Cover Letter

Sir, the new coronavirus pandemic was declared a state of public health emergency of international interest by the World Health Organization and, subsequently, called COVID-19 (^{Meng et al., 2020}).

Among the symptoms of this disease, changes in the perception of taste in infected patients, which is also called dysgeusia (^{Giacomelli et al., 2020}), have frequently been observed in early stages.

Along with the causes of dysgeusia, we can mention the correlation with infectious conditions, such as influenza, tonsillitis, and sinusitis, in addition to the relationship with systemic diseases, such as diabetes mellitus. Recently, authors have reported its occurrence as an adverse effect of cancer therapy (^{Hovan, et al., 2010}).

Studies indicate that disorders of the olfactory system may be related to taste disorders in a concomitant way. According to Giacomelli et al., in the Department of Infectious Diseases of Hospital L. Sacco, Milan, Italy, of 88 patients, 33.9 % reported at least one taste or olfactory disorder and, 18.6 %, both. Taste changes were more frequent (91%) before hospitalization. Thus, the report of changes in the perception of taste by patients can be considered the first oral manifestation of SARS-CoV-2 infection (^{Vinayachandran & Balasubramanian, 2020}).

Recent studies indicate the presence of viral load in the saliva collected from most infected patients (^{Sabino-Silva et al., 2020}). Saliva is the main fluid component of the external environment of taste receptor cells (^{Xu et al., 2020}). According to the study by Xu et al., there is a potentiated expression of the angiotensin-converting enzyme 2 (ACE2), responsible for the entry of the virus into the host cell through binding with SARS-CoV-2, in the mucosa of the oral cavity, more specifically in the epithelial cells of the tongue, where there are taste buds, responsible for the identification of flavors.

However, it is important to note that, previously to the diagnosis of dysgeusia as a symptom inherent to the infection of the new coronavirus, clinical condition of xerostomia and other viral or bacterial infections should be investigated, since the quantity and quality of the patient's saliva are also considered factors involved in taste sensitivity (^{Matsuo, 2020}).

Therefore, dysgeusia can be considered an oral manifestation of COVID-19, being an important contribution in the search for resolutions regarding early diagnosis and treatment, in addition to its application in the hospital and laboratory.