A Review on Ageusia and Anosmia of COVID-19 Infection

Abstract

There is now abundant evidence that loss of sense of smell is one of the most common symptoms of COVID-19 infection and in some cases the only symptom. It is the best predictor of COVID-19 status of all the associated symptoms. Some months after the first reports of the potential value of loss of smell as a diagnostic marker, loss of, or change in, normal sense of smell (anosmia) or taste (ageusia) were included in the UK case definition, allowing patients access to testing and prompting self-isolation.

Keywords: COVID-19; Olfactory and taste disorders; Infection

Editorial

There is now abundant evidence that loss of sense of smell is one of the most common symptoms of COVID-19 infection and in some cases the only symptom. It is the best predictor of COVID-19 status of all the associated symptoms [1]. Some months after the first reports of the potential value of loss of smell as a diagnostic marker, loss of, or change in, normal sense of smell (anosmia) or taste (ageusia) were included in the UK case definition, allowing patients access to testing and prompting self-isolation [2].

In COVID-19, Olfactory and taste disorders (OTDs) are newly testified disorders and have been hypothesized that oral and nasal tissues possibly encompass host cells of SARS-CoV2. Researchers have concluded that hyposmia or anosmia (decrease or loss of smell) and ageusia (loss of taste) is a key indicator that a person who else gives the impression that he is healthy is carrying the virus and possibly be spreading it to others [3].

Olfactory dysfunction is common. Population estimates suggest that 19.1% of adults sufer from loss of smell, a fgure that rises to 80% in patients over the age of 75.4 A meta-analysis reveals that the overall prevalence of alteration of the sense of smell or taste following COVID-19 infection is 47%, ranging between 31% and 67% in severe and mild-to-moderate symptomatic patients, respectively.

In the nose, articulation is seen in both the respiratory epithelium (RE) and the olfactory tactile epithelium (OSE) extensively more significant levels in OSE [4]. There has been a proof of the relocation of infection into the focal sensory system through the nose and olfactory bulbs just as by different routes without attacking the tactile neurons. These olfactory cells comprisse of an early-stage key compound called ACE 2 (Angiotensin Converting Enzyme) [5]. SARS-CoV-2 to get to human cells using this receptor through authoritative with spike protein. Prospective studies on the natural history of anosmia and ageusia and the incidence of long-term sequelae are needed to fully characterize these unique symptoms among COVID-19 patients.

References

1. Borsetto D, et al. Self-reported alteration of sense of smell or taste in patients with COVID-19: A systematic review and meta analysis on 3563 patients. Rhinology. 2020;58: 430-436
2. Bramerson A, et al. Prevalence of olfactory dysfunction: The Skovde population-based study. Laryngoscope. 2004;114: 733-737
3. Hopkins C, et al. Presentation of new onset anosmia during the COVID-19 pandemic. Rhinology. 2020;58:295-298.
4. Menni CVA, et al. Loss of smell and taste in combination with other symptoms is a strong predictor of COVID-19 infection. MedRxiv Preprint Server. 2020
5. Spinato G, et al. Alterations in smell or taste in mildly symptomatic outpatients with SARS-CoV-2 infection. JAMA. 2020;323:2089-2090.