Covid-19: A study reveals the causes of loss of the sense of smell during infection

A year and a half after its appearance in Wuhan (China), the virus that causes Covid-19 still has many secrets. In a study published this week and reported by the Pasteur Institute, French researchers have uncovered the mechanisms that cause loss of smell, also called anosmia, that many patients go through at the time of Sars-Cov-2 infection.

Unexplained for a long time, this phenomenon is characterized by different stages. First, it can trigger a viral infection The disappearance of the cilia carried by the sensory neurons., Explains the Pasteur Institute. “However, these same eyelashes allow scent molecules to be received.”

Then the virus was found In sensory neurons. What a provocation Disturbance of the sensory systemWho finds himself ‘Disorganized with Coronavirus infection’. Finally, Sars-Cov-2 enters “In the first brain relay of the olfactory system.”, which leads to The presence of neuritis and viral RNA in several areas of the brain.

Sensory nerve cells such as the olfactory nerve and the olfactory nerve centers in the brain are infected. With the virus, Pierre-Marie Lido, a CNRS researcher and co-author of the study, analyzed in the reported comments By the Pasteur Institute. “Once inside the olfactory bulb, the virus spreads to other nerve structures where it triggers a major inflammatory response.”Co-author Hervé Burhey adds.

To reach this conclusion, researchers from the Pasteur Institute, NRS Center, INSERM, University of Paris and AP-HP conducted a study on patients with Covid-19, and “Completed thanks to analyzes on an animal model”, In hamsters. The results have been published in the journal Transitional Medicine Sciences.

Loss of smell can be prolonged over time. According to our results, loss of smell could persist for several months in some patients.Mark Liquette, co-author of the study, believes. “This persistence of clinical signs is attributable to persistent virus and olfactory inflammation of the mucous membrane.”

One result, according to the Pasteur Institute: “Classic PCR tests using nasopharyngeal swabs may be negative even though the virus persists deep in the nasal cavities.”. Therefore, researchers recommend their implementation Diagnosis by brushing the nose Plus a PCR test In patients with loss of sense of smell..