"Not only is the Muggle world free of such perils as Devil's Snare and Blast-Ended Skrewts, the Statute of Secrecy has also kept us free from contact with anyone who could pass on Dragon Pox (as the name implies, originally contracted by wizards working closely with Peruvian Vipertooths)."
-- Pottermore "Illness and Disability" (Pm)
Cure for the alarming, disfiguring, contagious and sometimes fatal wizarding disease
The talented and much-loved healer Gunhilda of Gorsemoor developed a cure for Dragon Pox in the 16th century (fw/37).
Professor Helbert Spleen, however, replies to Howland Coopey in the Daily Prophet that Dragon Pox will go away of its own accord. This advice seems to be an error and hopefully Mr Coopey will take himself into the hospital as soon as possible for the proper cure (DP3)
Dragon Pox is treated on the second floor of St. Mungo's (OP22)
While the date printed on DP3 is 1 June 1999, the timeframe for these events is 1992-1993.