Is 'Covid toes' a thing? What the latest study says

  • 'Covid toes' are red bumps or sores that appear on people's toes
  • An uptick in this condition during the pandemic has had doctors scratching their heads
  • A new Spanish study says it has found evidence of coronavirus in these lesions

An uptick in chilblains – also known as 'Covid toes' – has been noticed around the world, afflicting children and young adults.

These small acral lesions on toes normally look like red swollen bumps and are caused by inflamed blood vessels. 

Despite its colloquial name indicating a link to the coronavirus, it is uncertain if this phenomenon is actually caused by the disease. 

Most patients presenting with chilblains test negative for SARS-CoV-2, and less than 50% of cases have a history of respiratory or gastrointestinal symptoms or are related to contact with abrasive household contaminants.

A new study, published in the British Journal of Dermatology, may, however, add some more weight to the argument favouring the coronavirus. 

Virus particles found in cells

Researchers from Spain decided to do a skin biopsy on seven paediatric patients in Madrid presenting with Covid toes to assess whether there was any evidence of the virus.   

The patients ranged between the ages of 11 and 17 years, and three were girls. One patient even had the condition on their hands, elbows and knees, and none had a history of chilblains. All of them tested negative for the coronavirus. 

"Although the clinical and histopathological features were similar to other forms of chilblains, the presence of viral particles in the endothelium and the histological evidence of vascular damage, support a causal relation of the lesions with SARS-CoV-2," write the authors.

READ | More symptoms of coronavirus: 'Covid toes' and skin rashes

No other factors detected

They also noted the chilblains couldn't be a result of cold weather because all of the conditions presented themselves during Spain's mild spring season.

The study theorises that ACE2 receptors are widely expressed in endothelial cells, which is the common gateway for Covid-19 infection. 

"Chilblains seen in young people may, to some extent, resemble the severe acral ischemia caused by thrombosis in severely ill Covid-19 patients."

However, this was quite a small study and electron microscopy was carried out on only one case. 

"More studies are needed  to understand the reasons why previously healthy children, adolescents and young adults present with limited skin forms of Covid-19, in contrast with the severe multi-organ presentations seen in older patients with background diseases," the researchers conclude.

READ MORE | Proof that the coronavirus can infect lab-grown brain cells might make its effects felt long-term

What previous studies say

Some researchers, according to a JAMA Dermatology article, believe that the the uptick could be attributed to a more sedentary lifestyle caused by self-isolation and lockdowns and the fact that people are walking more barefoot in their homes during the day.

Those who have linked 'Covid toes' to Covid-19 did so through indirect causal links like related symptoms, living with someone who has tested positive, or testing positive for antibodies, indicating recovery from the virus. 

One study by Belgian researchers found no traces of the virus in the biopsies of 22 patients' chilblains – a larger study than the Spanish one – and all the subjects tested negative for the coronavirus. 

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Image credit: Jamanetwork

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