Question

The most common cause of meningoencephalitis in children is?

• A. Herpes simplex virus (HSV)
• B. Enterovirus
• C. Mumps
• D. Listeria

Hint:

Commonest equals enterovirus; HSV is commonest only for severe sporadic encephalitis.

Answer 1

The Correct Option is B

Sort these options by frequency rather than by severity, because the question asks for the commonest cause, not the most dangerous one. The great majority of childhood meningoencephalitis is viral and self-limited, so the answer should be the virus that circulates most widely in children. Enteroviruses, the coxsackie and echo group, spread readily by the fecal-oral route, peak in the warmer months, and account for the largest share of aseptic meningitis and meningoencephalitis in pediatric practice, which makes them the statistical front-runner. It is tempting to pick herpes simplex virus, but HSV earns its fame as the leading cause of severe, sporadic, potentially fatal encephalitis that mandates prompt acyclovir, not as the most frequent cause; high lethality is not the same as high incidence. Mumps was once a notable contributor but has receded sharply where MMR vaccination is in place, so it no longer leads. Listeria is a bacterium whose central nervous system disease concentrates in neonates and immunocompromised or elderly hosts, which excludes it as the typical childhood answer. Ranking purely on how often each agent causes disease in children leaves enterovirus on top. $\text{Most frequent} \neq \text{most lethal}; \text{enterovirus} = \text{most frequent}$.\[\boxed{\text{Enterovirus}}\]