Thursday, August 13, 2020

SARS-CoV-2 droplets travel further and last longer than thought, and even more in humid air

By Dr. Liji Thomas, MD Aug 10 2020

The ongoing COVID-19 pandemic is spread by respiratory aerosols, in which tiny droplets of saliva and mucus containing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are expelled from the upper respiratory tract. Though quite a few studies have investigated the viral load of such droplets, not much is known about how far these droplets move or how long they linger in the air, even though such information is crucial to determining how infectious they are.

Now, a new study by researchers at the University of Twente and University of Rome Tor Vergata and published on the preprint server medRxiv* in August 2020 shows that earlier assumptions about these droplets were wrong. In fact, under 50% relative humidity, the smallest droplets survive 50 times longer, and at 90% relative humidity, up to 150 times longer. In other words, the two-meter or six-foot social distancing rule is grossly inadequate, given the actual advective range of the droplets within one second. And the range, as well as lifetime of the droplet, only increases with smaller droplet size.

Visualisations of droplets in a heavy cough for RH = 50%: a-d, Snapshots of the droplet-laden cough simulation. At time t = 100 ms, the cough contains hot air with high moisture content. The hot moist air propagates (t ~ 200 ms) and dissipates (t ~ 400 ms) into the ambient surroundings. At t ~ 400 ms, we show larger droplets falling out from the puff whereas smaller droplets remain protected and are carried along by the puff.
Preventing Respiratory Transmission

The current rules of social distancing originated with a 1919 paper dealing with the Spanish flu of that time. This, in turn, was based on a theory of droplet transmission of viruses developed by William F. Wells in connection with the spread of tuberculosis. He thought that the wide range of particles produced by a cough or sneeze in a tuberculosis patient would determine the behavior of the droplets. Small droplets would rapidly evaporate and leave behind less infectious dried aerosol particles with lower transmission risk. Larger droplets would be like bullets. In the current study, droplets measuring over 5-10 micrometers are called respiratory droplets and can cause host-to-host spread. Small droplets, or respiratory droplets, transfer the virus through aerosols.

Despite the age of this principle, the evidence is building that it is faulty. Not only has viral spread continued to take place, especially with superspreaders, but the droplets are known to last longer and spread farther than a few seconds and two meters – namely, up to 8 meters and for up to 10 minutes, respectively. This is because droplets are typically expelled as a cloud, within warm and humid air, which delays their drying out and prolongs their infectious period. In fact, droplet lifetime is dependent on the mixing process within this turbulent air, while the earlier drying behavior is that of a single droplet.
Airborne transmission

This change in fundamental assumptions is supported by empirical studies, medical knowledge, and physics – "long-distance airborne transmission through multiphase turbulent droplet cloud emission is an essential factor." Some researchers have shown that very infectious patients may spread the virus in their aerosols over large distances. In fact, the results of such spread may be even more severe disease due to the tiny droplets of the aerosol, which leads to their entry deep into the lungs.

Lifetime ratio for 10 µm and 20 µm droplets: a, Extended lifetime as a function of relative humidity up to RH = 90%. The curves in the figure are fitted according to the function y = a1/(1 − x) + a2, where a1 and a2 are the fitting parameters. Visualisations of humid puff for ambient RH = 50% and 90% at time 600 ms: b, The humid puff maintains coherence for longer time and at much longer distances for larger ambient RH. Note the different humidity color scales for two shown cases.
Humidity and Infectiousness

The current study deals not only with the accumulating nature of aerosols, which remains infectious indoors over hours but also with the little-understood contribution of humidity. Because of the immense difficulty in tracing the movement of thousands of tiny droplets in space and over time, while simultaneously keeping track of or adjusting the conditions such as flow rate, distribution width of the droplets, temperature and relative humidity, the researchers chose to use numerical simulations instead.
Assessing Small Scale Droplet Physics

They tweaked existing methods to ensure that the small scale of the droplet mixing process, as well as the coupling of temperature and humidity, which are so essential to the evaporation of the droplets and thus their lifetime and effects, are properly captured. This involved the development of a very efficient numerical tool that will be of use in revealing the flow physics of an event occurring with breathing, and also what decides the enormous enhancement of the lifetime of a respiratory droplet relative to considering the droplet isolated from its surrounding puff velocity, temperature, and humidity. This tool can also be used to simulate more complicated respiratory events, especially those which take place indoors.

The conditions of the experiment included a duration of 0.6 seconds, simulating a turbulent puff of air into ambient air, full of 5,000 droplets of water, as well as hot air saturated with vapor, in order to replicate a strong cough. The initial temperature was 34 oC. The temperature of the ambient air was set at 20oC, with the relative humidity between 50% and 90%. The heat and vapor in the turbulent puff are exchanged to the ambient air. The researchers tracked the droplets for several seconds to understand the physics underlying their evaporation en masse.

