measles, paralysis
痲 centers on a loss of normal bodily function: measles as a disease that causes skin eruptions and weakness, and paralysis as a loss of sensation or movement. Both meanings share the idea of a body overwhelmed by illness.
痲 combines 疒 (sickness) with 麻, which likely contributes the sound and may relate to the idea of numbness or skin eruptions. The exact historical development is uncertain.
The sickness enclosure 疒 wraps around 麻, a shape associated with hemp or numbness. Picture a body trapped by illness, skin breaking out in measles or limbs going numb like hemp fibers.
For マ, imagine a mother (ママ) caring for a child with measles: ママ -> マ, and her touch soothes the paralysis.