Does the loss of smell only occur due to Covid-19?

Does the loss of smell only occur due to Covid-19?

Covid-19 causes loss of smell: upper respiratory tract viruses, and conditions like traumatic brain injury, rhinosinusitis, Alzheimer’s, and Parkinson’s disease, can also cause it.

Apart from fever, headache, malaise, cough, and shortness of breath, several patients with Covid-19 report loss of smell or taste, either a continuum or an isolated symptom in an otherwise asymptomatic person. Indeed, loss of smell or taste has become synonymous with a diagnosis of Covid-19: but, does it only occur due to the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection?

In today’s article, we highlight the mechanisms underlying the loss of smell. We also delineate other common causes besides SARS-CoV-2.

The olfactory nerve, the first cranial nerve, is responsible for conveying information about the smell from the nose to the brain at the olfactory neuro-epithelium through the olfactory cleft located in the upper portion of the nasal cavity. When airflow odorants (odour generating substances) reach the neuro-epithelium, they attach onto the olfactory receptor proteins, which are activated and interpret the signal to give the person that particular sense of smell. There are about 5 to 30 million receptor nerve cells within the neuro-epithelium. They express up to 350 various olfactory receptor proteins [1]. It is this variety that enables us to pick every type of smell around us.

Covid-19 isn’t the only illness that can cause loss of smell. Loss of smell is existent in more than 60% of persons with common colds and acute rhinosinusitis [2]. Adenovirus, rhinovirus, coronavirus, and influenza are associated with loss of smell in upper respiratory infections. Traumatic brain injury, neurodegenerative diseases are other major aetiologies. Other causes include tumours within the skull (cranium) or nose and sinuses, drugs, irradiation, et cetera [3].

Related:

Investigations in Covid-19. The Rationale

Inability to smell occurs when impulses along the olfactory nerve are blocked. It can occur due to mucosal inflammation or neurodegenerative changes along the nerve or at the neuro-epithelium. Cells surrounding the olfactory neuroepithelium highly express angiotensin-converting enzyme receptor-2 (ACE2) and transmembrane protease serine 2 (TMPRSS2) [3]. The two proteins enable SARS-CoV-2 to enter the cells, replicate, and cause carnage. The olfactory receptors express them to a lesser extent. It may explain the loss of smell that occurs during Covid-19.

It is imperative to test for Covid-19 if you experience a sudden reduction in the smell pattern with or without constitutional symptoms during this period.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Posts

Health benefits of eating eggs.

Health benefits of eating eggs

Eggs are one of the most nutritious and versatile foods you can eat. They are a reliable source of high-quality protein, healthy fats, vitamins, minerals, and antioxidants that support your health and well-being. In this article, we will explore some of the amazing health benefits of eating eggs and how to include them in your ...

Read More
An african child with mumps seated on a chair. Created by Bing Image creator

Mumps virus infection in adolescent males may cause infertility! Why?

Abstract When someone talks about the Mumps virus, we all remember that time when the cheeks of the neighborhood playmates became painfully puffed up like puffy fish – following an inflammatory response that culminated in the swelling of the parotid glands – Mumps parotitis. However, one of the distinctive features of mumps infection is its ...

Read More
Infant nutrition: An African boy taking porridge.

Nourishing Start: The Importance of Infant Nutrition

Introduction: Proper nutrition during infancy is crucial for babies’ healthy growth and development. This article aims to provide an understanding of infant nutrition, highlighting the importance of breastfeeding, introducing solid foods, and promoting a balanced diet for optimal health outcomes. Breastfeeding: Nature’s Perfect Food Breast milk is considered the gold standard for infant nutrition. It ...

Read More
Enable Notifications OK No thanks