Fall Pattern of Large and Small Particles


The first result at a RH of 50% is the falling out of larger droplets over 100 μm in diameter, in a ballistic manner, because of their weight compared to the airflow, at 0.1 m to 0.7 m from the source. These evaporate faster, compromising the survival of the infectious particles. This agrees with the earliest predictions (Wells, 1930), and the current social distancing guidelines by the World Health Organization (WHO), Center for Disease Prevention and Control (CDC) and the European Centre for Disease Prevention and Control (ECDC).

When smaller than this, however, the droplets form spirals tracing a mostly horizontal path, which means they also promote airborne rather than droplet transmission – unlike the current WHO hypothesis. This is due to their slower settling speed compared to the velocity of the fluid in which they are carried, which means further advection by the turbulent airstream. This latter is essential in airborne transmission of infection.

This small droplet behavior means they have much higher lifetimes than isolated droplets. In fact, 10 μm droplets at RH 50% and 90% have 60 to 200 times the survival times of the Wells value. These move slower related to the fluid flow, and so shrink less due to reduced convection and evaporation.

With successive coughs, therefore, the puff may reach over 2 m from the source at the leading edge, with most of the smaller droplets being in humid surroundings and thus living longer.

Implications and Recommendations


Thus, the study shows that the humidity field around the droplet plus the turbulent velocity, and not just the droplet diameter, determines the respiratory droplet lifetime. This boosts their lifetime by orders of magnitude. The ambient RH further extends the lifetime, and the researchers comment, "This finding may explain why many COVID-19 superspreading events have been reported in indoor environments with large ambient relative humidity." They quote the high spread in meat-processing plants with cooled air, which increases the indoor RH immensely.

This means that aerosol and droplet concentration must be controlled indoors, especially in the coming fall and winter. Again, older medical experts like Soper (1919) are proved right with their claim, originally pertaining to the Spanish flu pandemic of those years, that "there is danger in the air in which they cough and sneeze." Even further, according to the current study, "we must also add "speak," "sing," scream," and even "breath." In fact, Soper recommended open windows at home and work, and masks for suspected patients – an excellent protocol for today at well.

The current study thus confirms and explains Soper's mitigation strategies for use in controlling COVID-19 transmission. The researchers say face masks block respiratory droplets indoors, and some may even reduce the inhalation of these droplets, an essential role for healthcare workers in the pandemic.

Excellent ventilation is equally important to ensure the infectious puff advects out of the room or becomes rapidly and highly diluted. A possible unfavorable effect of this is that good ventilation may increase the length of the propagation path of the droplets, and these two effects of ventilation on transmission properties must be investigated in parallel.

Finally, a lower ambient RH will help speed up the evaporation of the droplets and aerosols, reducing infectivity by decreasing the lifetime of infectious particles and aerosols.

The study sums up, "Our results help to understand why these various mitigation strategies against COVID-19 are successful…. Our present tool and approach will be a starting point for larger parameter studies and for further optimizing mitigation strategies ."
*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.
Journal reference:

Chong, K. L. et al. (2020). Extended Lifetime of Respiratory Droplets in A Turbulent Vapour Puff And Its Implications On Airborne Disease Transmission. medRxiv preprint doi: https://www.medrxiv.org/content/10.1101/2020.08.04.20168468v1

Dr. Liji Thomas
Written by

Dr. Liji Thomas

Dr. Liji Thomas is an OB-GYN, who graduated from the Government Medical College, University of Calicut, Kerala, in 2001. Liji practiced as a full-time consultant in obstetrics/gynecology in a private hospital for a few years following her graduation. She has counseled hundreds of patients facing issues from pregnancy-related problems and infertility, and has been in charge of over 2,000 deliveries, striving always to achieve a normal delivery rather than operative.
Persistent hiccups an unusual COVID-19 symptom


Aug 10 2020
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As the coronavirus pandemic continues to ravage worldwide, new data shows a multitude of symptoms that were not reported previously. It is well-known that the primary symptoms tied to the coronavirus disease are fever, cough, and difficulty of breathing. As time passed by, other symptoms emerged, including the loss of smell and taste, fatigue, body pains, headache, hair loss, and even a rash in the mouth.

Now, a team of researchers revealed another atypical symptom reported by patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes the coronavirus disease (COVID-19) – persistent hiccups.

Study: Persistent hiccups as an atypical presenting complaint of COVID-19. Image Credit: CGN089 / Shutterstock

The case report

Published in the journal The American Journal of Emergency Medicine, a case report by researchers at Cook County Health described an incident wherein a 62-year-old patient who went to the emergency department had reported persistent hiccups for days and an unintentional weight loss over four months.

