This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Not true about varicella infection - 
Select and explain. 
A. Secondary attack rate is 90%, B. Lesions occur on flexor surfaces, C. Only single stage of lesion is present at a time, D. Reactivation occur in 10-30% cases
C: Only single stage of lesion is present at a time
Answer: C: Only single stage of lesion is present at a time 
Explanation: The characteristic feature of chicken pox is "Pleomorphism", that is, all stages of the rash (papules, vesicles, and crusts) may be seen simultaneously at one time in the same area.

Chickenpox (varicella infection) is highly communicable by droplet infection with a secondary attack rate of approximately 90%.
Rashes of chicken pox are symmetrical and occur mostly on flexor surface.
Latent infection is established in the cranial nerve, sensory ganglia, and spinal dorsal root ganglia. The virus may reactivate in immuno-suppressive conditions, resulting in herpes zoster in about 10-30% of persons.