It seems hard to believe that a basic human sensation — one that can be evoked by a simple mosquito bite — still has scientists scratching their heads. Yet despite centuries of study, understanding itching is still fraught.
Itch, write two scientists in a review in the journal Immunity, “has been described as one of the most diabolical sensations. In Dante's Inferno, falsifiers were eternally punished by ‘the burning rage of fierce itching that nothing could relieve.’” Yet, the researchers note, “There have been very few advances in itch treatment in over 360 years.”
That’s finally starting to change. In the past decade, scientists have made strides toward understanding this infuriating sensation. They are untangling itchiness from other noxious stimuli, such as pain. They are even starting to distinguish one type of itch from another, by poking study participants with itch-inducing plant spikes or deleting itch-related genes from mice.
This wide-ranging research is gradually going beyond an understanding of familiar acute histamine-driven itch — the mosquito or poison ivy variety — to reveal the complicated mechanisms and players involved in the often debilitating type of itching that lasts for weeks and sometimes years. Chronic itch, as it’s termed, can be generated by a multitude of factors, from chemicals secreted within the body to nerves gone haywire, and in many cases, has no known cause or cure.
his inquiry is more than an academic exercise (or a quest to make mosquito welts recede faster). While acute itch is fleeting, chronic itch may plague some 7 percent of people each year, and one in five people will experience it at some time in their lives. Beyond a maddening persistent urge to scratch, the condition can lead to depression, sleep deprivation and a drastic decrease in the quality of life. “It can be as devastating as chronic pain,” says Robert LaMotte, an itch researcher at the Yale School of Medicine.