The man experienced hiccups for four days before being admitted to the hospital due to fever. Further tests revealed the patient had problems with his lung capacity, and he was later isolated and tested COVID-19 infection.

“An abnormal chest X-ray led to a CT scan of the chest with IV contrast, which demonstrated regional, peripheral ground-glass opacities of the upper lobes with small focal ground-glass opacities scattered throughout the lungs,” the authors wrote in the paper.

“He was tested for COVID-19 per admission protocol, started on hydroxychloroquine, his hiccups improved, and he was discharged to home after three days. An emergency medicine physician should keep COVID-19 on the differential and be vigilant of exposure in atypical presentations,” they added.

This is the first case report of persistent hiccups as the presenting complaint in a COVID-19 positive patient, the researchers claimed.
COVID-19 clinical characteristics

The clinical characteristics of COVID-19 are rapidly evolving as data continues to be collected across the globe. As more cases are reported, a multitude of signs and symptoms, even atypical ones, are being reported.

The case report of the man who had hiccups highlights two crucial issues, the researchers noted. First, it underscores the importance of having a detailed evaluation of those presenting with hiccups. Aside from this, it is also important for doctors to take a thorough history, conduct a physical exam, and to obtain general laboratory work and chest X-ray imaging.

Second, doctors and clinicians should keep COVID-19 infection on their differential as more cases are being discovered through atypical symptoms, which could be unexpected and bizarre. Further, doctors and the healthcare team should always maintain personal protective equipment to avoid exposure from patients who do not present with the typical symptoms of the coronavirus infection.

COVID-19 signs and symptoms

The typical signs and symptoms of coronavirus disease include coughing, fever, and shortness of breath, according to the U.S. Centers for Disease Control and Prevention (CDC). As the pandemic evolved throughout the eight months it has rippled across the globe, more signs and symptoms were reported.

These include fatigue, body pain, headache, loss of smell, loss of taste, runny nose or nasal congestion, nausea and vomiting, diarrhea, hair loss, and sore throat. Recently, a new addition has been added, which is the formation of rashes inside the mouth.

In patients with COVID-19, they are to seek medical help if they develop difficulty breathing, persistent pressure or pain in the chest, new confusion, bluish lips or face, and the inability to stay awake. Patients with severe coronavirus illness may develop many complications, including acute respiratory distress syndrome (ARDS), which is life-threatening.
Global situation

The coronavirus pandemic is actively spreading, with the United States reporting the highest number of cases, reaching more than 5 million cases and more than 163,000 deaths. Brazil and India follow with a staggering 3 million and 2 million cases, respectively.

Russia, South Africa, and Mexico report high transmission rates, with cases reaching 890,000, 563,000, and 480,000, respectively. South America has not become the new epicenter of the pandemic, with Brazil, Peru, Colombia, and Chile seeing a surge in infections.
Sources:

U.S. Centers for Disease Control and Prevention (CDC). (2020). https://www.cdc.gov/coronavirus/2019-ncov/symptoms-testing/symptoms.html
COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6

Journal reference:

Prince, G., and Sergel, M. (2020). Persistent hiccups as an atypical presenting complaint of COVID-19. The American Journal of Emergency Medicine. https://www.ajemjournal.com/article/S0735-6757(20)30274-6/fulltext



Written by
Angela Betsaida B. Laguipo
Angela is a nurse by profession and a writer by heart. She graduated with honors (Cum Laude) for her Bachelor of Nursing degree at the University of Baguio, Philippines. She is currently completing her Master's Degree where she specialized in Maternal and Child Nursing and worked as a clinical instructor and educator in the School of Nursing at the University of Baguio.

WHO urges the public to avoid routine dental work amid the coronavirus pandemic


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By Angela Betsaida B. Laguipo, BSN
Aug 14 2020

With the cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) skyrocketing globally, the World Health Organization (WHO) is now warning the public to avoid routine dental procedures to reduce the risk of infection.

In a new interim guidance released by the World Health Organization (WHO), the health agency advises that routine non-essential oral health care, which includes dental check-ups, oral prophylaxis, and preventive care, should be delayed until there has been sufficient reduction in SARS-CoV-2 transmission rates from community transmission to cluster cases.

Considerations for the provision of essential oral health services in the context of COVID-19. Image Credit: Willyam Bradberry / Shutterstock

The WHO recommends that patients who do not need urgent dental care to avoid going to the dentist for the meantime, since the global number of SARS-CoV-2 cases has increased to more than 20.77 million, with at least 754,000 lives lost.

“During the COVID-19 pandemic, effective prevention of oral problems and self-care remains a high priority. Patients should be advised through remote consultation or social media channels on maintaining good oral hygiene,” the WHO said.

