It was an idea that came out of a virtual cocktail party on Zoom last month between neuroscientist Rachel Herz and some of her colleagues – a test that would detect loss of smell.
“We can’t help ourselves, even though we’re socializing, to start talking about science. So we started talking about this and you know, the light bulbs went off,” said Herz, a Canadian adjunct professor in psychiatry and human behaviour at Brown University in Rhode Island, U.S.
Herz and her two colleagues – Dana Small, professor of psychiatry and psychology at Yale University, and Le Moyne College’s Theresa White – began discussing the connection between the virus and the sense of smell.
“Smell loss seems to be a hidden symptom, often, of COVID-19,” said Herz, referring to reports and articles she’s read since the start of the pandemic.
The reason COVID-19 is so deadly, said Small, a Victoria B.C. native, is the virus’s ability to spread. That spread doesn’t occur so much from the virus staying on surfaces, she explained, but from asymptomatic carriers.
“Now we say asymptomatic because we’re thinking of classic symptoms,” Small said, like coughing, fever, and difficulty breathing.
“But the reports of smell loss suggested that you might have a fraction of people that have smell loss that are otherwise asymptomatic and they could be spreading the disease.”
The three of them came to the conclusion that they needed to create some sort of test that would track a person’s sense of smell. When a person loses that sense, it tends to happen so gradually they don’t even notice it until it’s completely gone.
“So by tracking it over days, you might be able to see smaller declines and that could alert you to the fact that something’s going on,” said Small.
The test is simple: All you have to do is sniff some peanut butter. Rate how strong the smell is. Sniff some vinegar as a measure of control. Record your results.
Repeat this process at the same time every day.
“The reason why peanut butter is the ideal smell to use is because it’s purely activating the sense of smell and not activating this other system, called the trigeminal system, which gives this feel to smell,” explained Herz.
But in the case of vinegar, the trigeminal system is activated.
“If you put vinegar up to your nose and you smell, it’s not just that you have an odour or aroma, you also feel this irritation in your nasal cavity that will make you [make a funny face],” said Small.
Over time, if the scent of the peanut butter is fading away but you’re still feeling that irritation in your nose from the vinegar, it’s a sign that your sense of smell is decreasing.
“If their sense of smell has changed in any significant way,” Herz said, “then they’re alerted and told they need to take further precautions.” This includes self-quarantine and testing, if necessary.
There are also substitutes for peanut butter, such as nut butter and jam. Some substitutes for vinegar include rubbing alcohol and nail polish.
The test is currently in the form of an online survey that is available only to healthcare workers at Yale, as part of a study Small is conducting to see if smell loss can actually identify asymptomatic carriers.
Small said she hopes to release an app that anyone would be able to use but needs funding to continue the study and create the app.
Jasmine Bala
