Out for blood

Tick on a paper towel as seen under a magnifying loupe. 

Those pink splotches of calamine lotion adorning arms and legs are summer’s badge of honor — showing you’ve been outside and faced down the hordes of midges, mosquitoes and ticks out for your blood.

It’s bad enough that these insects want your blood, but why the maddening itch?

Emily McDermott, assistant professor of entomology for the University of Arkansas System Division of Agriculture, said it has to do with the human immune system.

“The itchiness is an allergic reaction to insect saliva,” she said. “As an insect or tick is biting, it’s salivating into the wound. It needs to introduce compounds that will keep the blood flowing.”

While the insect tries to draw the blood out, the human body is working to keep it inside.

“The insect’s saliva is combatting platelet aggregation, vessel restriction and clotting,” McDermott said. “That’s what your body is reacting to — trying to defend against foreign compounds.”

Itch versus scratch

The immune response creates the itch, but does it have any advantage for the one being bitten?

“Itching is kind of a way to protect your body from things. That immediate itch is a ‘get-that-off-me’ response,” McDermott said.

However, that’s not foolproof. In some cases, the body’s itch reaction to a bite may take days or weeks, long after the insect is gone, she said.

However, outside of the initial “shoo” potential, scratching isn’t all that healthy.

“The pain of scratching overrides the itchy sensation,” McDermott said. “It causes the brain to release serotonin, which make the itch more intensive.

“The more you scratch, the more you itch,” she said, which increases the likelihood of tearing the skin.

Over-the-counter remedies like calamine lotion or cortisone-based creams can help dull the itch. McDermott uses an ice cube, with the cold producing “reduced nerve response.”

(0) comments

Welcome to the discussion.

Keep it Clean. Please avoid obscene, vulgar, lewd, racist or sexually-oriented language.
Don't Threaten. Threats of harming another person will not be tolerated.
Be Truthful. Don't knowingly lie about anyone or anything.
Be Nice. No racism, sexism or any sort of -ism that is degrading to another person.
Be Proactive. Use the 'Report' link on each comment to let us know of abusive posts.
Share with Us. We'd love to hear eyewitness accounts, the history behind an article.