Further, WHO said that the guidance also applies to other dental procedures, including those for aesthetic purposes. Online consultations are also encouraged to prevent the risk of community transmission, especially that the pandemic is far from over. However, urgent or emergency oral health care interventions can preserve a person’s oral functioning, to secure one’s quality of life, and to manage severe pain.
Virus spread in oral healthcare settings

Today, health experts have identified high-risk areas where the virus can spread from one person to another. Some locations, where there is a heightened risk of spread, including oral healthcare settings like dental clinics, hospitals, public transportation, and buildings with poor ventilation.

The way SARS-CoV-2 spreads happens through direct, indirect, or close contact with those diagnosed with COVID-19. A person who is infected can spread the virus through respiratory droplets or secretions such as saliva.

In dental clinics, the novel coronavirus can be transmitted by three ways – direct transmission through inhalation of droplets produced by talking, coughing, or sneezing, direct transmission through the exposure of mucous membranes like those found in the eyes, nasal area, or oral mucosa, and through the indirect transmission via contaminated surfaces.

Further, oral health care teams work close to the patients’ faces for prolonged periods. Further, the procedures usually performed involve exposure to many body fluids that may harbor SARS-CoV-2, such as saliva and blood.

Dental practice also involves aerosol-generating procedures (AGPs), which are defined as any medical, dental, and patient care procedure that causes the production of airborne particles, which may contain virus particles.
How to contain SARS-CoV-2 in dental care settings?

To contain the spread of SARS-CoV-2 in dental settings, the WHO urges that dentists only perform emergency or urgent oral procedures. Routine dental care, such as dental cleanings, consultations, and preventive care, should be postponed until the pandemic is over or until there is low COVID-19 transmission.

“Urgent or emergency oral health care may include interventions that address acute oral infections; swelling; systemic infection; significant or prolonged bleeding; severe pain not controllable with analgesia; oral health care interventions that are medically required as a pre-intervention to other urgent procedures; and dental/orofacial trauma,” the WHO said.

The WHO also reiterated that dentists should refer patients if they are in doubt to specialized treatment facilities, since addressing the emergency or urgent care appropriately will prevent the need for them to seek treatment at emergency departments of hospitals, reducing the risk of exposure and freeing up space for those who are seeking COVID-19-related care.

The WHO also provided a rundown of how dentists can go about with the pandemic, without risking their health and the health of others. Dentists should screen patients before the appointment through virtual technology or telephone. Also, they should perform triaging when the patient has arrived in the clinic. Make sure that patients seeking urgent care are catered first, and they do not exhibit the symptoms of COVID-19.

Dentists should also develop a remote assessment of their patients to distinguish those seeking urgent or emergency care. The WHO also underlined the importance of disinfection of the clinic, proper infection control practices, improving the clinic’s ventilation, and the wearing of personal protective equipment (PPE) for healthcare workers.
Source:

World Health Organization (WHO). (2020). Considerations for the provision of essential oral health services in the context of COVID-19. https://www.who.int/publications/i/item/who-2019-nCoV-oral-health-2020.1



Written by
Angela Betsaida B. Laguipo
Angela is a nurse by profession and a writer by heart. She graduated with honors (Cum Laude) for her Bachelor of Nursing degree at the University of Baguio, Philippines. She is currently completing her Master's Degree where she specialized in Maternal and Child Nursing and worked as a clinical instructor and educator in the School of Nursing at the University of Baguio.
Using medieval medicine to find new treatments for modern-day infections

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Interview conducted by Emily Henderson, B.Sc.Aug 11 2020
News-Medical spoke to researchers from the University of Warwick about their research investigating natural antimicrobials and their potential as antibiotics.Thought LeadersJess Furner-Pardoe
Dr. Freya Harrison
Dr. Blessing Anonye

Why did you choose to research infections and their treatment?

Every day we are inching towards a world where we do not have antibiotics that work due to bacterial antibiotic resistance.

It threatens so many parts of modern healthcare, from treating everyday infections to conducting successful surgery and cancer therapies.

We choose to research antibiotic discovery to try and stop this happening.


Image Credit: Kateryna Kon/Shutterstock.com


Why is increasing antibiotic resistance a challenge to scientists?

Bacteria are alive. They respond to the environment and evolve to survive, and their survival is based on beating our drugs. It is like a never-ending battle between our drugs and the bacteria.
How does bacteria’s biofilm make treating infections with antibiotics harder?

There are a few reasons. Firstly, a biofilm acts as a physical barrier that our drugs need to get through.

Secondly, inside the biofilm, the bacteria can share nutrients and resources. Finally, some of the bacteria exhibit a persistence phenotype, which effectively means they ‘go to sleep’. And as a lot of our drugs only work when the bacteria is ‘awake’, these bacteria survive.

Then once the antibiotic is no longer there the bacteria ‘wake up’ and establish the infection again.
What are biofilm-associated infections?

