Although COVID-19 symptoms such as fever, cough, and shortness of breath are well known, the coronavirus has also been found to be linked with other perplexing symptoms: loss of smell and swollen toes (also called COVID toes).
It seems that these strange symptoms happen to be common amongst COVID-19 patients. Up to 80 percent of people who tested positive for COVID-19 have experienced smell or taste loss. About half of the more than 600 total cases on the international registry of skin manifestations, compiled by the American Academy of Dermatology are COVID toes.
How does the coronavirus cause these unusual symptoms?
What Causes Inflammation?
Once the virus enters the body, it initiates an attack on the respiratory systems, mainly the lungs.
As a result, immune cells, called macrophages, pour into the lungs to fight the virus. These macrophages communicate using tiny information proteins called cytokines. Cytokines release signals, and recruit immune cells to the site of infection, and initiate inflammation.
However, with a COVID-19 infection, too many cytokines leak into the bloodstream, causing massive inflammation that breaks down the protective linings of the blood vessels. Inflammation is a prominent feature of COVID-19 and can cause symptoms such as loss of smell or swollen toes according to the location of inflammatory reactions.
The Impact On Nose And Toes
Loss of smell is caused by an inflammatory reaction in the olfactory nerves, which is near the nose. If the olfactory nerves are inflamed from immune cells attacking the virus, it damages the receptors that relay information to the brain. As a result, patients are unable to sense smell.
COVID toes are also thought to be caused by inflammatory reactions within the skin. When immune cells travel to the layer of the skin and cause inflammation, it can cause discoloration in the skin of the toes. Patients with COVID toes report having red or purplish, swollen toes, that look similar to frostbite. COVID toes can be very painful, causing a burning or itching sensation, and can make it difficult for patients to walk.
The Centers for Disease Control and Prevention calls on anyone who is experiencing loss of smell or swollen toes to consult with their healthcare provider and practice self-isolation.
Loss of smell can be the earliest signs of a COVID-19 infection. According to Dr. Carol Yan, University of California, San Diego Health, if a person has smell and taste loss, the person is more than 10 times more likely to have COVID-19 infection than other causes of infection. Therefore, it is best to contact a healthcare provider as soon as possible when experiencing these unusual symptoms.
Sources: NYTimes, Yale Medicine, Stanford, USA Today, NatGeo