Anosmia and ageusia associated with coronavirus infection (COVID‑19) - what is known?

Abstract

In 2020 a new pandemic caused by the SARS-CoV-2 coronavirus is affecting the lives of millions of patients and healthcare workers worldwide. The clinical picture of this infection is in a dynamic process of discovery, and more symptoms emerge as the clinicians observe and diagnose manifestations that affect multiple organs. Anosmia (loss of smell), and ageusia (loss of taste) become more frequently cited as independent symptoms or in association with the most common manifestations of the disease, such as fever, cough and dyspnea. A thorough screening program will prevent most nosocomial and community-acquired infections by promoting efficient triage and specific measures such as isolation of the patients. Therefore, it is important to include frequent symptoms in the anamnesis and questionnaires to select those patients who might benefit from testing, isolation, and treatment. This study summarizes the existing data regarding the association of anosmia and ageusia with the SARS-CoV-2 infection. It also aims to describe manifestations of these, particularly in the clinical picture of all symptomatic patients. Health Organisation (WHO) (1). SARS-CoV-2 belongs to the coronaviridae family alongside with SARS-CoV and MERS-CoV, and it has a single-stranded RNA genome (2). The coronavirus invasion of the target cells is mediated by a transmembrane spike glycoprotein (S). It has two subunits: S1, for binding to the host cell receptors, and S2, for the fusion process with the host cell membrane. These subunits will remain in a prefusion conformation after specific protease cleavage, with the distal S1 subunit comprising the receptor-binding domains (RBD), specifically involved in recognition of human angiotensin-converting enzyme 2 (ACE2) (3,4). The S protein will be further cleaved by host proteases and activated for the membrane fusion. Due to the peripheral location of S proteins, they are the main target for neutralizing antibodies and for new developing therapies (3,5). The ACE2 is a functional receptor for the SARS-CoV-2 and has a ubiquitous distribution into the human body, but its expression is higher in the nasal mucosa, lung parenchyma, and gastrointestinal tract (6). Some studies suggest a possible link between smoking and enhanced expression of ACE2 receptors (7), thus, smoking could be a risk factor that increases the susceptibility of the patient to contact the new coronavirus. SARS-Cov-2 is a highly transmissible virus with an incubation period of approximately 14 days, with a median time of 4-5 days from exposure to symptoms onset (8-10). It has been stipulated that the viral transmission is through the droplets, direct contact, contact with an infected individual, fecal, oral, and body fluid routes (11-13). The most typical symptoms experienced by the patients were fever (83-99%), cough (59-82%), fatigue (44-70%), anorexia (40-84%), shortness of breath (31-40%), sputum production (28-33%) and myalgias (11-35%) (14-16). Less common symptoms reported include headache, confusion, rhinorrhea, sore throat, hem...

Physicians’ Perspectives on COVID-19: An International Survey

“…Patients with COVID-19 mild disease might present respiratory or non-specific symptoms like fever, cough, asthenia, myalgia, sore throat, dyspnea, nasal congestion, headache and, to a lesser extent, digestive involvement [ 1 ]. Anosmia and ageusia have also been reported as presenting or sole manifestation [ 14 , 15 ]. Severe pneumonia may worsen to acute respiratory distress syndrome (ARDS) [ 1 ].…”

“…As the SARS-CoV-2 pulmonary invasion is mediated through the ACE2 receptor [ 15 , 21 , 40 ], theoretical concerns about the ongoing angiotensin converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARB) over the COVID-19 prognosis were raised. However, in one study that included 8910 COVID-19 patients, the use of ACE inhibitors or ARBs was not associated with increased risk of in-hospital death [ 21 ].…”

“…The next section comprised questions related to epidemiologic factors related to COVID-19 (questions 7-12). Then, issues related to COVID-19 management were assessed, including disease prevention, diagnosis, and therapy (questions [13][14][15][16][17][18][19][20]. The last part was intended to evaluate perspectives for future therapies as well as which sources are used for medical information (questions [21][22][23][24][25][26][27][28][29][30].…”

[Editorial] 2nd Special Issue: Tackling key immunological and immuno-dermatological pathways and their link to treatment options

“…The review by Tanasa et al (1) entitled 'Anosmia and ageusia associated with coronavirus infection (COVID- 19)what is known?' summarizes the existing data regarding the association of anosmia and ageusia with the SARS-CoV-2 infection.…”

“…The review by Tanasa et al ( 1 ) entitled ‘Anosmia and ageusia associated with coronavirus infection (COVID-19) - what is known?’ summarizes the existing data regarding the association of anosmia and ageusia with the SARS-CoV-2 infection. It also aims to describe these manifestations, particularly in the clinical setting of all symptomatic patients.…”