(Bloomberg) -- The coronavirus is capable of attacking key cells in the nose, which may explain the unusual finding that some Covid-19 sufferers lose their ability to smell and taste, Harvard Medical School researchers found.

Their study of human and mice genomic data found certain cells at the back of the nose harbor the distinctly shaped proteins that the coronavirus targets to invade the body. Infection of these cells could directly or indirectly lead to an altered sense of smell, they said in a paper published Saturday.

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Doctors around the world are reporting anecdotal Covid-19 cases in which patients have experienced an abrupt and unexplained total or partial loss of smell and taste. The conditions, known medically as anosmia and dysgeusia, respectively, are “significant symptoms” associated with the pandemic, the American Academy of Otolaryngology, or head and neck surgery, said on March 22.

The group, based in Alexandria, Virginia, proposes that these symptoms be added to the list of screening tools for possible Covid-19 infection. People experiencing the symptoms in the absence of other known causes should consider self-isolation and get tested, the group said.

Inflammation in the nasal cavity triggered by the pandemic-causing infection may hinder the sense of smell, David Brann and Sandeep Robert Datta of the Harvard Medical School’s neurobiology department said. But it’s also possible the virus infects and damages cells in the nasal epithelium required for normal olfactory function.

Uncovering the cause of the sensory loss has important implications to support diagnosis and determine the effects of the disease, the researchers said.

“Furthermore, patients with persistent olfactory dysfunction are at risk of nutritional deficits, of injury due to the inability to smell ‘danger’ odors like smoke, gas and spoiled foods, and of developing psychiatric disorders, particularly depression,” they said.

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