Scarlet fever is an acute illness which is caused by a systemic infection with the bacterium Streptococcus pyogenes. It is characterized by a reddish skin rash, sore throat, fever, and vomiting; it may also be accompanied by tonsilitis and a reddening of the tongue (called "strawberry tongue").
From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.