“Rob, I know you're a doctor—can I have a word about your son.” The reception class nursery nurse's words chilled me to the bone, as Jamie (aged 5) had been off colour for a few days. “I am a bit worried about the rash he has got on his face. Three other children in the class have a similar rash—do you think it is infectious?”

I looked at the bright red rash on his cheeks and, despite struggling for some time, no diagnosis came to mind and an embarrassing silence followed.

“Well …… I don't think it is infectious.”

“We need a doctor's letter to say that it is okay for Jamie to be at school.”

“I do infectious diseases—hang on I've got some headed paper in my bag, I'll write a note now.”

“No! We need a letter from a proper doctor—could you get a letter from his GP.”

A call on my mobile phone secured an urgent appointment with the GP. When we arrived the practice receptionist asked if we minded seeing the locum. Time was of the essence and I readily agreed. Walking into the locum's room I was greeted by the wife of our research registrar. After a full history (three days of malaise, feeling feverish and sweaty, a rash had appeared) and a thorough examination (there was nothing to find), she turned to me and said, “Well, I don't know what the rash is—do you?”

A letter for the school was quickly drafted, it read “I have seen Jamie Miller and I have also consulted an infectious disease consultant (surely not me?). We both agree Jamie is not infectious and may return to school.”

Armed with the letter I returned to school with Jamie. As I handed over the letter the nursery nurse seemed somewhat surprised—particularly as I learned that two more children in his class now had similar rashes. Jamie was delighted to be back among his friends.

That evening, Jamie was running around the house chasing his sister—dressed only in his socks and pants. The doorbell rang, a close friend (a dermatologist) had arrived for a coffee. Standing on the doorstep she eyed up Jamie. “He's got erythema infectiosum*—I'm not coming in—he's infectious!”

Now where are those revalidation documents from the GMC?