Is the loss of the sense of smell and taste a sign of corona?

The director of the Center for Smell and Taste at the University of Florida answers questions about this trend

[Translation by Dr. Moshe Nachmani]
Doctors from all over the world present cases of corona patients who reported the loss of their sense of smell, known as anosmia, or the loss of the sense of taste, known as ageusia

The director of the Center for Smell and Taste at the University of Florida answers questions about this trend.

Is the loss of the sense of smell a sign of corona?
The loss of the sense of smell occurs during seasonal colds and during other viral infections of the nose and throat. Various reports suggest that the loss of the sense of smell may be one of the first symptoms of the corona disease. Doctors from all over the world report that up to 70 percent of the subjects who were verified as patients with the corona disease caused by the virus COVID-19 - even those without symptoms of fever, cough or other typical symptoms of the disease - suffered from a loss of sense of smell or a loss of sense of taste. An updated study just published found that 20 of 59 patients (aged 74-50) surveyed in Italy reported loss of sense of taste or smell. However, more research is still needed to understand this relationship, but this symptom may provide a cheap and practical early sign for people who will need to self-isolate or be tested more thoroughly, depending on the severity of the symptoms and the availability of tests.

What are Tatarun and Al Tam?
The chemical senses in the human body include smell, which is designed to detect volatile fragrances, and taste, which is able to detect food components such as sugars, salts and vinegar. A number of diseases associated with the chemical sense result from a reduction, disruption or complete loss of the functions of smell or taste. For example, tinnitus is a complete loss or absence of the sense of smell, while almost 13% of people over the age of 40 suffer from a significant impairment in the sense of smell. These levels are lower for young people, but they increase with age. In contrast, loss of the sense of taste is much rarer, and often results from physical damage to the taste nerves. And yet, disorders of the sense of taste and sense of smell are quite common and may negatively affect the health and quality of life of millions of people.

According to news reports, many of the corona patients report a loss of the sense of taste. However, it is more likely that loss of smell is responsible for this symptom. When we eat or drink, the brain combines our perception of taste from the mouth with what is known as sniffing through the nose, that is, the perception of taste resulting from odors emitted from the mouth and entering the nose through the airways in the throat - a phenomenon that becomes what we all know as taste. Patients who have experienced a loss of smell or even a decreased sense of smell may also describe a loss of taste but are still able to detect sugar, salt or vinegar using the taste receptors on their tongue. What they have lost is the effect of smell on their sense of taste. We estimate that in most cases, the loss of taste reported by the corona patients is probably due to a reduced or absent ability to smell.

Why does the corona virus cause chaos?

Loss of the sense of smell (smelling) can result from a large number of reasons such as head trauma, nasal polyps, chronic allergy, exposure to various toxins and neurodegenerative diseases. One of the most common causes of loss or decreased sense of smell is the presence of viruses that cause upper respiratory infections, which we often refer to as 'seasonal colds'. Viruses can affect the sense of smell in several ways - they can attack certain cells in the nasal tissue and thereby cause local inflammation that impairs the ability to detect smells. The virus can disable or directly damage the sensory cells in the nose that detect smells. Another possibility is that viruses can travel along the olfactory nerve pathway through the skull to the brain, where they can do additional damage. Whether this corona virus wreaks havoc on our senses by destroying olfactory nerves, or whether by disrupting their function, this question still remains unanswered, but it will be an important area of ​​research.

Could the loss of the sense of smell be a preliminary sign of the corona disease?

The reports of doctors and patients indicate a high incidence of loss of the sense of smell in corona patients, including many patients without other symptoms. Therefore, testing the sense of smell can be an effective means of identifying people who may be infected with the corona virus. Indeed, a number of otolaryngologists in the United Kingdom and the United States recommend that people who experience a sudden loss of the sense of smell or taste are required to self-isolate for a period of 14 days, and in addition, the test of the sense of smell should be integrated into the detection procedures of the corona patients. However, do the facts support this recommendation? For example, one small study of 59 people found that 60% of patients with upper respiratory tract infections unrelated to the coronavirus experienced a marked reduction in their ability to smell. This finding may imply that the incidence of the loss of smell associated with the corona virus is not higher than the incidence in normal viral diseases.

Unfortunately, an olfactory test is rarely performed as part of a regular visit to a doctor, so there is a lack of information on this topic. In addition, self-reporting of the patient's ability to smell may be inaccurate. Therefore, it is extremely important to conduct controlled scientific studies in order to assess whether disturbances in the sense of smell, such as its complete loss, are indeed preliminary signs of the corona disease. It will take some time to conduct these studies. In the meantime, what should you do if you experience a sudden loss of your sense of smell? The recommendations of the Association of Otorhinolaryngologists of Great Britain seem to be the most reasonable - self-isolation and contact with a treating doctor. The recommendation of the American Academy of Otolaryngologists to include a sense of smell test as part of the diagnostic tests for Corona also sounds logical, even if this test is not absolutely diagnostic. To this end, simple test kits for the sense of smell ('scratch and sniff') for self-use can be sent to the homes of people suspected of having corona, while reporting these results through a secure means of communication, thus reducing the exposure of overburdened medical staff members to the corona virus. Along with measuring the body temperature and reviewing the subject's medical history, a test of the sense of smell could allow doctors to make better medical decisions regarding deciding which of them needs self-isolation or additional tests to diagnose corona.

The news about the subject on the website of the University of Florida