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: Pediatrics
A patient had fever and coryza for last 3 days developed maculopapular erythematous rash with which lasted for 48 hrs and disappeared without leaving behind pigmentation is most commonly due to- 
Select and explain. 
A. Measles, B. Typhoid, C. Roseola infantum, D. Fifth disease
C: Roseola infantum
Answer: C: Roseola infantum 
Explanation: Ans. is 'c' i.e., Roseola infantum o The child is having roseola infantum. It is caused by Human herpes - 6 (HHV-6). The most prominent feature is abrupt onset of fever often reaching 40.6degC. The fever then ceases abruptly and a characteristic rash may appear. The rashes are maculopapular. Are non pruritic tend to coalesce and disappears in 1-2 days without pigmentation or desquamation. o Erythema infectiosum or fifth disease can be easily ruled out because the first sign of illness is the rash no fever. The rashes are masculopapular and they coalesce to given a slapped check appearance. One half of the infected children have some rash remaining for 10 days fine desquamation may be present. o In measles the rashes last for 6-7 days. o In typhoid the rashes appear on the 7th day of illness.