COVID-19 brief note: the nose knows
Interestingly, smell sensation, technically olfaction, is a symptom preceding many Parkinson disease case cases. It is also a precursor to Alzheimer's disease.
The olfactory nerve, which transmits odor perception to the basal forebrain and brainstem is a part of the brain. The olfactory never is really a neural fiber tract, elongated and penetrating to the nasal mucosa. So far as I know the reason for loss of olfaction is as yet undiscovered.
So, fellow swampers and those remaining dry, here is a message: