Pathognomic of measls -

Ans. is 'a' i.e., Koplik spot Measleo Caused by RN A virus.o Highly contagious droplet spread from secretion of nose and throat 4 day before and 5 days after rash,o Secondary attack rate >90% in contact.o Prodromal phase - characterized by fever, rhinorrhea, conjuctival congestion and dry hackig cough,o Koplik spots bluish-gray specks or ''grains of sand" on a red base-develop on the buccal mucosa opposite the second molarsGenerally appear 1 -2 days before the rash and fast 3-5 daysPathognomonic for measles, but not always presento Rash appears on D4 first behind pinna on neck the spread of face, thrunk and abdomen,o SSPE is long term complication seen in measls.