COVID-19 is often thought of as a respiratory disease like the flu, but it can affect other parts of the body and have many other symptoms. One of them is loss of the sense of smell and sometimes taste.
An estimated 80 percent of people with COVID-19 have smell disturbances, and many also have dysgeusia or ageusia (a disruption or loss of taste, respectively) or changes in chemesthesis (the ability to sense chemical irritants such as hot chilies). Smell loss is so common in people with the disease that some researchers have recommended its use as a diagnostic test because it may be a more reliable marker than fever or other symptoms.
One lingering mystery is how the novel coronavirus robs its victims of these senses. Early in the pandemic, physicians and researchers worried that COVID-related anosmia might signal that the virus makes its way into the brain through the nose, where it could do severe and lasting damage. A suspected route would be via the olfactory neurons that sense odors in the air and transmit these signals to the brain. But studies have shown that this is probably not the case, says Sandeep Robert Datta, a neuroscientist at Harvard Medical School. “My gestalt read of the data to date suggests 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, predominantly, support cells and stem cells and not neurons directly,” Datta says. But that fact does not mean that neurons cannot be affected, he emphasizes.
Most people recover their sense of smell after a few weeks, but in others it can take months, and it may not come back at all or return with unpleasant effects, like everything smelling of drain cleaner. Yet another reason to social distance and wear that mask!
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