How COVID-19 smell loss differs from the common cold
New research from a European group of smell disorder experts, including Prof Philpott at the University of East Anglia, shows how smell loss associated with COVID-19 infection differs from what you typically might experience with a bad cold or flu.
The new study published today is the first to compare how people with COVID-19 smell and taste disorders differ from those with other causes of upper respiratory tract infections.
The main differences found are that, although COVID-19 patients also lose their sense of smell, they can breathe freely, do not tend to have a runny or blocked nose, and they cannot detect bitter or sweet tastes.
These findings lend weight to the theory that COVID-19 infects the brain and central nervous system.
The research team hope that their work could help develop smell and taste tests for fast COVID-19 screening—in primary care and emergency departments.
Lead researcher Prof Carl Philpott, from UEA's Norwich Medical School, said: "The loss of smell and taste is a prominent symptom of COVID-19, however it is also a common symptom of having a bad cold. We wanted to find out exactly what differentiates COVID-19 smell loss with the kind of smell loss you might have with a cold and blocked-up nose."
The research team carried out smell and taste tests on 10 COVID-19 patients, 10 people with bad colds and a control group of 10 healthy people—all matched for age and sex.
Prof Philpott said: "We wanted to see if their smell and taste test scores could help discriminate between COVID-19 patients and those with a heavy cold.
"We know that COVID-19 behaves differently to other respiratory viruses, for example by causing the body's immune system to over-react, known as a cytokine storm, and by affecting the nervous system.
"So we suspected that patterns of smell loss would differ between the two groups.
"We found that smell loss was much more profound in the COVID-19 patents. They were less able to identify smells, and they were not able to identify bitter or sweet tastes. In fact it was this loss of true taste which seemed to be present in the COVID-19 patients compared to those with a cold.
"This is very exciting because it means that smell and taste tests could be used to discriminate between COVID-19 patients and people with a regular cold or flu.
"Although such tests could not replace formal diagnostic tools such as throat swabs, they could provide an alternative when conventional tests are not available or when rapid screening is needed—particularly at the level of primary care, in emergency departments or at airports.
"This research also shows that there are altogether different things going on when it comes to smell and taste loss for COVID-10 patients, compared to those with a bad cold.
"It has previously been suggested that the COVID-19 virus affects the central nervous system, based on the neurological signs developed by some patients. There are also similarities with SARS, which has also been reported to enter the brain, possibly via smell receptors in the nose.
"Our results reflect, at least to some extent, a specific involvement at the level of central nervous system in some COVID-19 patients.
"It is particularly interesting that COVID-19 seems to particularly affect sweet and bitter taste receptors, because these are known to play an important role in innate immunity.
"More research is needed to see whether genetic variation in people's bitter and sweet taste receptors might predispose them to COVID-19, or conversely, whether COVID-19 infection changes how these receptors function, either directly or through a cytokine storm—the over-reaction of the body's immune system."
More information: 'Comparison of COVID-19 and Common Cold Chemosensory Dysfunction' is published in the journal Rhinology on August 19, 2020.