Biofilms are sticky aggregates of bacteria – the individual bacteria cover themselves in a protective matrix of polysaccharides, proteins, and DNA. Although the term ‘biofilm’ is not very well known, everyone is likely to have come into contact with one, as they are really common. It is thought that 75% of human infections have a biofilm established in them.

For example, if you have ever had a cut and it becomes all gooey and yellow – that is a cut where a biofilm of bacteria has made a home. They pose a serious issue in chronic wounds common in diabetic ulcers, or catheter-associated infections.



Image Credit: wirakorn deelert/Shutterstock.com
What are natural antimicrobials and what were they used for?

Natural antimicrobials are things that come from nature and can kill bacteria, fungus, parasites, and viruses. Throughout history, they have been used for a variety of different infections, including infected eyes, cuts and wounds, and malaria.

Although it takes a long time to make sure any drug is safe and effective to use, there are a few examples of natural antimicrobials being used today in modern medicine.

Honey, for example, is used by the UK National Health Service to treat burn wound infections. Another one is the antimalarial drug artemisinin, which comes from the plant wormwood (Artemisia annua).
Can you describe how medieval methods using natural antimicrobials could help fill the antibiotic discovery gap?

We do not have enough potential new antimicrobial drugs in the pipeline and looking into natural products could be a really good source.

Interestingly, many medieval remedies used mixtures of several ingredients, and we think this could be very informative for researchers: perhaps mixtures of different natural products, instead of single molecules, are the key to making more effective preparations.
You reconstructed a medieval remedy known as Bald’s eyesalve to investigate its antibacterial activity. What did you discover?

We have looked at bacteria in two forms, as individual cells (planktonic) and as sticky biofilm communities. Looking at planktonic bacteria is quicker and easier but it is not the most realistic, as when we have an infection the bacteria tend to form biofilms. These biofilms protect the bacteria and make them much harder to kill.

We have shown that Bald’s eyesalve can kill both planktonic cultures and biofilms of different bacteria including S. epidermidis (common in catheter infections), A. baumannii (common in war wounds), S. maltophilia (respiratory infections) and S. aureus (including the superbug MRSA).

The key thing we have shown is that while garlic alone can kill the planktonic bacteria easily, it does nothing against biofilms.

In fact, if you take away any one of Bald’s eyesalve’s ingredients you lose some of the activity against biofilms. This shows that every ingredient is doing something to contribute to the activity against these tricky biofilms.


The Balds Eyesalve mixture in the lab.

Do you believe that by using natural remedies, we could help to tackle the problem of antibiotic resistance?

Most of our current drugs ultimately come from natural sources – mainly plants and fungi. And some of these natural sources have been used in medicine throughout history and in so many different cultures.

While a lot of historical and traditional remedies are likely to be placebos, or possibly even harmful, the fact that some have already led to drug discovery makes it hard to believe that none of the unexplored ones will have any scientific value.

We fully expect some of the remedies to just be folklore or placebo but hope that some of them may be an untapped source of novel antimicrobial mixtures.
Why is it important to look at combining these natural products, as opposed to looking at single compounds?

We are proposing that the mixture is more powerful than one single component. Often natural remedies are divided up into individual parts and tested on planktonic cultures (free-floating bacteria that are susceptible to the environment).

Hundreds of antimicrobial compounds have been identified this way but few of them show good activity against biofilms, and most of the time, compounds that look promising in the lab fail to make their way to the clinic.

Our work has shown that the mixture as a whole is more potent. If we had focused on separating up the mixture, we would have focused on garlic, which when we tested it later on biofilms would not have been active anymore.



Image Credit: Kateryna Kon/Shutterstock.com
What are the next steps in your research into natural antimicrobials?

The two next steps for Bald’s eyesalve are first, to understand exactly what compounds make it antibacterial, and second, to continue our work on checking that this mixture is safe for human use.

We are also working on other natural remedies, and we hope to test these in a similar way to how we have investigated Bald’s eyesalve.
Where can readers find more information?
https://www.nature.com/articles/s41598-020-69273-8
https://warwick.ac.uk/newsandevents/pressreleases/medieval_medicine_remedy
https://mbio.asm.org/content/6/4/e01129-15.short
https://freyaharrison.weebly.com/

About Jess Furner-Pardoe

I am in the 2nd year of my PhD focusing on understanding the chemistry of complex historical remedies.

About Dr. Freya Harrison
I am an Associate Professor of Microbiology at the University of Warwick. My team focusses on understanding the biology of bacterial biofilms in chronic infections and finding new ways to disrupt them.


We are especially interested in making more accurate lab models of biofilms in lung and wound infections, without using live animals, and in using these to explore possible new antibiofilm treatments. I also helped to found the Ancientbiotics consortium, which seeks to study, reconstruct, and test historical infection remedies.

