Explained: Why do some coronavirus patients lose their sense of smell? Will it be permanent?

New Delhi, July 31: Losing your sense of smell also known as anosmia was the most commonly reported coronavirus symptom that came to light after it was reported by a number of patients. However, the main symptoms of COVID-19 include fever, a persistent cough and shortness of breath. Now scientists discover why this coronavirus causes some patients to lose their sense of smell and whether it will be permanent.

Losing your sense of smell or anosmia, and sometimes accompanied with loss of taste, is one of the earliest and most commonly reported warning signs of coronavirus..

According to researchers at Harvard Medical School identified which cell types used for smelling are the most vulnerable to a COVID-19 infection.

However, in the new study which was published Friday in Science Advances, the researchers were surprised to discover that those neurons were largely unaffected by the coronavirus, and that the virus "is not actually capable of attacking the neurons that live in your nose,"Associate professor of neurobiology at Harvard Medical School and co-author of the study, Dr Sandeep Robert Datta said.

The study found that the coronavirus was not able to attack the olfactory sensory neurons because they are missing the ACE2 gene that enables the virus to enter human cells.It rather attacks the cells supporting the olfactory sensory neurons.

Datta said this was a positive finding because it suggests most cases of COVID-19 are unlikely to cause a permanent loss of smell.

What is Anosmia?

Anosmia is the partial or complete loss of the sense of smell. This loss may be temporary or permanent. Common conditions that irritate the nose's lining, such as allergies or a cold, can lead to temporary anosmia.

More serious conditions of Anosmia that affect the brain or nerves, such as brain tumors or head trauma, can cause permanent loss of smell. Old age sometimes causes anosmia.

Causes
Nasal congestion from a cold, allergy, sinus infection, or poor air quality is the most common cause of anosmia.

Other causes include:

• Nasal polyps -- small noncancerous growths in the nose and sinuses that block the nasal passage
• Injury to the nose and smell nerves from surgery or head trauma
  Exposure to toxic chemicals
• Certain medications, including antibiotics, antidepressants, anti-inflammatory medication, heart medications, and others.
  Cocaine abuse
• Old age
• Certain medical conditions, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, nutritional deficiencies, congenital conditions, and hormonal disturbances.
• Radiation treatment of head and neck cancers.