Professor of food science and human nutrition M. Yanina Pepino is a member of the Global Consortium for Chemosensory Research. The group, which includes experts from 38 countries, is gathering data on the loss of smell and taste perception among people with respiratory illnesses such as COVID-19 to determine whether impairment of these senses can predict people who may be carriers.
Photo by L. Brian Stauffer
CHAMPAIGN, Ill. — A significant number of patients who test positive for COVID-19 report a sudden loss of their senses of smell or taste, even when they don't experience the more common symptoms such as a fever, a dry cough or shortness of breath that the U.S. Centers for Disease Control and Prevention advise people to look for.
A global team of more than 500 researchers, including many experts in smell and taste perception, is investigating the abrupt loss of smell and taste – called anosmia and hypogeusia, respectively – in association with COVID-19 and whether these symptoms could help predict patients who may have the disease and could be at risk of being contagious.
"We want to understand whether the loss of smell by itself could be used as a red flag that people should be tested for COVID-19 or should isolate themselves for a couple of weeks to avoid spreading the disease," said University of Illinois at Urbana-Champaign food science and human nutrition professor M. Yanina Pepino.
Pepino is a member of the team, called the Global Consortium for Chemo-sensory Research, which includes experts from 38 countries. Pepino's research explores taste and smell perception in clinical populations.
While much of the attention on COVID-19 focuses on pulmonary symptoms, coronaviruses such as COVID-19 can also invade patients' nervous systems, potentially affecting their peripheral neurological functions such as their sense of smell or taste.
Scientists currently don't know how many COVID-19 patients experience impaired ability to smell or taste, whether both senses are affected or for how long.
Pepino said it will be important to determine how likely it is that the loss of these senses can predict COVID-19 infection.
"With the exception of a handful of recently published studies, much of the information is anecdotal," Pepino said. "Interestingly, we have not heard much about this symptom in patients from Asia, but it has become noticeable in patients from Iran, Europe and now the United States. Between 60% to 80% of COVID-19-positive patients are reporting a complete loss of their sense of smell or taste."
Most people mistakenly think that flavor and taste are synonymous, and when their food becomes flavorless because they have lost their smell sensation – for instance, when they have a bad cold – they erroneously blame it on their taste buds, Pepino said.
"When you're chewing or swallowing, molecules carrying the aroma of the food travel to the back of your mouth and stimulate olfactory receptors in the top of your nose. Both taste and aroma are integrated in your brain and contribute to your perceived flavor of that food," Pepino said.
"Many of us in the chemosensory field think that when patients complain they've lost their sense of taste, it is really a dysfunction of their sense of smell," Pepino said. "However, to be sure, this association with COVID-19 and the loss of taste perception needs to be investigated."
Led by food science professor John E. Hayes of Penn State University, who is also director of the Sensory Evaluation Center, the consortium is inviting people who have recently been ill with COVID-19 or any respiratory disease such as a simple cold or influenza to participate in a survey to examine associations between these respiratory illnesses and the loss of smell or taste.
By conducting the survey online in multiple countries simultaneously, the scientists hope to quickly collect data from thousands of people around the globe.
"The survey, which is translated into multiple languages, will provide us with a quick and powerful global picture of the association between taste and smell loss and COVID-19," Pepino said. "This could be potentially critical knowledge that could help us identify infected patients, flattening the curve at which this virus spreads."