About Dr. Blessing Anonye
I am a Lecturer in Medical Microbiology in the School of Medicine, University of Central Lancashire, Preston, and also a Visiting Research Fellow at the University of Warwick.
I am generally interested in the study of pathogens, antimicrobial resistance, and understanding the gut microbiota in health and disease.


I am particularly fascinated by research on how products from nature could potentially be used as alternatives to traditional antimicrobials.

Europeans could have been infected with syphilis before Columbus set sails to America

Columbus brought syphilis to Europe – or did he? A recent study conducted at the University of Zurich now indicates that Europeans could already have been infected with this sexually transmitted disease before the 15th century. In addition, researchers have discovered a hitherto unknown pathogen causing a related disease. The predecessor of syphilis and its related diseases could be over 2,500 years old.
Syphilis is a sexually transmitted disease - and while commonly dismissed due to the availability of modern treatments, it is in fact spreading at an alarming rate: Over the last decades, more than 10 million people around the world have been infected with the syphilis subspecies pallidum of the Treponema pallidum bacteria. Other treponematoses, such as yaws and bejel, are caused by other subspecies of Treponema pallidum. The origins of syphilis, which wreaked havoc in Europe from the late 15th to the 18th century, are still unclear. The most popular hypothesis so far holds Christopher Columbus and his sailors liable for bringing the disease to Europe from the New World.

Yaws already widespread in Europe

The new study indicates a fair possibility that Treponema pallidum already existed in Europe before Columbus ever set sails to America. The researchers found treponematoses in archaeological human remains from Finland, Estonia and the Netherlands. Both molecular dating of the ancient bacterial genomes and traditional radiocarbon dating of the samples were used to estimate the age of the pathogens causing these diseases. The results indicate that the genomes dated back to between the early 15th and 18th century.
In addition to the syphilis cases, the researchers found yaws in one of the individuals. Like syphilis, yaws is transmitted via skin contact, although rarely through sexual intercourse. Today, the disease is only found in tropical and subtropical regions.
Our data indicates that yaws was spread through all of Europe. It was not limited to the tropics, as it is today."
Verena Schünemann, last author, professor of paleogenetics at the Institute of Evolutionary Medicine of the University of Zurich

Genome of a previously unknown pathogen

 discovered

The research team also discovered something else: The skeleton found in the Netherlands contained a pathogen belonging to a new, unknown and basal treponemal lineage. This lineage evolved in parallel to syphilis and yaws but is no longer present as a modern-day disease. "This unforeseen discovery is particularly exciting for us, because this lineage is genetically similar to all present treponemal subspecies, but also has unique qualities that differ from them," says first author Kerttu Majander from UZH.
Because several closely related subspecies of Treponema pallidum existed throughout Europe, it is possible that the diseases persisted in overlapping regions, and sometimes infected the same patient. The spatial distribution in the northern periphery of Europe also suggests that endemic treponematoses had already spread widely in Europe in the early modern period.

Not just Columbus

"Using our ancient genomes, it is now possible for the first time to apply a more reliable dating to the treponema family tree," says Schünemann. The genetic analyses conducted in this study suggest that the predecessor of all modern Treponema pallidum subspecies likely evolved at least 2,500 years ago. For venereal syphilis in particular, the latest common ancestor existed between the 12th and 16th century.
According to the newly discovered diversity of treponematoses in early modern Europe, syphilis may have either originated or perhaps further developed in the Old World. "It seems that the first known syphilis breakout cannot be solely attributed to Columbus' voyages to America," concludes Schünemann. "The strains of treponematoses may have co-evolved and interchanged genetic material before and during the intercontinental contacts. We may yet have to revise our theories about the origins of syphilis and other treponemal diseases".
Source:
Journal reference:
Majander, K., et al. (2020) Ancient Bacterial Genomes Reveal a High Diversity of Treponema pallidum Strains in Early Modern Europe. Current Biology. doi.org/10.1016/j.cub.2020.07.058.
New catalyst efficiently turns carbon dioxide into useful fuels and chemicals

by Kevin Stacey, Brown University 

AUGUST 13, 2020
Credit: CC0 Public Domain

As levels of atmospheric carbon dioxide continue to climb, scientists are looking for new ways of breaking down CO2 molecules to make useful carbon-based fuels, chemicals and other products. Now, a team of Brown University researchers has found a way to fine-tune a copper catalyst to produce complex hydrocarbons—known as C2-plus products—from CO2 with remarkable efficiency.


In a study published in Nature Communications, the researchers report a catalyst that can produce C2-plus compounds with up to 72% faradaic efficiency (a measure of how efficiently electrical energy is used to convert carbon dioxide into chemical reaction products). That's far better than the reported efficiencies of other catalysts for C2-plus reactions, the researchers say. And the preparation process can be scaled up to an industrial level fairly easily, which gives the new catalyst potential for use in large-scale CO2 recycling efforts.

