its mission of preventing illness and promoting health, says the American College of Physicians (ACP) in a new policy paper published in Annals of Internal Medicine. The new paper updates recommendations ACP made in 2012 for the U.S. public health infrastructure with new policies on establishing federal public health leadership, protecting public health workers, reversing workforce shortages, and the need to integrate primary care and public health.

ACP recommends that the U.S. Department of Health and Human Services (HHS) designate a new public-health official who would coordinate interagency work and be responsible for public health efforts. It recommends immediate action from Congress to provide sufficient and stable funding for public health at the federal, state, and local levels. The paper also calls for action to address the severe shortage of public health workers. The number of public health workers employed by state and local governments declined by 15 percent from 2011 to 2021, and a survey of state and local public health found that 27 percent of workers intend to leave their position within a year.

ACP’s paper calls for increased efforts to combat health-related dis- and misinformation, especially through social media platforms. The paper recommends the development of a national public health data system that would be capable of sharing real-time information back and forth between public health departments, physicians, hospitals, laboratories and others. Finally, ACP encourages collaboration between public health and primary care.

In an accompanying editorial also published in Annals, Sherri A. Berger, MSPH and Rochelle P. Walensky, MD, MPH reflected on ACP’s paper from the perspective of the Centers for Disease Control and Prevention (CDC).  In the piece they say the CDC, and their state and local public health partners, are heeding the call to take concrete action, and they further caution that the CDC cannot act alone, and, without funding, flexibility, and new authorities.

 

Media contacts: For an embargoed PDF, please contact Addison Dunlap at adunlap@acponline.org. To speak with someone from ACP, please contact Jacquelyn Blaser at jblaser@acponline.org.

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Also published in this issue:

Moving Naloxone Over the Counter is Necessary, but Not Sufficient

John C. Messinger, MD; Leo Beletsky, JD, MPH; Aaron S. Kesselheim, MD, JD, MPH; and Rachel E. Barenie, PharmD, JD, MPH

Medicine and Public Issues

Abstract: https://www.acpjournals.org/doi/10.7326/M23-0852

National study aims to assist water utilities


UTA civil engineer leads efforts to aid water utilities in monitoring assets

Grant and Award Announcement

UNIVERSITY OF TEXAS AT ARLINGTON

Mohammad Najafi 

IMAGE: MOHAMMAD NAJAFI view more 

CREDIT: UT ARLINGTON




A University of Texas at Arlington civil engineering researcher is leading a nationwide study to find and assess innovative technologies for monitoring water assets.

Mohammad Najafi, associate professor of civil engineering, is using a $410,000 grant from the Water Research Foundation for the project.

“We hope to streamline water asset monitoring so water utilities can make timely decisions and optimize their maintenance activities,” Najafi said. “We will investigate the utilization of existing and innovative asset-monitoring technologies—such as drones, sensors, fiber optics and more—for both horizontal and vertical assets. Considerations for both large and small water utilities will be given.”

Other water entities involved in the project include DC Water, Los Angeles County Sanitation Districts, CDM Smith, Dallas Water Utilities, Greater Cincinnati Water Works, Dallas County, Tarrant Regional Water District, WaterOne, American Water, WSSC Water, Great Lakes Water Authority, Orange County Utilities, San Diego County Water Authority and Underground Infrastructure.

Vinayak Kaushal, assistant professor of civil engineering, will serve as co-principal investigator. Zahra Borhani, program manager at the Center for Underground Infrastructure Research and Education (CUIRE), and Diego Calderon, a doctoral candidate, are part of the UT Arlington team for this project. Najafi leads CUIRE, a research, education and outreach organization that is part of UT Arlington’s Department of Civil Engineering. Since its inception, it has focused on assembling exceptional and broad-reaching engineering and technical talent to address the needs of underground infrastructure on regional, state, national and international scales.

The project will perform a comprehensive literature review on the topic, hold conferences and webinars among water utilities and industry leaders, provide case studies of what is available and make recommendations and guidelines on what to use in the future. Najafi will look at above-ground water infrastructure like reservoirs and dams, as well as below-ground infrastructure like pipes and mains.

