Olfactory dysfunction from acute upper respiratory infections: relationship to season of onset

Abstract

Background: Acute viral upper respiratory tract infections are the most common cause of chronic olfactory dysfunction. In light of the seasonality of numerous viruses, the question arises as to whether the frequency and magnitude of postviral olfactory disorders (PVODs) are similarly seasonal. We sought to determine whether olfactory deficits due to influenza and non-influenza-related viruses (I-PVODs and NI-PVODs) vary in frequency or magnitude across seasons in a North American population and whether they are more prevalent or produce more severe olfactory dysfunction during colder months when host susceptibility may be increased. Methods:This was a retrospective study of 587 patients presenting to an academic smell and taste center with either I-PVOD-related or NI-PVOD-related olfactory deficits. Chi-square and analysis of covariance (age = covariate) compared dysfunction prevalence frequencies and scores on the University of Pennsylvania Smell Identification Test (UPSIT) across calendar months and between months with the coldest and warmest air temperatures. Results:For I-PVOD-related cases, both the prevalence and magnitude of smell dysfunction were highest in the colder months. However, for NI-PVOD-related cases, prevalence was higher in warmer months but, paradoxically, the magnitude of dysfunction was higher in colder months. Conclusion:This study shows that seasonal variations occur in both the prevalence and magnitude of PVOD-related olfactory deficits in a North American population, and that such variations differ between NI-PVOD and I-PVOD cases. The findings suggest multiple viruses are involved in producing PVOD-related olfactory deficits. C 2020 ARS-AAOA, LLC. How to Cite this Article:Po er MR, Chen JH, Lobban N-S, Doty RL. Olfactory dysfunction from acute upper respiratory infections: relationship to season of onset. Int Forum Allergy Rhinol. 2020;10:706-712.

Prevalence and reversibility of smell dysfunction measured psychophysically in a cohort of COVID‐19 patients

“…There is evidence that smell loss continues to be present in COVID‐19 patients after rRT‐PCR test findings have returned to normal 13 . Most likely, acute virus‐related damage to the olfactory epithelium is the basis for the smell deficit of COVID‐19, as seen in other viral infections 33,34 . The degree of return of function likely reflects the propensity of the olfactory neuroepithelium to regenerate and the amount of previous epithelial damage from cumulative xenobiotic insults 35,36 .…”

COVID‐19 Viral Load in the Severity of and Recovery From Olfactory and Gustatory Dysfunction

“…24 Anosmia has been well documented in coronavirus infections. 25,26 However, the exact pathophysiological mechanism by which COVID-19 causes olfactory and gustatory dysfunction is still unknown. 27 Postviral olfactory disturbance can be caused by nasal obstruction blocking odors from reaching the olfactory cleft, a conductive impairment, or damage to the olfactory nerve, which is a sensorineural impairment.…”

Smell and taste changes are early indicators of the COVID-19 pandemic and political decision effectiveness

“…To the best of our knowledge, there are no existing studies that have explored the dynamics of sudden anosmia (as in COVID-19) throughout the year in France. Relationship between olfactory disturbances and seasons have been reported in Korea, Germany or US with a moderate increase of anosmia prevalence in spring [17][18][19] . Although the cyclical pattern of smell/taste changes might overlap, the amplitude of reported changes (either due to allergy or viral affection) were very limited compared to the present report.…”