A 5-year-old child has temperature rise up to 39, 2°C, sore throat, nausea. Objectively: mucous membrane of soft palate and palatine arches is brightly hyperemic, it can be distinctly distinguished among the surrounding tissues. The tongue is dry, edematic, bright-red, its lateral surfaces have no fur on them, fungiform papillae are evidently enlarged. Face skin is hyperemic apart of pale nasolabial trigone, is covered with spotty rash. Submaxillary lymph nodes are palpatory painful. What is the causative agent of this disease?