The coronavirus juggernaut is exactly that, merciless and destructive. The pandemic just refuses to be tamed or slowed down. The social, economic and clinical complexities keep evolving by the day. Each new day brings incremental information on the new virus. Launched from Wuhan, it put the fear of God in northern Italy, and today the United States has become epicentre of the pandemic. Johns Hopkins University suggests that the United States has the world’s largest numbers (more than 82,000 of Covid-19 cases) with about 1200 deaths, giving a case fatality ratio of 1.5%. Globally there are more than 500,000 cases now. India has announced more than $ 23 billion economic stimulus plan for the millions of people affected by the largest lockdown in the world. Mercifully number of deaths so far are relatively less than other nations. Even as I write the UK prime minister Boris Johnson has tested positive for Covid-19. He has fever accompanied by persistent cough, and shall self isolate in Downing Street. In his own words: “I have developed mild symptoms of the coronavirus that is to say a temperature and a persistent cough…stay at home , protect the NHS and save lives.” Luckily for him he manages the short 2 minute video recorded message without a sniffle, sneeze, or a cough.
We know from Chinese data of 1099 confirmed patients the most common symptoms are fever ( 44% on admission and 89% during hospitalisation) and cough (68%). The median incubation period was 4 days. Another Chinese of 99 confirmed cases reported fever in 83% , cough in 82%, and shortness of breath in 31%. A few patients presented with muscle ache (11%), confusion (9%) sore throat (5%) and even chest pain (2%). Yet another retrospective analysis of 191 severely ill patients found that 94% patients had fever, almost 80% had cough, while 15% had muscle pain. An observational study of 36 children published 2 days ago reports that almost half of the children (mean age 8 years) were either asymptomatic or had mild symptoms. Common symptoms at admission were fever (36%) and dry cough (19%). I have presented these observational studies to underscore the commonest symptoms of patients with coronavirus are fever and cough. All studies have one thing in common where symptoms are concerned; a combination of fever and cough.
DOI: 10.1056/NEJMoa2002032
Crucially, no peer reviewed study to date has reported a patient losing the ability to smell or taste. But the world of otolaryngology is today abuzz with the terms “anosmia” and “ageusia,” An otolaryngologist is also known as an ear nose and throat doctor, or an ENT surgeon for short. And just about all of us have visited an ENT doctor at least once in out life time for symptoms ranging from a sore throat to to an ear ache, especially when we were children. Anosmia is the loss of smell, and hyposmia is reduced sense of smell. Smelling things that are not around is phantosmia. Ageusia is the complete absence of taste while dysgeusia is decreased ability to taste. It is important to get the definitions clear because of reports swirling around of a new symptom in coronavirus patients , who complain of loss of smell and even of taste. Anecdotal reports from many patients across the globe infected with coronavirus suffering from anosmia and ageusia have prompted the American Academy of Otolaryngology- Head and Neck Surgery and ENT UK to issue alerts about patients infected with the new coronavirus presenting with only the symptom of altered smell or taste. A detailed joint statement by the presidents of the Rhinological Society and ENT UK has underscored that there rapidly growing number of reports of proven patients infected with coronavirus losing the ability to smell, without any other symptom ascribed to the new virus. A significant number of Covid-19 proven patients have developed anosmia/hyposmia in China, South Korea and also Italy. Germany reports that 2 in 3 confirmed cases have anosmia. South Korea with wide spread testing has almost 30% confirmed positive cases having loss of smell as the major p[resenting symptom. In fact the UK statement documents the occurrence of 4 patients (all under 40 years) with only anosmia as the presenting symptom. But because these 4 patients had no other symptoms they did not merit testing or self isolation. Mention of these 4 patients in this statement becomes problematic because they are not coronavirus confirmed cases. The authors , very senior ENT professionals, are suggesting that anosmia be strongly considered , even if the only symptom, as a marker for Covid-19 infection. A person without fever, without any cough, or muscle pain, but developing sudden loss of smell should be considered a Covid-19 patient. She should be tested and also isolate at least for 7 days. The contacts of such a person should also quarantine themselves for a fortnight. Importantly the association of anosmia with Covid-19 underscores the importance of personal protection (PPE) of ENT surgeons, because they along with intensive care doctors and dentists are very much in the front line.
However it is imperative to appreciate that loss of smell is not an uncommon symptom in the community. A review of more than 5000 patients attending a taste and smell clinic for 4 decades , reported loss of smell in 87% and loss of taste in 62% of these patients. Remember these numbers are not of a community but 5000 people complaining of altered sense of smell or taste, evaluated over 40 years. Moreover these people were suffering from chronic smell and taste dysfunction, and were associated with post influenza type hyposmia and hypogeusia (27%), idiopathic or unknown causes (16%), allergic rhinitis (15%) and subsequent to head injury (14%). The researchers highlight the fact that the senses of smell and taste are vital for a fulfilling life albeit not in the same league as loss of sight or loss of hearing.
The UK ENT statement also clarifies right at the beginning that 40% of anosmia cases are due to viral infection. There are over 200 different viruses that can cause upper respiratory infection like the common cold or a running nose. Therefore it should not come as a surprise that the new coronavirus can affect smell or taste. The UK ENT experts however, based upon global anecdotal reports, warn that people developing sudden anosmia in the absence of other well known symptoms could be carriers of Covid-19, and should be isolated. The WHO so far has so far not added loss of smell or taste in their list of symptoms but are mulling over it. The British experts have been endorsed by the American Academy of Otolaryngology, who urge that anosmia or loss of taste, in the absence of allergies, sinusitis or rhinitis should warrant self isolation and testing. The American Academy recognising that loss of taste has been observed in patients ultimately testing positive for the coronavirus with no other symptom, has proposed “that these symptoms be added to the list of screening tools for possible Covid-19 infection.”
There are a lot of people with altered smell or taste because of reasons already mentioned, and not because of Covid-19. We already have a list of established symptoms in patients with Covid-19 that primarily include over and cough. Anosmia may become a marker in asymptomatic carriers but this will need confirmation in positive cases with Covid-19. To do that we have to start testing as many patients ,with sudden onset of anosmia or ageusia, for the new coronavirus; patients with only have anosmia or ageusia should be compared with a group of people who have absolutely no symptoms. Someone must have designed such a study Loss of smell or taste in a Covid -19 patient is not permanent; it usually resolves in 2 weeks. The mechanism for loss is still unclear; the virus affects the cells in the nostrils to the the olfactory nerve ( nerve of smell). However the insult is quickly rectified by regeneration of new cells.There is little or no taste without smelling. Eating delicious food is actually a combination of smell and taste.
Obviously Mr. Johnson has not noticed so far any alteration in his smell or taste . One should, in his position, retain the the ability to sniff out the best measures to tackle this pandemic, even as scientists across the planet strive to tackle the Covid-19 pandemic.