Waking up and not being able to smell the coffee could be a sign of <a href="https:\/\/www.who.int\/news-room\/detail\/27-04-2020-who-timeline---covid-19" target="_blank">COVID-19<\/a>, according to\u00a0<a href="https:\/\/see.news\/tag\/dr-magdy-badran\/" target="_blank">Dr. Magdy Badran<\/a>.\r\n\r\nAnosmia, is the loss of the ability to detect one or more smells. It may be temporary or permanent. Anosmia can be due to a number of factors, including an inflammation of the nasal mucosa, blockage of nasal passages, or a destruction of one temporal lobe. The absence of the sense of smell from birth is known as congenital anosmia.\r\n<h4><span style="color: #ff0000">A Marker of COVID-19 Infection<\/span><\/h4>\r\nWhen the novel coronavirus threat emerged in late 2019, the disease was described as atypical pneumonia that presented with symptoms that are also encountered in the common cold or the flu. Fever, cough, and shortness of breath weren\u2019t enough to diagnose the disease clinically, and a test was devised to search for the genetic material from the virus for a positive diagnosis. Since then, doctors observed a variety of unusual symptoms in COVID-19 patients, including heart and neurological symptoms, skin lesions, as well as gastrointestinal symptoms. But the most unusual symptom that has been associated with COVID-19 was the sudden loss of smell (anosmia) and taste.\r\n\r\nThere is already good evidence from South Korea, China, and Italy that significant numbers of patients with proven COVID-19 infection have developed anosmia\/hyposmia. On the other hand, studies based in hospitals and ENT clinics provide valuable evidence where the COVID-19 status and case histories can be determined with more certainty. The first came out of China, where researchers reported a modest 5% of patients had an impaired sense of smell. Studies in France (417 patients), in Italy (202) and in the US (102), on patients all testing positive for COVID-19, found a loss of smell in 86%, 64% and 68% of cases, respectively.\r\n\r\nIn Germany it is reported that more than 2 in 3 confirmed cases have anosmia. In South Korea, where testing has been more widespread, 30% of patients testing positive have had anosmia as their major presenting symptom in otherwise mild cases. In addition, there have been a rapidly growing number of reports of a significant increase in the number of patients presenting with anosmia in the absence of other symptoms.\r\n<h4><span style="color: #ff0000">Post-viral Anosmia<\/span><\/h4>\r\nPost-viral anosmia 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. Previously described coronaviruses are thought to account for 10- 15% cases. It is therefore perhaps no surprise that the novel COVID-19 virus would also cause anosmia in infected patients.\r\n\r\nEveryone will experience anosmia at some point in their life when afflicted by a cold. Whilst the sense of smell usually returns once other symptoms clear, for some people the snotty nose and shivers depart but the lack of smell remains.\r\nThis doesn\u2019t always result in a complete loss of smell. Those affected may be able to still detect certain odours, although the degree of this ability, and the odours themselves, varies from person to person\r\n\r\nPost-viral olfactory loss doesn\u2019t always manifest itself suddenly, but can develop gradually over time. Many of us will get the common cold or a similar virus at least once or twice a year or more.\r\n\r\nPost-viral olfactory loss tends to be more common in females between the ages of 40 and 70, although the reasons for this aren\u2019t clear.\r\n\r\nSpontaneous recovery is the norm for virus-induced anosmia. Even though some animal data indicates that other coronaviruses can destroy the olfactory bulb, so far there are no reports of long-lasting effects in humans. If the sense of smell has not returned a few weeks after recovery, there is a simple behavioural intervention that people can implement: an effective treatment is olfactory training. By simply attempting to smell and identify odours a few times a day over several weeks, people can improve their sense of smell.\r\n<h4><span style="color: #ff0000">Mechanism of Anosmia<\/span><\/h4>\r\nThe olfactory sensory neurons are bipolar and are directly exposed to the environment, which can result in damage from toxic, infectious, chemical, or inflammatory agents.\r\n\r\nThe exact mechanism behind post-viral anosmia isn\u2019t yet understood, but it is clear that the various viruses that cause the common cold, including flu, somehow damage and interfere with the olfactory epithelium. This is the layer of mucous membrane at the very top of the nasal cavity which contains the olfactory receptor cells. A variety of viruses can attack the cranial nerves related to smell or the mucosal tissue that surrounds those nerves. Cranial nerves control things in our head and neck -- such as the nerves that allow us to speak by using our vocal cords, control our facial motion, hear and smell.\r\n\r\nCOVID-19 is just one type of disease caused by a coronavirus. There are many other types of coronaviruses that cause colds and upper respiratory illnesses, as well as rhinoviruses and influenza viruses. Any of these viruses are known to cause inflammation, either directly around the nerve in the nasal lining or within the nerve itself. When the nerve is either surrounded by inflammatory molecules or has a lot of inflammation within the nerve cell body, it cannot function correctly -- and that is what causes the loss or dysfunction of smell. And it can happen to anyone: young and old, healthy and sick.\r\n\r\nTwo possible mechanisms for COVID-19 induced anosmia have been proposed. First, ACE2 receptors, which coronaviruses are known to bind to, are ubiquitous in both the lungs and the olfactory epithelium, and that COVID-19 can damage existing olfactory receptor cells as well as stem cells and other supporting mechanisms.\r\n\r\nSecond, many viruses, including coronaviruses, can propagate via the olfactory nerve and thereby infect and damage the olfactory bulb. Coronavirus RNA has been found in olfactory areas of the brain, and some COVID-19 patients display neurological symptoms. Further research will be needed to confirm the validity of these proposed mechanisms, and there are potentially longer-term psychological effects of this virus still to be understood.\r\n<h4><span style="color: #ff0000">Common Causes of Loss of Smell<\/span><\/h4>\r\nIn the list of the common causes of loss of smell, the first big common cause of loss of smell is the nasal \u2013 sinus disease. The examples of the nasal \u2013 sinus disease consist of allergic rhinitis, which may lead to the inflammation of nasal cavity, chronic sinus infections, which are fungal or bacterial in nature, as well as nasal polyps.\r\n\r\nChronic sinus infections are also known as chronic rhinosinusitis may cause nasal obstruction. That means it may make you feel difficult to breathe through the nose. Then it reduces the sense of smell as well as taste in adults. That\u2019s why it is considered as one of the common causes of loss of smell.\r\n\r\nNasal Polyps are small noncancerous development in the nose and sinuses. That may block the nasal passage. As a result, it causes anosmia.\r\n\r\nSmoking may cause coughing, wheezing, along with sputum production. As a result, it will lead to some disorders, including loss of smell.\r\n\r\nAdaptation is one of the common causes of loss of smell. It is experienced as soon as your olfactory cells are overflown into saturation point with the particular odour molecules.\r\n<h4><span style="color: #ff0000">Self-isolation<\/span><\/h4>\r\nThe World Health Organization recently announced that a sudden loss of sense of smell (anosmia) should be added to the symptoms of COVID-19. An early clue that a loss of smell might be related to COVID-19 came in early March 2020 from a Facebook post about an ear, nose, and throat doctor who suddenly lost his sense of smell. What followed was a gradual accumulation of evidence linking anosmia to COVID-19.\r\n\r\nThe sudden onset of anosmia was described as a new finding that may distinguish COVID-19 from the common cold or flu. The UK government has just done that, stating: \u201cFrom today, all individuals should self-isolate if they develop a new continuous cough or fever or anosmia.\u201d Tens of thousands of cases of Covid-19 may have been missed because of delays in warning the public that loss of taste and smell is a key symptom that should lead to self-isolation or testing.