This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Communicable Diseases, Subject name: Social & Preventive Medicine
Sub acute - Sclerosing pan - encephalitis (SSPE) is caused by 
Select and explain. 
A. Measles, B. Mumps, C. Rubella, D. Small pox
A: Measles
Answer: A: Measles 
Explanation: (Measles) (137-Park 20th)* Subacute sclerosing pan-encephalitis (SSPE) is a rare complication which develops many years after the initial measles infections. It is characterized by progessive mental deterioration leading to paralysis, probably due to persistence of the virus in the brain.* Measles vaccination definitely constitutes a protection against the neurological and other complications by preventing natural measles from occurring* **A11 cases of severe measles and all cases of measles in areas with high case fatality rates should be treated with vitamin A