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Five Questions With: Ford Albritton, MD, on COVID's Loss of Smell and Taste

Ford D. Albritton IV, MD, specializes in the practice of otolaryngology/ear, nose, throat medicine at the Sinus & Respiratory Disease Center at the Texas Institute in Dallas, Tex.

Albritton is researching instances where COVID-19 patients present with anosmia (loss of the sense of smell) and dysguesia (loss of the sense of taste)—and nothing else. These strange facts can be of great diagnostic usefulness to EMTs and other emergency medical professionals as they struggle with coronavirus patients.

EMS World: Anosmia and dysguesia are two of the more esoteric symptoms associated with COVID-19. What makes their presentations in COVID-19 different from losing these senses due to the common cold?

Albritton: Most of the time, when someone feels like they have lost their taste due to the common cold, it is really just a symptom of smell loss. This isn’t the case with COVID-19.

Smell contributes to the ability to differentiate/discern subtle flavors in food and drink. Any impairment to smell can affect flavor discernment and lead to the perceived impairment in taste without ever actually affecting the taste sensors/taste buds. This is the more common form of altered taste as a complaint from patients, as with the common cold.

Loss of taste in its true form means inability to perceive sweet/salty/sour/bitter due to loss of taste bud function or damage to the associated nerves. This is far less common. Again, when most people with a usual cold develop the loss of smell/taste, further questioning shows it is really just a loss of smell. 

This is where COVID-19 is different in its presentation: Patients are losing smell or taste or both. It is a true loss of taste where the bitter taste buds take over, as they appear to be more resilient. 

Additionally, most cases of smell loss with a common cold usually occur with severe nasal congestion and often clear rhinorrhea (runny nose). In COVID-19 cases the smell disturbance often occurs without nasal congestion or drainage. In fact, it may be one of the only symptoms at onset. In 3% of a certain European study’s patient cohort, it was the only symptom.

Why does anosmia and dysguesia occur in COVID-19 cases?

It is as of yet unclear. We have some studies from China that show how COVID affects cell messaging due to the receptor on which it attaches. Specifically, the virus adheres to an important receptor in cell messaging called angiotensin-converting enzyme II (ACE2). 

We are realizing how far-reaching cell messaging is to the function of so many bodily systems. For instance, proteins formed by ACE2 help fight inflammation, relax blood vessels, and reduce oxidative stress. Reduction in ACE2 expression caused by the body’s response to the virus leads to changes in the balance of many other active compounds in the body, leading to increased inflammation/clotting.

One other element of the ACE2 system is the creation of an additional cell messenger called MAS, which is upregulated by ACE2. MAS is highly expressed in the olfactory and lingual epithelium. Its down-regulation may cause the symptom of taste and smell to deteriorate. Presumably, once MAS can return in its functioning, the process reverts to normal/near-normal.

One silver lining of the virus appears to be the increased understanding of how these systems work at the cell messaging level. This may allow us to find new levels of therapy to treat far-reaching conditions.

Are anosmia and dysguesia useful COVID-19 diagnostic tools for EMTs and other healthcare providers?

Yes. Anosmia and dysguesia should be screening questions for any suspected COVID-19 case. The patient’s answers should be communicated to the receiving team at the ER when they are brought in, as it will help delineate a true possible positive case and allow adequate isolation and testing.

About 25%–30% of patients in studies showed decreased smell or taste as their initial or presenting symptom. That said, these studies only enroll patients with mild to moderate infection severity. We do not know if more severe cases had a similar rate.

Meanwhile, 65%–75% of COVID patients questioned had a smell or taste disturbance at some point in their course. This is a large percentage.

What other unusual symptoms signal the possible existence of COVID-19 in a patient, especially when they are not showing common nasal congestion symptoms?

GI symptoms such as diarrhea, anorexia (loss of appetite), and nausea appear frequently. Myalgias, shaking chills, and fevers are also well-recognized features already.

Patients with new-onset stroke symptoms—especially younger patients—should be screened for COVID-19 symptoms. This is because growing reports indicate a hypercoagulable state following virus onset that may lead to stroke or blocked blood flow to extremities. 

What do these unusual symptoms tell us about COVID-19 as a unique disease?

This is a virus that is highly effective at binding to our cells. Not only that, but the place it binds is a critically important receptor in our cells that helps manage very many cellular and systemic functions. This leads to increased contagiousness and potentially severe cell injury in susceptible people.

James Careless is a freelance writer and frequent contributor to EMS World.

 

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