This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology Pa-2 (RNA Virus Pa-1,2 & Miscellaneous Viruses), Subject name: Microbiology
[{'content': 'The most likely cause of bronchiolitis in a 6 months old infant is: \nSelect and explain. \nA. Measles virus, B. Mumps virus, C. Respiratory syncytial virus, D. Parainfluenza virus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Option 3 RESPIRATORY SYNCYTIAL VIRUS Infants: RSV is the most common cause of lower respiratory tract infection below 1 year of age, causing bronchiolitis, pneumonia, and tracheobronchitis. Bronchiolitis is usually self-limiting, but may cause a serious disease in premature infants, in immunocompromised hosts, and in individuals with underlying lung diseases. Option 1, 2 Measles virus and Mumps virus do not cause bronchiolitis. Option 4 Human parainfluenza viruses are one of the major causes of lower respiratory tract disease: Common cold syndrome such as rhinitis and pharyngitis is the MC presentation Croup (laryngotracheobronchitis): Seen with type 1 and 2 and involves older children Pneumonia or bronchiolitis: Seen with type 3, but less common than RSV.', 'role': 'assistant'}]