This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Cyclic trends are seen in which of the following 
Select and explain. 
A. Rabies, B. Measles, C. Cholera, D. Hepatitis
B: Measles
Answer: B: Measles 
Explanation: .some disease occur in cycles spread over sho periods of time which may be days ,weeks,or months.or years.for example measles in pre vaccination era appeared in cycles with major peaks every 2 to 3 years and rubella every 6 or 9 years.this was due to naturally occurring variations in herd immunity. ref:park&;s textbook,ed 22,pg no 62