"There had been reports in the literature of all kinds of different treatments for copper that could produce these C2-plus with a range of different efficiencies," said Tayhas Palmore, the a professor of engineering at Brown who co-authored the paper with Ph.D. student Taehee Kim. "What Taehee did was a set of experiments to unravel what each of these treatment steps was actually doing to the catalyst in terms of reactivity, which pointed the way to optimizing a catalyst for these multi-carbon compounds."

There have been great strides in recent years in developing copper catalysts that could make single-carbon molecules, Palmore says. For example, Palmore and her team at Brown recently developed a copper foam catalyst that can produce formic acid efficiently, an important single-carbon commodity chemical. But interest is increasing in reactions that can produce C2-plus products.

"Ultimately, everyone seeks to increase the number of carbons in the product to the point of producing higher carbon fuels and chemicals," Palmore said.

There had been evidence from prior research that halogenation of copper—a reaction that coats a copper surface with atoms of chlorine, bromine or iodine in the presence of an electrical potential—could increase a catalyst's selectivity of C2-plus products. Kim experimented with a variety of different halogenation methods, zeroing in on which halogen elements and which electrical potentials yielded catalysts with the best performance in CO2-to-C2-plus reactions. He found that the optimal preparations could yield faradaic efficiencies of between 70.7% and 72.6%, far higher than any other copper catalyst.

The research helps to reveal the attributes that make a copper catalyst good for C2-plus products. The preparations with the highest efficiencies had a large number of surface defects—tiny cracks and crevices in the halogenated surface—that are critical for carbon-carbon coupling reactions. These defect sites appear to be key to the catalysts' high selectivity toward ethylene, a C2-plus product that can be polymerized and used to make plastics.

Ultimately, such a catalyst will aid in large-scale recycling of CO2. The idea is to capture CO2 produced by industrial facilities like power plants, cement manufacturing or directly from air, and convert it into other useful carbon compounds. That requires an efficient catalyst that is easy to produce and regenerate, and inexpensive enough to operate on an industrial scale. This new catalyst is a promising candidate, the researchers say.

"We were working with lab-scale catalysts for our experiments, but you could produce a catalyst of virtually any size using the method developed," Palmore said.


Explore further  Researchers make green chemistry advance with new catalyst for reduction of carbon dioxide

More information: Taehee Kim et al, A scalable method for preparing Cu electrocatalysts that convert CO2 into C2+ products, Nature Communications (2020). 

Journal information: Nature Communications

COVID-19 IS NOT JUST A COLD OR THE FLU


Fit and healthy Australians who survived COVID-19 reveal the severe symptoms they still suffer FIVE MONTHS after beating the virus

Young Australians who survived COVID-19 still suffer debilitating symptoms

Amy McKenzieis, 30, still has breathing problems and numbness in her hands

She said she couldn't take a few steps to her front door without blacking out

Anna Liptak, 46, has developed severe fatigue since recovering five months ago

In Australia, people between 20-29 are most likely to contract coronavirus


By ALANA MAZZONI FOR DAILY MAIL AUSTRALIA

PUBLISHED: 13 August 2020

VIDEOS AT THE END

Young Australians who survived COVID-19 are still suffering debilitating symptoms five months after the virus left their bodies.

Amy McKenzieis, 30, said she still suffers daily pain, numbness in her hands and feet, as well as breathing difficulties despite getting over the deadly virus in hospital.

'There hasn't been a day since I had COVID where I have felt normal and myself, and that's been the issue,' she told A Current Affair.

The mother-of-three has been left struggling to breathe and even blacked out.

Amy McKenzieis, 30, (pictured) said she still suffers daily pain, numbness in her hands and feet, as well as breathing difficulties despite getting over the deadly virus in hospital
COVID-19 survivors reveal severe symptoms they suffer MONTHS later

'Now it's a different battle… I've got numbness and tingling in my hands and feet, I've got quite a long of join point. I feel lethargic and have a lot of headaches too,' she said.

Ms McKenzieis said she couldn't take a few steps to her front door without blacking in and out.

'In my age bracket or younger I think a lot of people potentially more invincible because we hear so much about the elderly and the nursing homes - and that's just not the case,' she said.

The young mother said her initial diagnosis was 'extremely scary' and came as a shock.

'When you can't breathe, particularly as a 30-year-old who's normally fit and healthy, that's a terrifying situation,' she said.

'This is a very serious disease. It starts off and very few people to get away with very mild symptoms.

'You're not bulletproofed by being a younger person.'

Marathon-runner Anna Liptak, 46, from Adelaide, still has symptoms five months after contracting the virus at a work conference in Melbourne.

The normally fit and healthy personal trainer said she has spent months confined to her bed with severe fatigue. 


