Which viruses are responsible for >90% of aseptic meningitis cases?

• A. Enteroviruses (coxsackie, echo, polioviruses)
• B. Herpesviruses
• C. Varicella zoster virus
• D. Influenza viruses

Answer: (A)

Enteroviruses are the most common cause of aseptic meningitis, responsible for more than 90% of cases. These viruses, including coxsackie and echoviruses, are transmitted fecal-oral and often infect children or young adults. They invade the meninges, causing classic meningitis symptoms with viral CSF findings: lymphocytic predominance, normal glucose, and only modest protein elevation, while Gram stain and bacterial cultures are negative. Diagnosis is often confirmed with PCR testing for enteroviruses on CSF. The illness is typically self-limited and treated supportively; antibiotics are not needed once bacterial meningitis is excluded. Other viruses—such as herpesviruses, varicella-zoster virus, and influenza—can cause meningitis but do so much less frequently and usually in specific clinical contexts (e.g., immunocompromise, neonates, or disseminated disease), which is why they do not account for the bulk of aseptic meningitis cases.