What’s in an itch?
Walking out of a patient’s room, I develop an itch. An itch around my neck, on my forehead, and in the middle of my back. I cannot help but scratch and feel some relief.
My patient, a thin woman in her 50s, who works in a day care center, has a rash, red papules on her legs and arms. Her papules have finger-length streaking scratch marks. The rash is somewhat scabbed with coalesced papules, and the leg has become red and warm, a sign of cellulitis, a skin infection.
Over the next few days, I treat her with antibiotics for the bacterial skin infection. Although the skin is less red and warm, the itching does not go away. But neither does my itch each time I exit her room, even when I have not touched her rash. That’s when I suspected that there is something more to her illness than just a bacterial infection.
Itching is a strange sensation, different from pain or a tickle. We all experience it, often times children more than adults, and at any given time nearly 15 percent of us suffer from a chronic itch.
Yet, when a patient comes to me with the complaint of itching, the diagnosis can be puzzling. Anything from an infection to liver failure, to lymphoma to stress and anxiety or dry skin can cause chronic itching.
Evolutionarily speaking, itching has a purpose. Just as pain warms us of injurious stimuli, such as a hot pan, or a car door mashing our finger, itching warns us of possible noxious agents such as a malaria- or West Nile-infected mosquitoes or poison ivy plant.
Though we cannot relieve pain, we can relieve an itch, simply by scratching. In fact, scratching relieves the itch by stimulating pain receptors and inhibiting local nerve circuits in the spinal cord and the brain. Some studies show that the relief of an itch is as a pleasing a sensation as sex.
But what is most insidious about an itch is that it is contagious; the mere mention of an itch fires the itch neuron. Even reading about itching causing one to itch, just like watching someone yawn triggers a yawn. A good number of readers will find themselves itching as they continue to read this piece.
So what was happening with my patient? I learned the itch was chronic, having gone on for months. She had no other medical illness, and she wasn’t on any new medication. That pointed to a possible contact agent or an infectious one. That’s when I suggested that scabies may be the culprit.
Appalled at my suggestion, she said, “ How did I get scabies? I keep good hygiene.” In fact, scabies, a mite, affects people of all ages and races and socioeconomic conditions, in places around the world. Scabies is especially common in children, though, so perhaps her work in a day care center exposed her to the parasite.
Scabies burrows in at wrists and ankles, lays its eggs in the top layer of the skin. Its lesions are found in skinfolds of the finger webs or groin. While it’s hard to definitively diagnosis scabies, its treatment is simple — a medicated shampoo from head to toe. In a few days the itching was gone.
So why was I itching? While scabies is contagious, my itching was likely all in my head. Remarkably, my own itching stopped, along with my patient’s.
Source : Commercial Appeal