Answers to Go
SAN MARCOS PUBLIC LIBRARY
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Q. Is loss of sense of smell really a symptom of Covid-19?
A. A. Yes, the World Health Organization recognized it as a symptom in April 2020, early on in the pandemic. It is such a strange and distinct feature of COVID-19 that many believe it to be a better predictor of whether someone has COVID-19 than other common symptoms like cough or fever.
Stephani Sutherland, a neuroscientist and science writer for Scientific American stated in her February 2021 article for that magazine that “an estimated 80% of people with COVID-19 have smell disturbances and many also have a (disruption or loss of taste) or a change in the ability to sense chemical irritants such as hot chilies.” Michael Marshall authored an article in January 2021 for Nature online magazine (vol 589, found at https:// www.nature.com/articles/ d41586-021-00055-6) and noted that while the exact percentage of people with a loss of smell varied between studies, most did suggest that smell loss is a very common symptom.
COVID-19 is a disease caused by a virus and a virus is a germ. When a virus enters the body, it attaches itself to healthy cells, injecting them with its own genetic material. This damages the cells and makes the patient suffer such symptoms as difficulty breathing, headaches and fevers. People with strong immune systems are less likely to suffer as people with compromised immune systems, like the elderly or those who have had their systems compromised by prior illnesses. COVID-19 is among the deadliest diseases to have been started by a virus in human history.
But how does COVID-19 affect the sense of smell? That’s still a bit of a mystery, but as the pandemic progresses medical science has answered a little bit of this question. Early in the pandemic, doctors and researchers were worried that COVID related anosmia, the total loss of the sense of smell, might mean that the virus was infecting the odoursensing neurons in the nose that send signals to the olfactory bulb in the brain. There was concern that the virus could access the brain. Obviously, this was of great concern. However, postmortem studies of people who had COVID-19 have shown that the virus very rarely enters the brain. Sandeep Robert Datta, a neuroscientist at Harvard Medical school in the article for Scientific American said that, “My gestalt read of the data suggest that the primary source of insult is actually in the nose, in the nasal epithelium,” the skinlike layer of cells responsible for registering odors. “It looks like the virus attacks, predominately, support cells and stem cells and not neurons directly.” As the article goes on to describe, “Olefactory neurons do not have angiotensinconverting enzyme 2 (ACE2) receptors which allow the virus entry to cells, on their surface.” Sustentacular cells, those that support olfactory neurons, are probably what the virus is attacking. Smell loss occurs when the coronavirus infects cells that support neurons in the nose
The library has ordered quite a few books on COVID-19 and many of them, at the time of this publication, are still on-order because they are newly published. Since the science behind the disease is still being explored, we anticipate many more books will be published and we will order those that will be of use to the San Marcos Library’s community. In the meantime, the library’s copy of Feburary 2021’s Scientific American magazine has a more thorough story on this topic and can be checked out. Much of the information in this column was informed by this article. In addition, two juvenile books are currently in the children’s collection: COVID-19 and other Pandemics: A Comparison by Don Nardo and The COVID-19 Pandemic: The World Turned Upside Down by Hal Marcovitz.
