Tag Archives: circulation

Studies conclude “COVID toes” are unrelated to COVID-19

“COVID toes” are not a sign of COVID-19 infection but a result of sedentary lifestyles linked to community lockdown measures, walking around barefoot at home, and a lack of warm footwear – at least according to two small studies published JAMA Dermatology.

The study from Belgium, led by Dr. Anne Herman, investigated the purplish-red chilblain-like lesions on the feet of 29 patients and the hands of 3 patients of individuals seen at a Brussels dermatology clinic from Apr 10 to 17. They found that COVID-19 is not the cause of these inflammations.

For starters, none of the patients tested positive for SARS-CoV-2, the virus that causes COVID-19, or had antibodies against the virus on serologic testing.

Biopsies of 22 skin samples also showed no evidence of the virus. Twenty of 31 patients (64%) reported mild symptoms characteristic of coronavirus, and 3 (10%) reported contact with a person who tested positive for COVID-19.

Doctors had assumed that COVID-19 is somehow at play, but it turns out that the assumption was not true. So what was the cause?

Nine of 31 patients (29%) had a history of chilblains, and 4 (13%) had Raynaud’s syndrome (discoloration of the fingers or the toes due to changes in temperature or emotional events).

In addition, 64% said they had been less physically active than normal while in lockdown, and most said they remained in socks or barefoot most of the day.

The other study from Spain, led by Dr. Ignacio Torres-Navarro from the University Hospital of la Fe Polytechnic in Valencia, analyzed “COVID toes” in 20 children hospitalized in Spain from Apr 9 to 15 with lesions on the hands and feet.

They had no clinical signs of COVID-19, tested negative on RT-PCR, and had no antibodies against the virus on serologic testing. So again, the coronavirus was not causing the toe injuries.

Histologic testing revealed that the lesions were chilblains. Nine of 20 patients (45%) had a history of Raynaud’s syndrome or chilblains, and 15 (75%) said they walked barefoot around their house during quarantine. Furthermore, only 2 lived in a home with heat.

“Other studies with improved microbiologic tests or molecular techniques aimed at demonstrating the presence of SARS-CoV-2 in the skin may help to clarify this problem,” the authors wrote.

So the symptom does not appear to be caused by COVID-19, but rather by chilblains.

A chilblain is a painful inflammatory condition that results from defective blood circulation on exposure to cold. The skin may first become itchy, then red and swollen with a burning sensation and very tender to touch. An infection may occur should the skin break down. 

Another potential cause is Raynaud’s syndrome: a narrowing of the small arteries that supply blood to the skin in response to cold temperatures or stress.

Having chilblains does not necessarily mean that you have Raynaud’s. However, as both conditions are related to the circulation many people with Raynaud’s also have chilblains. 

The circulation of the Atlantic Ocean plays a key role in the Global Ocean Conveyor Belt. Credit: Intergovernmental Panel on Climate Change.

The Atlantic Ocean’s circulation is at its weakest in 1,600 years, and this could disrupt weather patterns

The circulation of the Atlantic Ocean plays a key role in the Global Ocean Conveyor Belt. Credit: Intergovernmental Panel on Climate Change.

The circulation of the Atlantic Ocean plays a key role in the Global Ocean Conveyor Belt. Credit: Intergovernmental Panel on Climate Change.

The circulation of the Atlantic Ocean plays a key role in regulating the climate on a global level. Scientists have always known that this constantly moving system of deep-water circulation can vary in amplitude. However, a new study is surprising because it suggests the Atlantic’s circulation is at its weakest point in 1,600 years. If this trend continues, it could disrupt weather patterns all the way from the United States to the African Sahel.

The Little Ice Age and modern global warming

The Atlantic’s deep-water circulation is part of a constantly moving system of deep-ocean circulation driven by temperature and salinity, known as the Global Ocean Conveyor Belt. This system carries warm and salty water from the Gulf Stream to the North Atlantic, warming Western Europe in the process. At the same time, the colder water sinks to a great depth, traveling all the way to Antarctica, ultimately circulating back up the Gulf Stream.

Researchers at the University College London investigated ocean-based sediment records and found that the Atlantic’s overturning began to weaken near the end of the Little Ice Age, a cold period that lasted until 1850. It’s possible to know this by studying the size of sediment grains deposited in time by deep-sea currents — the larger the grains, the stronger the current.

According to Dr. David Thornalley, the study’s lead author, towards the end of the Little Ice Age, freshwater disrupted the Atlantic Meridional Overturning Circulation (AMOC) system. As a result, the warm water started melting Arctic sea ice, ice sheets, and glaciers surrounding the Arctic. This provided a huge influx of freshwater into the North Atlantic, making the surface seawater lighter by diluting it, and consequently slowing down the AMOC system.

Using a combination of methods, the results “suggest that the AMOC has weakened over the past 150 years by approximately 15 to 20 percent” said Thornalley.

Given that North Atlantic circulation is much more variable than previously thought, it’s now important for researchers to incorporate the new findings into climate models. It will also prove interesting to learn why previous models have underestimated AMOC decreases so far.

Elsewhere, another study published in the same issue of the journal Nature, by researchers at the Potsdam Institute for Climate Impact Research, Germany, found that AMOC has been rapidly weakening since the 1950s — and climate change seems to be the main culprit. Together, the studies suggest that AMOC is exceptionally weak today.

“What is common to the two periods of AMOC weakening – the end of the Little Ice Age and recent decades – is that they were both times of warming and melting,” said Thornalley. “Warming and melting are predicted to continue in the future due to continued carbon dioxide emissions.”