European research reveals how Covid-19 loss of smell different from regular flu

Recent research have revealed that how smell loss associated with corona virus  infection differs from what you typically might experience with a bad cold or flu.The research was conducted at the University of East Anglia by  a European group of smell disorder experts, including the Professor Philpott.

The study published in the Rhinology journal is the first one to compare how people with COVID-19 smell and taste disorders differ from those with other causes of upper respiratory tract infections.

The major differences are found that COVID-19 patients also lose their sense of smell, they can freely breathe as they do not tend to have a runny or blocked nose and they cannot identify the bitter or sweet tastes.

Such findings lend weight to the theory that coronavirus infects the brain and central nervous system.

The research team wish that their work could help in developing the smell and taste tests for speedy COVID-19 screening in primary care and emergency departments.

Prof Carl Philpott, Lead researcher from UEA’s Norwich Medical School, said that, “The loss of smell and taste is a prominent symptom of COVID-19, however, it is also a common symptom of having a bad cold. We wanted to find out exactly what differentiates COVID-19 smell loss with the kind of smell loss you might have with a cold and blocked-up nose.”

The research team carried out The smell and taste tests  were carried out by the team of researchers on about 10 Covid- 19 infected patients, including  10 people with bad colds and on a control group of 10 healthy people, all that matched for age and sex.

“We wanted to see if their smell and taste test scores could help discriminate between COVID-19 patients and those with a heavy cold. We know that COVID-19 behaves differently to other respiratory viruses, for example by causing the body’s immune system to over-react, known as a cytokine storm, and by affecting the nervous system.”, said Prof Philpott.

“So we suspected that patterns of smell loss would differ between the two groups. We found that smell loss was much more profound in the Covid-19 patents. They were less able to identify smells, and they were not able to identify bitter or sweet tastes. In fact, it was this loss of true taste which seemed to be present in the COVID-19 patients compared to those with a cold.”

He also added that this is very exciting because with the help of smell and taste tests we could be able to discriminate between Covid-19 infected  patients and people with a regular cold or flu.

“Although such tests could not replace formal diagnostic tools such as throat swabs, they could provide an alternative when conventional tests are not available or when rapid screening is needed – particularly at the level of primary care, in emergency departments or at airports.

This research also shows that there are altogether different things when it comes to smell and taste loss for coronavirus  patients, compared to those with just a bad cold.

Earlier it was said that the coronavirus affects the central nervous system, based on the neurological signs developed by few patients. There are also resemblance with SARS, which has been reported to enter the brain, possibly through smell receptors in the nose.

“Our results reflect, at least to some extent, a specific involvement at the level of the central nervous system in some COVID-19 patients.”

It is quite interesting that COVID-19 seems to specifically affects the sweet and bitter taste receptors because these are known to play a key role in innate immunity.

“More research is needed to see whether genetic variation in people’s bitter and sweet taste receptors might predispose them to COVID-19, or conversely, whether COVID-19 infection changes how these receptors function, either directly or through a cytokine storm – the over-reaction of the body’s immune system,” said Philpott.


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