Scarlet Fever on today's Moment of Science.
Contrary to popular belief, scarlet fever is no longer the deadly disease it was in the 1800's. It can lead to serious problems like acute rheumatic fever and toxic shock syndrome, but those cases are rare. It infects adults and children alike. However, scarlet fever mostly infects children because by the time they are ten years old, 80% of children have developed lifelong antibodies that protect them from future infection with the bacteria. But that leaves 20% of us unprotected.
Scarlet fever is basically strep throat, but with a rash. Toxins produced by the nasty streptococci bacteria are released at the site of infection and are absorbed into the infected person's blood stream. These toxins circulate throughout the body, potentially causing injury in places distant from the infection. These same toxins irritate the skin and cause it to turn a deep red, something like a sunburn. It often itches. As the rash fades away around the sixth day of the infection, some of the skin may peel. To make matters worse, though, scarlet fever, as I've said, is more than a rash. It's strep throat. The throat begins to throb and is probably coated with pus. The infection often begins with a fever over 101 degrees Fahrenheit.