Deirdre compares her body odour with raw onions. Deepak describes his favorite aftershave as foul-smelling, while Julie says coffee smells like cleaning products.
Covid-19's most common symptom is loss of sense of smell or anosmia. This may last several weeks or even months. People who are able to recover from the condition develop parosmia or a disorienting sense of smell. This can cause things that used to smell pleasant to smell bad or rotten.
Covid-19 is not the only reason. Head injuries, other infections, and even suicide can all trigger it. However, Sars-CoV-2 seems to be particularly adept at triggering this sensory confusion. A recent international survey found that about 10% of people with Covid-related nosebleeds experienced parosmia within the first few days. This number rose to 47% when they were questioned again six to seven months later.
The researchers estimated that there could be 7,000,000 people with parosmia worldwide based on current infection rates.
This is on an unprecedented scale, according to Dr Duika Burges Watson, Newcastle University's researcher who studies the psychological effects of parosmia.
It is not a simple problem. Watson says that it can have a significant impact on your quality life. This includes how you eat, how you interact with others and whether or not you feel safe leaving your home.
Lesley Matthews (52), of Bolton lost her senses of smell in January after she was exposed to Covid-19. It began to return in August. However, most foods and toiletries smell strange to her. Two main distorted smells are what I experience. The first is a chemical-type odor that is found in most toiletries. She says that all fragrances and aftershaves emit the same unpleasant smell, making it difficult for shoppers to tolerate.
This second smell is something I can only compare to the horrible stench of baby's nappies. This smells of all meats, cooked and uncooked, as well as anything that is toasted, roasted, or fried.
Lesley is allergic to many foods. She has been restricted to eating only a few safe foods like porridge, poached salmon and grapes. Lesley feels nauseated as soon as someone turns on the toaster. She says she can't go to a coffee shop and that it is not a pleasant experience for her.
Parosmia patients are more likely to restrict their eating habits and lose weight. Watson states that this is common.
Alternate perceptions of body odour are also common. Watson says that this can cause a loss in social intimacy. There have been cases where people felt they needed to part ways with their partners due to their inability to stand the smell of them. How can you tell someone you love that they find the smell of their partner disgusting?
She recently came across a case in which a person with parosmia had been triggered by the scent of fresh air. They couldn't move from one room to the next in their house. They could smell the stench of the air when they went outside.
Scientists are starting to unravel the molecular mechanisms behind parosmia. This could lead to improved treatment.
A thin membrane covering the nasal cavity is located about 7cm below the nostrils. It's covered with specialised cells known as olfactory sensor neurons. These cells capture odour molecules in the air we breathe and send them to the brain, which processes smell.
These neurons can be damaged by infections such as Covid-19. Current theory holds that neurons can become miswired and signalled in a disordered manner as they grow, leading to parosmia.
Chrissi Kelly, the founder of AbScent smell loss charity, has suffered from parosmia ever since she was diagnosed with a sinus infection in 2012. This is when people report strange smells they cannot describe and are hard to pinpoint.
Although triggers can vary from one person to another, many of the same substances are common: chocolate, coffee, meat, onion and garlic, as well as shower gel, toothpaste, and shampoo.
Research by Jane Parker, University of Reading, and her colleagues are beginning to shed light on the reasons these substances can be so dangerous. Recent experiments involved breaking down the coffee aroma into its molecular components and running them under the noses both parosmia patients and unaffected volunteers.
It was shown that parosmia does not depend on one's ability to smell. There are compounds that can evoke disgust in people suffering from parosmia, but they are pleasant to unaffected people. Although many compounds contain sulphur and nitrogen, not all of them are triggers. These compounds are also easily detected by the human nose in very low concentrations.
Unaffected coffee drinkers described 2-furanmethanethiol as a trigger for coffee. It was described by unaffected participants as smoky, popcorn-like, and the most common. Parker says that many people with parosmia described it as "new coffee". This is how their coffee smells now. Some people described it as horrible and disgusting. It's the most disgusting and horrible smell they have ever experienced.
It is possible that people don't imagine the unpleasantness they feel, because there are a set of common triggers. This supports the miswiring hypothesis. However, if it is happening, it does not seem to be random. Future treatment may be informed by further research to determine the reasons these triggers cause such strong parosmic responses.
Watson suggests that parosmia sufferers make a list of their triggers, and post it where other family members can see it. This will help them to avoid or find alternative substances. Parker and her colleagues discovered that many compounds are formed during the chemical reaction that gives roasted or fried foods their distinctive flavour. The same food might be less offensive if you use different cooking methods.
Unanswered is the question of how long people who have recovered from Covid-19 will be able to expect their parosmia. Parker states that people who had it before Covid took anywhere from six months to two to three years to recover.
Kelly says that while some objects might not smell exactly the way they remembered, it doesn't mean that their quality of living will suffer. Kelly says that you must look for healing and a way to live a life that makes you happy about your daily experiences. This is the only way to recover.