Najafi said the project will identify gaps in water utility monitoring and make recommendations to fill them.

“Water monitoring now consists of using sensors, drones, fiber optics and advanced metering infrastructure. Other technologies are on the market and currently being used, but not by everyone,” he said. “We hope to issue a best practices guideline for water entities.”

Melanie Sattler, chair of the Department of Civil Engineering, said Najafi’s project will give water entities better information now and in the future.

“Water monitoring is essential to providing the resources needed for life and growth. This project does just that,” Sattler said. “Knowing how much water you have is vital to planning for the future.”

Bacteria discreetly dwelling in throat revealed to be primary source of Strep A transmission


Breakthrough research has found that Group A Streptococcus (GAS) infections are more likely transmitted from asymptomatic throat carriage than skin-to-skin contact in communities with high rates of infection.


Peer-Reviewed Publication

THE PETER DOHERTY INSTITUTE FOR INFECTION AND IMMUNITY

Maximum-likelihood phylogeny of 320 whole-genome sequences of Streptococcus pyogenes 

IMAGE: MAXIMUM-LIKELIHOOD PHYLOGENY OF 320 WHOLE-GENOME SEQUENCES OF STREPTOCOCCUS PYOGENES view more 

CREDIT: DOHERTY INSTITUTE



Breakthrough research has found that Group A Streptococcus (GAS) infections are more likely transmitted from asymptomatic throat carriage than skin-to-skin contact in communities with high rates of infection.

This major discovery has far-reaching implications for public health approaches, vaccine development and future research as it challenges previous understanding of how the bacterium is spread.

GAS (Streptococcus pyogenes), commonly found on the skin and in the throat, can cause infections ranging from sore throats and impetigo (skin infections) to deadly bloodstream infections. In places like remote First Nations communities where the pathogen is widespread, constant exposure to GAS can lead to severe and life-threatening conditions such as rheumatic heart disease.

In this study, published in the journal The Lancet Microbe, the team of scientists shed new light on GAS transmission dynamics in high-risk settings where the bacteria are prevalent, to inform the development of more effective strategies for prevention and control.

Researchers, led by the Peter Doherty Institute for Infection and Immunity (Doherty Institute), in collaboration with Menzies School of Health Research and Telethon Kids Institute, analysed the genetic makeup of hundreds of GAS bacterial samples collected 20 years ago from throats and impetigo lesions in remote First Nations communities in the Northern Territory, Australia.

Lead author Dr Jake Lacey, a University of Melbourne researcher at the Doherty Institute, explained that genome sequencing played a pivotal role in determining the contribution of impetigo and asymptomatic throat carriage to GAS transmission.

“Our analysis revealed direct connections between isolates recovered from the skin and throat, challenging common thinking that skin-to-skin contact is the primary mode of transmission. In fact, we found that bacteria found in the throat of people who are not showing any symptoms of infections were the likely source of infection in 63 per cent of cases,” Dr Lacey explained.

Professor Bart Currie, from the Global and Tropical Health Division at Menzies School of Health Research, said that these insights provide valuable clues for better controlling skin infections in remote communities, where limited knowledge of bacterial transmission had posed challenges until now.

“With this new genome knowledge we have been able to map out the spread of the bacteria within and between households. This transmission mapping exercise is particularly important for addressing the disproportionate burden of GAS infections on First Nations Australians in remote communities," Professor Currie said.

The Royal Melbourne Hospital’s Professor Steven Tong, Infectious Diseases Physician at the Doherty Institute and senior author of the research paper, underscored the implications of the findings.

“Our research suggests that public health approaches should not solely focus on skin infections but also consider the role of throat carriage in GAS transmission. For instance, vaccines targeting bacteria in the throat may offer greater efficacy in preventing the spread of infection compared to those that only target disease,” Professor Tong said.

“The burden of GAS infection documented in this study also reiterates the fundamental role of primordial prevention in First Nations health initiatives.

“Importantly, this work also prompts researchers to now consider the importance of throat carriage when assessing the transmission dynamics of GAS.”