Losing your sense of smell or taste is one of the clearest signs that a person has contracted the coronavirus. Earlier in the pandemic, many cases abroad in Italy, China, and South Korea involved patients losing their sense of smell or taste. An increasing number of patients started expressing similar symptoms here in the US, and the Centers for Disease Control and Prevention recognized the loss of taste or smell as one of the symptoms associated with COVID-19.
In a recent analysis by The New York Times, nearly 90% of patients reported a loss of taste or smell, according to a study. While symptoms of the coronavirus often resemble those of the common flu, losing your ability to smell or taste is what separates the two viruses.
Patients infected with the virus generally have symptoms such as fever, cough, or shortness of breath, but nearly a quarter of people with the bug said that losing their sense of smell or taste was their only symptom.
When it comes to smell, a new study from India has identified certain odors that are difficult to smell in COVID-19 patients, which might give experts a clearer image of this medical anomaly.
A pilot study published in Medrxiv targeted five odors that are distinctly different in their own right, which makes them easier to identify: Peppermint, fennel, coconut oil, garlic, and cardamon. The study, which is in preprint and has not been peer-reviewed, offered participants an at-home test kit which authors the study said could be a cost-effective test that can be done safely.
“This smell test can be used as a swift-tool for community surveys to detect high-risk pockets in a large population. The odor test will enable self-reporting, early identification, and isolation of asymptomatic/ pre-symptomatic cases or patients with mild symptoms. Thus, the odor test will facilitate targeted mobilization of resources for tracing, testing, and isolation of cases in these areas,” the researchers wrote.
The test was conducted on 49 asymptomatic COVID-19 positive participants and 35 control individuals. After compiling data from the tests, researchers found that asymptomatic patients had trouble smelling two fragrances — coconut oil and peppermint.
Thirty-seven percent of COVID-19 positive participants reported having trouble in smelling peppermint, while nearly a quarter — 22% — said they couldn’t smell coconut. It’s interesting because these two scents are pretty distinct in their own right, with each having its own unique scent.
If you’re wondering how the virus can deactivate both smell and taste, experts from Vanderbilt University said it’s because the virus causes an “inflammatory reaction” inside the nose, which can lead to the loss of smell neurons.
“In some cases, this is permanent, but in other cases, the neurons can regenerate. That’s likely what determines which patients recover. In COVID-19, we believe smell loss is so prevalent because the receptors for COVID-19 that are expressed in human tissue are most commonly expressed in the nasal cavity and in the supporting cells of the olfactory tissue. These supporting cells surround the smell neurons and allow them to survive,” the report said.