Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus) disease had first appeared in December 2019 in Wuhan, China and has been spreading quickly throughout the world since then. Since then, the outbreak of this severe viral disease has become a global threat to humanity. An early diagnosis and isolation are the most significant measures required to prevent its spread. Recent anecdotal evidence has suggested oral manifestations with or, without olfactory and gustatory impairment in association with coronavirus disease (COVID-19). Angiotensin converting enzyme-2 (ACE-2) is expressed in oral mucosa in large amounts and can, thus, contribute to the early manifestations of this deadly viral disease. The oral manifestations of coronavirus disease can occur in the form of irregular ulcerative lesions in relation to different parts of the oral cavity and particularly, in relation to the attached mucosa in the hard palate region as well as inflammation and subsequent, atrophy of the various tongue papilla. The associated olfactory and gustatory dysfunction can, also, lead to partial and/or, even a complete loss of the ability to smell and taste in the early stages of the disease onset. Evidence has, also, suggested the presence of SARS-CoV-2 nucleic acid in human saliva making it the carrier of the infectious viral disease as well as aiding in its diagnosis. We have systematically searched medical database for the same and have reviewed all the literature available up to 29th of June 2020.
Oral Manifestations; Olfaction; Gustatory Dysfunction; Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-Cov-2 Virus) Disease; Corona Virus Disease (COVID-19)
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2 virus) is responsible for causing coronavirus disease (COVID-19). Since its outbreak, this deadly, infectious disease has become a serious global threat infecting 1,00,55,037 people worldwide while 4,99,892 deaths have been reported to date. In India alone, 16,095 deaths with 5,28,859 people infected have been reported till date . SARS-CoV- 2 has its roots from Nidovirus family and shares 96.2% genetic similarities with the corona virus found in bats, thus, hypothesized to be possessing a possible zoonotic origin [2,3]. It is, also, postulated that bat corona virus might have undergone Homologous Recombination with some intermediate host and has developed the ability to infect humans. The virus mainly spreads via droplets from an infected patient, but can, also, spread through direct contact and oro-faecal route . Viral genome studies of 103 samples suggest that around 30% of them have infected with S-type while the rest, with L-type subtypes of SARS-CoV- 2 virus . The possible binding of the virus spike protein (a surface glycoprotein) to the angiotensin-converting enzyme-2 (ACE- 2) expressed in the host cells is the major factor in the pathogenesis of the viral disease . This is the reason why the respiratory manifestations are reported commonly amongst the infected hosts as Type 2 pneumocytes present in the lungs express the said enzyme in large amounts, while the infected patients develop pneumonia like symptoms including shortness of breath, dry cough followed by high fever and in later stages, acute respiratory distress syndrome (ARDS) with numerous other secondary complications as multiple organ failure. In addition, upper respiratory manifestations including nasal congestion and sore throat are commonly observed in patients exhibiting mild disease . Since the virus accesses host cells via the enzyme angiotensin-converting enzyme-2 (ACE-2), there has been evidence that the superficial stratified epithelial cells of the oesophagus, absorptive enterocytes from the ileum and colon, cholangiocytes, myocardial cells, proximal tubular cells from the kidneys and urothelial cells from the bladder, also, act as important areas where an active infection can be seen since they all express high amounts of enzyme ACE- 2 . The analysis of public bulk-seq RNA datasets suggest that the mucosa of oral cavity, also, expresses the same enzyme ACE2 found in higher concentrations in the tongue than other oral sites as compared to the gingival tissues and cells of the buccal mucosa and can, thus, lead to active manifestations of this deadly viral disease in the early stages of infection . Therefore, there might be a high probability or, possibility that oral mucosa as well and organs excluding lungs are, also, at risk for secondary sites of infection in the pathogenesis of the disease process. In a mice model, this has been further emphasized based on the observation that SARS-CoV-2 virus can enter via olfactory bulbs, as well . Some of the published literature reports the cutaneous and systematic manifestations of SARS-CoV-2 infection in detail, there is a paucity of data, though, in relation to the oral manifestations of this infectious disease with oral mucosa being a possible source of infection acting as a reservoir for the virus in clinically occult cases. Fewer studies, though, on limited available evidence have reported oral signs and symptoms and olfactory and gustatory dysfunction in the early stages of the disease process prior to the actual symptoms or, even, in asymptomatic cases. Few reports have, also, indicated that oral signs and symptoms can be independent of olfactory and gustatory dysfunction and vice versa or, can manifest simultaneously. The present review is based on a systematic search of the available medical database on similar lines until the 29th of June 2020.