Sudden loss of smell and loss of taste - an early symptom of Covid-19 infection

As you are aware, the coronavirus disease 2019 (COVID-19) infection is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The most prevalent symptoms of this infection are fever, cough, shortness of breath, phlegm production, bodyache, joint pain, headache, diarrhea, runny nose, and sore throat.

The spread of the COVID-19 infection in Europe has highlighted a new atypical presentation of the disease- anosmia and ageusia – sudden loss of smell and taste, which may even occur in the absence of nose block. The occurrence of smell dysfunction in viral infections is not new; in fact, many viral infections may lead to temporary loss of smell and loss of taste through an inflammatory reaction of the nasal mucosa, resulting in rhinorrhea or runny nose. However, smell dysfunction linked to COVID-19 infection seems peculiar, as it may not necessarily be associated with runny nose or nose block.

A study was conducted in Europe, involving 417 patients from 12 European hospitals, all diagnosed with mild-moderate Covid-19 infection. The study identified both loss of smell and taste functions as significant early symptoms in the clinical presentation of  the European COVID-19 infection. In their paper published recently, they emphasize the need for the international scientific community, to recognize sudden loss of smell and taste as important symptoms of the COVID-19 infection.

How is this information relevant for us? A highly challenging aspect of Covid-19, besides the fact that it spreads in exponential numbers, is that its carriers do not have Covid-specific symptoms and they would move in the community, totally oblivious of the risk they pose to others. This makes identification and isolation of carriers and those with mild non-specific symptoms very critical for preventing the spread of infection.

Alberta Health Services has not yet adopted the sudden loss of smell and taste as a criterion for availing Covid-19 testing. Nevertheless, we can use it as a simple home-based test to check if our sense of smell is decreasing suddenly, even before it has become prominent enough to cause concern. If we do realize that our sense of smell has been decreasing in the absence of a runny nose or nose block, we could self-isolate for 14 days and protect our family members and the larger community.

- Padmaja Genesh, Learning Specialist at the Alzheimer Society of Calgary