Introduction
In December 2019, the Coronavirus Disease 2019 (COVID-19) outbreak emerged in Wuhan, Hubei Province, China and rapidly spread throughout the country and then evolved into a global pandemic (1). On February 12, 2020, The World Health Organisation (WHO) declared that the disease was caused by the novel coronavirus as COVID-19(1). Efficient screening, prompt diagnosis and isolation of the infected individuals were deemed fundamental to contain the outbreak (2).
Several signs and symptoms were observed in some patients including non-productive cough, fever, myalgia, fatigue, dyspnoea, diarrhoea, nausea and vomiting, while other patients were asymptomatic (3). The diagnosis of COVID-19 is based on the clinical suspicion, computerised tomography (CT) findings, and a reverse transcription polymerase chain reaction molecular test (RT-PCR) (3).
The incubation period of COVID-19 is presumed to be between 2 and 11 days, with a mortality rate reaching 2 to 4% (3). The most common peripheral nervous system manifestations of COVID-19 include anosmia (loss of smell) and dysgeusia (taste impairment). Although, most patients gradually regain their sense of smell and taste, the mechanism of these dysfunction is not fully understood (4). Post-infectious olfactory dysfunction is thought to be the result of involvement of the olfactory bulb and damage to the olfactory receptors cells due to the neurotrophic features associated with SARS-CoV-2 (5). Minimal data are available for the mechanism of taste disorders among patients with COVID 19, Single cell RNA-sequencing studies showed that epithelial cells of the tongue express ACE-2 receptors where buccal mucosa may play a role in entry of SARS-COV2. Additionally, indirect damage of the taste receptors through infection and inflammation of the epithelial cells are hypothesised to play a role in the pathogenesis. (6)
A review of the literature showed that the prevalence of anosmia ranged between 22% to 68% (7). Regionally, a study conducted in the Kingdom of Saudi Arabia, reported that the prevalence of olfactory dysfunction, anosmia and hyposmia was 53%, 32.7% and 20.3% respectively. Patients aged 15–39-year-old were mostly affected, and the prevalence of olfactory dysfunction was higher among females (60.3%) compared to males (56.5%) (8). In the same study, the prevalence of ageusia was determined at 51.4% (4). The loss of taste and smell senses is mostly transient lasting between one and two weeks. However, few chronic cases lasting more than one year after diagnosis have been reported.
Few studies explored the impact of anosmia and dysgeusia on patients with COVID-19 and reported negative impact of these symptoms, interference with daily activities and deterioration in well-being (4,9,10). A study conducted in the Eastern region of Saudi Arabia reported that 23% of participants felt isolated, 12.6% reported having problems with taking part in daily activities, anger in 28.2%, difficulty in relaxing in 21% of participants, and worrying about their ability to cope with their changes in sense of smell in 22% (4).
In view of their predominance as signs and symptoms of the disease and in light of their substantial impact on quality of life, there is a need to study the frequency of these two symptoms, establish their association with COVID-19 diagnosis, and whether they are prognostic factors for COVID-19 outcomes.
Objectives : This study aims to estimate the prevalence and risk factors of olfactory and gustatory dysfunction in patients infected with Covid-19 and to investigate their impact on patient’s life.