<strong></strong><strong>Anosmia and Ageusia as Initial or Unique Symptoms after SARS-COV-2 Virus Infection</strong>

Abstract

SARS-CoV-2 (CoV-2) is a coronavirus which is causing the actual COVID-19 pandemic. The disease caused by 2019 new coronavirus (2019-nCoV) was named coronavirus disease-19 (COVID-19) by the World Health Organization in February 2020. Primary non-specific reported symptoms of 2019-nCoV infection at the prodromal phase are malaise, fever, and dry cough. The most commonly reported signs and symptoms are fever (98%), cough (76%), dyspnea (55%), and myalgia or fatigue (44%). Nonetheless, recent reports suggest an association between COVID-19 and altered olfactory and taste functions, although smell seems to be more affected than taste. These associations of smell and taste dysfunctions and CoV-2 are consistent with case reports describing a patient with SARS with long term anosmia after recovery from respiratory distress, with the observation that olfactory function is commonly altered after infection with endemic coronaviruses, and with data demonstrating that intentional experimental infection of humans with CoV-299 raises the thresholds at which odors can be detected. Post-viral anosmia and is one of the leading causes of loss of sense of smell in adults, accounting for up to 40% cases of anosmia. Viruses that give rise to the common cold are well known to cause post-infectious loss, and over 200 different viruses are known to cause upper respiratory tract infections. I reviewed the possible mechanisms of smell and taste loss in COVID-19. I concluded that since the existence of such a relationship is likely, it is highly recommended that those patients who experience complications such as smell and/or taste loss, even as unique symptoms, should be considered as potential SARS-CoV-2 virus carriers.

Brainstem Dysfunction in SARS-COV2 Infection Can Be a Potential Cause of Respiratory Distress

“…[75][76][77] It has been widely supported that that lesions in the medulla can cause respiratory dysfunction, like in congenital central hypoventilation syndrome, 78 or severe brain injury, 79 which results in damage to medullar respiratory control function. 35,[80][81][82][83][84] It is extremely important to remark that the brainstem has been severely infected by SARS-CoV34, 35 or MERS-CoV. It has been reported that viral antigens have been detected in the brainstem, where the infected regions included the nucleus of the solitary tract and nucleus ambiguous.…”

“…9-11, 13, 19, 25-34 We have recently reviewed that anosmia and hypogeusia as significant alerting initial or unique symptoms of COVID-19. 35 Curiously, neurotropic and neuro-invasive capabilities have been described in several of their hosts, including humans among them, leading to symptoms such as multiple sclerosis (MS) and encephalomyelitis. A rising amount of evidence demonstrates that neurotropism is one shared feature of CoVs.…”

Olfactory and gustatory dysfunctions due to the coronavirus disease (COVID-19): a review of current evidence

“…Previous studies have shown that the natural origin for SARS-CoV-2 is a bat [2][3][4][5][6]. Coronavirus disease (COVID- 19) is an infectious disease ranging from a mild to more severe respiratory disease, common respiratory manifestations of COVID-19 is dry cough, fever, dyspnea, arthralgia and malaise [2,3], and less common symptoms such as nausea, vomiting, diarrhea and abdominal pain [7], is transmitted by person-to-person [2,3]. However, in several countries such as South Korea, China, Iran and Italy reported taste and smell dysfunctions in COVID-19 infection [1,8].…”

“…Permanent smell disorders are induced by viral upper respiratory tract infections [11]. Current studies among patients show a relationship between COVID-19 infection and smell disorders (hyposmia, anosmia) and loss of taste (ageusia), however, olfactory disorder to be more prevalent than gustatory dysfunctions [2,12]. According to some reports, patients with COVID-19 infection show an entire or little loss of taste and smell [13], without rhinorrhea or nasal obstruction [10].…”

Extrapulmonary Clinical Manifestations in COVID-19 Patients

“…82 It can lead to neurological damage to the CNS which might be followed by anosmia and dysgeusia in COVID-19 patients; anosmia can also be caused by swelling in the nose and sinuses due to chronic sinusitis. 82 Some investigations claim that the proportion of ACE2expressing cells in nasal and oral tissue is comparable to the lung tissue. 83 It has been illustrated that olfactory epithelial support cells, stem cells, and nasal respiratory epithelium express TMPRSS2 and ACE2 genes by which SARS-CoV-2 can enter into them.…”