A 6-year-old child in rural India presents with fever, headache, and altered mental status. CSF shows lymphocytic pleocytosis with normal glucose and mildly elevated protein. Viral culture and PCR are pending. What is the most common viral cause of meningitis in children in India?

Explanation

## Most Common Viral Cause of Meningitis in Children **Key Point:** Enteroviruses (Coxsackievirus and Echovirus) are the most common cause of viral meningitis worldwide and in India, accounting for 50–80% of cases with identified viral etiology. ### CSF Profile in Viral Meningitis | Feature | Enteroviral Meningitis | |---------|------------------------| | Cell count | 10–1,000/μL (typically 50–500) | | Cell type | Lymphocyte predominance (>50%) | | Protein | Mildly elevated (50–100 mg/dL) | | Glucose | **Normal** (>40 mg/dL, CSF:serum ratio >0.4) | | Gram stain | Negative (no organisms) | | Culture | Positive in 40–70% of cases (enterovirus culture/PCR) | | RT-PCR | Most sensitive and specific diagnostic test | ### Comparison: Viral vs. Bacterial Meningitis CSF | Parameter | Bacterial | Viral (Enterovirus) | |-----------|-----------|--------------------| | WBC count | 100–10,000 | 10–1,000 | | Cell type | Neutrophils (early) | Lymphocytes | | Glucose | **Low (<40 mg/dL)** | **Normal** | | Protein | Very high (100–500) | Mildly elevated (50–100) | | Gram stain | Often positive | Negative | **High-Yield:** The **normal glucose level** in viral meningitis is the key discriminator from bacterial meningitis. Enteroviruses do not consume glucose or impair its transport into CSF. ### Enterovirus Epidemiology in India - **Seasonal:** Peak in summer and monsoon (warm, humid climate favors transmission) - **Transmission:** Fecal-oral route; highly contagious in daycare and school settings - **Age:** Most common in children <5 years; can occur at any age - **Prevalence:** Responsible for >50% of aseptic meningitis cases in India - **Prognosis:** Generally self-limited; mortality <1% in immunocompetent children **Clinical Pearl:** Enteroviral meningitis often presents with a biphasic illness — initial febrile illness followed by meningeal symptoms — and may be accompanied by rash, myalgia, or hand-foot-mouth disease. ### Why Other Viruses Are Less Common **Mnemonic: JEMM** — *Japanese encephalitis, Enteroviruses (most common), Measles, Mumps* 1. **Measles virus:** Rare in vaccinated populations; now <1% of viral meningitis in India (MMR vaccine coverage improving) 2. **Mumps virus:** Rare in vaccinated populations; <1% of cases in countries with MMR vaccination 3. **Japanese encephalitis virus:** Causes encephalitis (not pure meningitis) with altered consciousness, seizures, and focal neurological signs; endemic in certain regions (Uttar Pradesh, Bihar) but less common than enterovirus **Warning:** Do not confuse viral meningitis (normal glucose, lymphocytes, self-limited) with bacterial meningitis (low glucose, neutrophils, life-threatening). Japanese encephalitis presents with encephalitis (altered mental status, seizures, focal deficits), not isolated meningitis.