The Christmas before last my son got a case of the flu he couldn’t shake. He had been running a fever for 8 days when he suddenly turned a bright pink all over as if he had just stepped out of a sauna. Then he developed itchy welts on his skin. Diphenhydramine (Benadryl) applied topically took the welts down so I knew the welts resulted from some kind of allergic reaction, but I couldn’t guess as to what, so off to the doctor’s we went.
The doctor looked at him and diagnosed strep throat. A $15 antibiotic and an over-the-counter cream for the itch and in a couple of days he was right as rain.
The pink skin and welts came from an interesting side effect of infection from the streptococcal bacteria that cause strep throat. The bacteria shed a protein called an endotoxin that has two effects on the body. First, it causes a dilation of the capillaries which causes a body wide blush. Second, the protein sticks to tissues in the body, especially the skin, which causes the body’s immune system to attack its own tissues. You might know of these effects under their historical name.
Scarlet fever.