Triggers for Post-Viral Parosmia

Plain-language summary

Background: Many people lose their sense of smell after they have had a cold, flu or sinus infection. Recovery (if at all) generally starts with a "parosmia" phase which means every-day smells become distorted and over-poweringly objectionable, and this can lead to malnutrition and depression. We do not know much about how or why parosmia happens, but there are key foods common to those who suffer from parosmia which seem to trigger the distortion. Parosmia and COVID-19 Loss of smell has recently been recognised as an official symptom of COVID-19, and we are starting to get reports of people who have recently had COVID-19 developing parosmia. The triggers seem to be similar to those of the common cold, flu or virus infections, but the journey between loss of smell and parosmia is different. Hypotheses 1. Triggers of distortion will be the same for all parosmics. 2. There may be additional trigger foods in different cultures. Questions 1. What are the trigger foods and beverages for parosmia? 2. Are there regional/cultural variations? 3. Does Covid-19 parosmia differ from "standard" post-viral parosmia? The overall aim of the project is to understand the mechanisms involved in parosmia. The approach is to identify foods and everyday aromas associated with parosmia and to determine whether they are the same across different continents/cultures/ethnic backgrounds, and whether Covid-19 parosmia is any different to non-Covid-19 parosmia. The questionnaire will ask about Covid-19 status, ethnic background, smell loss and parosmia, and the changes that occurred between smell loss and parosmia. The participants will then answer questions on up to 15 everyday smells, some of which our preliminary evidence shows are common triggers, and others which are not. The questionnaire will be globally distributed, for example through current collaborations in the UK, US, Germany, Iran, China, Japan and Brazil. It will be completed by participants who are currently experiencing parosmia. All participants will be asked to record any foods that they find distorted and provide a list of aromas which returned undistorted.

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