This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory Infections, Subject name: Social & Preventive Medicine
[{'content': 'A 2 year old unimmunized child present to a primary health center with fever since 5 days. Mother also give a history of rash staing behind ear- pinna a day before coming to OPD. On examination, child is having running nose and congested eyes. Most probable diagnosis is:- \nSelect and explain. \nA. Measles, B. Mumps, C. Rubella, D. Chicken pox', 'role': 'user'}, {'content': 'Answer: A \nExplanation: MEASLES:- Incubation period: 10 - 14 days Causative agents: RNA paramyxovirus Sources of infection: cases (carriers are not known to occur) Period of communicability :4 days before & 5 days after the appearance of rash (Rash: Retro - auricular origin) Measles has no second attacks (life long immunity seen) Pathognomic clinical feature of measles: Koplik spots (on buccal mucosa opposite lower 2nd molar) Other clinical features: Coryza, fever, Red eye, Cough MC complication of measles in young children: Otitis media.', 'role': 'assistant'}]