Uharibifu wa harufu ya COVID-19 ni tofauti na homa ya kawaida Utafiti mpya kutoka kwa kikundi cha wataalamu wa shida ya harufu, pamoja na Profesa Philpott kutoka Chuo Kikuu cha East Anglia, unaonyesha jinsi upotezaji wa harufu unaohusiana na maambukizo ya COVID-19 unavyotofautiana na kile unachoweza kupata na homa mbaya au homa. Utafiti huo wa kwanza unaonyesha jinsi watu walio na COVID-19 wanaovutiwa na harufu na ladha tofauti na wale walio na sababu nyingine za maambukizi ya njia za kupumua za juu. "Matofali hayo yanaonyesha kuwa wagonjwa wa COVID-19 wanapoteza hisia zao za kunusa, wanaweza kupumua kwa uhuru, hawana pua ya mkojo au kufungwa, na hawawezi kugundua ladha kali au tamu.""" Matokeo hayo yanaunga mkono nadharia ya kwamba COVID-19 huambukiza ubongo na mfumo wa neva wa kati. Timu ya utafiti inatarajia kwamba kazi yao inaweza kusaidia kuendeleza harufu na ladha vipimo kwa ajili ya haraka COVID-19 uchunguzi katika huduma ya msingi na idara za dharura. "Mtaalamu mkuu wa utafiti, Profesa Carl Philpott, kutoka Chuo Kikuu cha Matibabu cha Norwich, alisema: ""Kupoteza hisia za kunusa na ladha ni dalili ya kawaida ya COVID-19, lakini pia ni dalili ya kawaida ya kuwa na homa mbaya." """Tulitaka kujua ni nini hasa kinachotofautisha kupoteza harufu ya COVID-19 na aina ya kupoteza harufu ambayo unaweza kuwa nayo na pua baridi na imefungwa." Timu ya utafiti ilifanya majaribio ya harufu na ladha kwa wagonjwa 10 wa COVID-19, watu 10 wenye homa mbaya na kikundi cha kudhibiti cha watu 10 wenye afya, wote waliofanana kwa umri na jinsia. "Prof Philpott alisema: ""Tulitaka kuona ikiwa alama zao za majaribio ya harufu na ladha zinaweza kusaidia kutofautisha kati ya wagonjwa wa COVID-19 na wale walio na homa nzito." "Tunajua kwamba COVID-19 hujiendesha tofauti na virusi vingine vya kupumua, kwa mfano kwa kusababisha mfumo wa kinga wa mwili kuitikia kupita kiasi, inayojulikana kama dhoruba ya cytokine, na kwa kuathiri mfumo wa neva. """ "Kwa hiyo tulidhani kwamba mifumo ya kupoteza hisi ya harufu ingetofautiana kati ya vikundi hivyo viwili. "Tunaona kwamba kupoteza hisia za harufu ni jambo la kawaida katika watu walioambukizwa virusi vya COVID-19.""" Walikuwa na uwezo mdogo wa kutambua harufu, na hawakuweza kutambua ladha kali au tamu. Kwa kweli, ilikuwa ni hasara hii ya ladha ya kweli ambayo ilionekana kuwapo kwa wagonjwa wa COVID-19 ikilinganishwa na wale walio na homa. "Hii ni ya kusisimua sana kwa sababu inamaanisha kwamba majaribio ya harufu na ladha yanaweza kutumika kutofautisha kati ya wagonjwa wa COVID-19 na watu wenye homa ya kawaida au homa. """ Ingawa vipimo hivyo haviwezi kuchukua nafasi ya vifaa rasmi vya utambuzi kama vile swabs ya koo, vinaweza kutoa mbadala wakati vipimo vya kawaida havipatikani au wakati uchunguzi wa haraka unahitajika - haswa katika kiwango cha huduma ya msingi, katika idara za dharura au kwenye viwanja vya ndege. Utafiti huu pia unaonyesha kuwa kuna mambo tofauti kabisa yanayotokea linapokuja suala la kupoteza harufu na ladha kwa wagonjwa wa COVID-19, ikilinganishwa na wale walio na homa mbaya. "Hata hivyo, kuna uwezekano kwamba virusi vya COVID-19 huathiri mfumo wa neva wa kati, kulingana na dalili za neva zilizobuniwa na wagonjwa wengine.""" Pia kuna kufanana na SARS, ambayo pia imeripotiwa kuingia kwenye ubongo, labda kupitia vipokezi vya harufu katika pua. "Matokeo yetu yanaonyesha, angalau kwa kiwango fulani, ushiriki maalum katika kiwango cha mfumo wa neva wa kati katika baadhi ya wagonjwa wa COVID-19.""" "Ilikuwa na maana kubwa kwa wataalamu kwamba COVID-19 inaonekana kuathiri hasa mapokezi ya ladha tamu na uchungu, kwa sababu hizi zinajulikana kucheza jukumu muhimu katika kinga ya asili. """ "Utafiti zaidi unahitajika kuona ikiwa tofauti ya maumbile katika vipokezi vya ladha ya uchungu na tamu ya watu inaweza kuwafanya wawe na COVID-19 au kinyume chake, ikiwa maambukizo ya COVID-19 hubadilisha jinsi vipokezi hivi vinavyofanya kazi, moja kwa moja au kupitia dhoruba ya cytokine - athari ya juu ya mfumo wa kinga wa mwili. """ "Kuchunguza kwa kina ""Ulinganisho wa COVID-19 na Kizunguzungu cha kawaida cha Chemosensory Dysfunction"" ni utafiti wa utafiti wa kawaida wa ugonjwa wa baridi kali na ugonjwa wa baridi kali, uliochapishwa katika jarida la Rhinology mnamo Agosti 19, 2020."