Loss of smell may be first sign of Covid 19

Researchers have reported that an unexpected loss of the sense of smell may be the first sign a person has the coronavirus.

The American Academy of Otolaryngology — Head & Neck Surgery has proposed adding anosmia and dysgeusia to the list of screening items for potential novel coronavirus disease (COVID-19).

World Health Organization officials have said in a press conference that they are investigating loss of smell and taste as potential early symptoms.

As the virus causes swelling in the olfactory mucosa, it could lead to loss of smell which may be a key clinical indicator in otherwise symptom-free carriers of COVID-19.

It is these 'silent carriers' who may remain undetected by current screening procedures, which may explain why the disease has progressed so rapidly in so many countries around the world," says South Australian specialist Flinders University Professor Simon Carney, from the Southern ENT and Adelaide Sinus Centre.

"While further research is required, loss of smell, or anosmia, has been reported in as many as one in three patients in South Korea and, in Germany, this figure was as high as two in three patients," says Professor of Otolaryngology (head and neck surgery) at Flinders University.

Loss of smell after a vital infection or Post-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.

There is already good evidence from South Korea, China and Italy that significant numbers of patients with proven COVID-19 infection have developed anosmia/hyposmia. In 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.

An ENT professor in London has reported seeing a dramatic increase in patients with anosmia as their only symptom of COVID-19 infection."

As Australia struggles to contain the spread of COVID-10, identification of these carriers could help to slow the spread of infection.

"In the UK, ENT surgeons are pushing to have anosmia highlighted as an important symptom that may signify a patient may be an asymptomatic carrier," says Professor Carney, immediate past president of the Australia and New Zealand Rhinologic Society.

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 – this has been widely shared on medical discussion boards by surgeons from all regions managing a high incidence of cases. Iran has reported a sudden increase in cases of isolated anosmia, and many colleagues from the US, France and Northern Italy have the same experience.

Given the potential for COVID-19 to present with anosmia, and the reports that corticosteroid use may increase the severity of infection, experts advise against use of oral steroids in the treatment of new onset anosmia during the pandemic, particularly if it is unrelated to head trauma or nasal pathology (such as nasal polyps).

Patients should also consider calling their GP with this early symptom as a precursor for possible treatment.