Anna Liptak, 46, (pictured) from Adelaide, still has symptoms five months after contracting the virus at a work conference in Melbourne

'We really don't know what's happening. That's the scary thing. I don't know what's going to happen in the long term,' Ms Liptak said.

'My ears really hurt and often I've got really bad ringing in them to the point that sometimes I feel like I'm going deaf.

'My experience proved that this affects young, old, fit and healthy, and… the long-term side effects are unknown.'

In Australia, people between 20-29 are most likely to contract COVID-19, with almost 5,000 cases and counting.

More than 900 Australian children under the age of nine have been diagnosed with the virus, while 1,774 kids between the age of 10 to 19 have tested positive.

Trump and first lady request mail-in ballots despite attacks


By Kevin Liptak, Abby Phillip and Devan Cole, CNN Thu August 13, 2020


Trump claims funding USPS will lead to ballot fraud 



Washington (CNN)President Donald Trump and first lady Melania Trump requested mail-in ballots for Florida's primary election on Tuesday, according to Palm Beach County records, despite the President's frequent attacks on voting by mail.

The records from the Palm Beach County Supervisor of Elections website show the ballots were mailed Wednesday to Trump's Mar-a-Lago Club, which he made his permanent residence last year.

Despite Trump's rhetoric about voting by mail, the President has recently claimed that Florida's voting system is secure, tweeting earlier this month: "Whether you call it Vote by Mail or Absentee Voting, in Florida the election system is Safe and Secure, Tried and True. Florida's Voting system has been cleaned up (we defeated Democrats attempts at change), so in Florida I encourage all to request a Ballot & Vote by Mail!"

White House deputy press secretary Judd Deere told CNN that "the President supports absentee voting, not universal mail-in voting, which contain several safeguards that prevent fraud and abuse."

Election experts have told CNN there is no real difference between absentee voting and no-excuse mail voting and the two are "essentially the same thing."

USA Today was first to report the ballot request.

Mail-in voting has been front-and-center in recent weeks as fears of the coronavirus have caused states to make the process easier so residents can avoid going to polling centers where infection can potentially spread. Trump and other Republicans have railed against the option, baselessly asserting that it will lead to voter fraud, with the President saying Thursday that he opposes much-needed funding for the United States Postal Service because he doesn't want to see it used for mail-in voting this November.

There is not widespread voter fraud in US elections, and nonpartisan experts say neither party automatically benefits when states expand access to mail-in voting.

But even as Trump publicly opposes mail-in voting, his support of it in Florida and his own decision to use it for the 2020 election could provide Democrats and some Republicans who support the option with yet another argument as to why his opposition to it is purely political.
When the President was asked earlier this month about his support for mail-in voting in Florida, he seemed to imply that Republican-run states with existing mail-in voting programs were up to par, but Democratic states establishing or expanding mail-in voting during the pandemic were not.

"So Florida's got a great Republican governor and it had a great Republican governor (before that) ... and over a long period of time they've been able to get the absentee ballots done extremely professionally. Florida's different from other states," Trump said, before criticizing vote-by-mail efforts in Nevada and New York, states led by Democratic governors.
This story has been updated with a statement from the White House.


CNN's Ellie Kaufman, Marshall Cohen, Jason Hoffman, Nicky Robertson and Betsy Klein contributed to this report.


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Checks In Romania After Beirut Explosion: Ammonium Nitrate Quantity Ten Times Higher Stored In Constanta Port

By Romania Journal Last updated Aug 13, 2020

Almost 26,000 tons of ammonium nitrate are stored in Constanta Port, southeastern Romania, the national Sea Port Administration has announced on Thursday, warning that all operators of dangerous substances must have a security plan approved by the Inspectorate for Emergency Situations.

26,000 tons means a quantity tens time higher than the one stored in the port in Beirut, of around 2,750 ammonium nitrate, which exploded on August 5 and claimed hundreds of lives and leaving thousands injured and homeless.

The Constanta Sea Port Administration has announced that there are currently 25,952 tons of ammonium nitrate stored in the Port of Constanta and that “this type of merchandise is stored in special warehouses certified by the Inspectorate for Emergency Situations.”

According to the above-mentioned sources, 4,908 tons of ammonium nitrate are stored in a certified warehouse at Schenker (Constanța Sud), and they are about to leave for Hungary in the upcoming two weeks. Other 17,521 tones of ammonium nitrate are stored in certified warehouses at Chimpex (northern Constanta Port), while other 3,523 tons are stored at Midia International (the Midia area of the Constanta Port).

The Sea Port Administration also reports that 5 operators are currently carrying out temporary load-download operations for this type of merchandise in Constanta. The administration mentions that all operators handling ammonium nitrate products there are meeting all safety conditions required by ISU, adding that the last ship carrying ammonium nitrate in Constanta Port has been operated on July 17 this year.