Meningitis

This section will focus on viral meningitis, specifically caused by Herpes Simplex Virus (HSV) and Enteroviruses, covering their etiology, epidemiology, transmission, and disease states

Viral Meningitis

• Definition: Meningitis is inflammation of the meninges, the membranes that surround the brain and spinal cord. Viral meningitis is typically less severe than bacterial meningitis
• Etiology: Various viruses can cause meningitis, but the most common are enteroviruses, herpes simplex virus (HSV), varicella-zoster virus (VZV), mumps virus, and West Nile virus

Enteroviruses

• Etiology
  • Classification: A member of the Picornaviridae family. Includes polioviruses, coxsackieviruses, echoviruses, and enteroviruses
  • Types: Numerous serotypes, with coxsackieviruses and echoviruses being the most common causes of viral meningitis
• Epidemiology
  • Seasonality: More common during the summer and fall months
  • Age Groups: Primarily affects children and young adults
  • Global Distribution: Found worldwide
• Transmission
  • Fecal-Oral Route: Primarily spread through the fecal-oral route, meaning through contact with fecal matter and then ingestion
  • Respiratory Droplets: Can also be spread through respiratory droplets
• Disease States
  • Viral Meningitis: Characterized by fever, headache, stiff neck, sensitivity to light (photophobia), and nausea/vomiting
  • Other Infections: Enteroviruses can also cause a variety of other illnesses, including hand, foot, and mouth disease, herpangina, conjunctivitis, and myocarditis
  • Severity: Usually self-limiting and resolves within 1-2 weeks

Herpes Simplex Virus (HSV)

• Etiology
  • Classification: A member of the Herpesviridae family
  • Types: HSV-1 and HSV-2 can both cause meningitis, although HSV-2 is more commonly associated with recurrent meningitis (Mollaret’s meningitis)
• Epidemiology
  • Prevalence: HSV infections are very common, but meningitis is a less frequent complication
  • Age Groups: Can affect individuals of any age
• Transmission
  • Direct Contact: Spread through direct contact with lesions or asymptomatic shedding
  • Sexual Contact: HSV-2 is primarily transmitted through sexual contact
• Disease States
  • Viral Meningitis: Similar symptoms to enteroviral meningitis but can be more severe
  • Encephalitis: HSV-1 is a common cause of encephalitis (inflammation of the brain), which can be life-threatening
  • Neonatal Herpes: Can cause meningitis in newborns
  • Mollaret’s Meningitis: Recurrent episodes of meningitis associated with HSV-2
  • Severity: HSV meningitis can be more severe than enteroviral meningitis, especially if encephalitis is present

Diagnosis of Viral Meningitis

• Lumbar Puncture (Spinal Tap): Essential for diagnosing meningitis. Cerebrospinal fluid (CSF) is collected and analyzed
• CSF Analysis
  • Cell Count: Elevated white blood cell count (pleocytosis), primarily lymphocytes
  • Protein: Normal or slightly elevated protein levels
  • Glucose: Normal glucose levels (helps differentiate from bacterial meningitis, where glucose is typically low)
  • Gram Stain and Culture: Negative for bacteria (rules out bacterial meningitis)
• Viral Testing
  • PCR: Polymerase chain reaction (PCR) is the most sensitive and specific method for detecting viral DNA or RNA in CSF. Used to identify enteroviruses, HSV, VZV, and other viruses
  • Viral Culture: Less commonly used due to lower sensitivity and longer turnaround time compared to PCR
• Other Tests: Blood tests and imaging studies (e.g., MRI) may be performed to rule out other causes of meningitis or encephalitis

Treatment of Viral Meningitis

• Supportive Care: Rest, fluids, and pain relief are the mainstays of treatment
• Antiviral Medications: Acyclovir is used to treat HSV and VZV meningitis or encephalitis
• Hospitalization: May be necessary for severe cases or if encephalitis is suspected

Prevention of Viral Meningitis

• Good Hygiene: Frequent handwashing can help prevent the spread of enteroviruses
• Vaccination: Vaccines are available for mumps, measles, rubella, and varicella, which can prevent meningitis caused by these viruses
• Safe Sex Practices: Using condoms can reduce the risk of HSV-2 transmission
• Vector Control: Mosquito control measures can help prevent West Nile virus infection

Key Terms

• Etiology: The cause or origin of a disease or condition
• Epidemiology: The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems
• Transmission: The way a disease is spread from one person or source to another
• Meningitis: Inflammation of the meninges, the membranes that surround the brain and spinal cord
• Encephalitis: Inflammation of the brain
• Enteroviruses: A group of viruses that includes polioviruses, coxsackieviruses, and echoviruses
• Herpes Simplex Virus (HSV): A virus that can cause oral herpes, genital herpes, and meningitis
• Lumbar Puncture (Spinal Tap): A procedure to collect cerebrospinal fluid (CSF) for analysis
• Cerebrospinal Fluid (CSF): The fluid that surrounds the brain and spinal cord
• Pleocytosis: Elevated white blood cell count in the CSF
• PCR (Polymerase Chain Reaction): A molecular test used to detect viral DNA or RNA
• Acyclovir: An antiviral medication used to treat HSV and VZV infections
• Mollaret’s Meningitis: Recurrent episodes of meningitis associated with HSV-2
• Fecal-Oral Route: Transmission of pathogens through contact with fecal matter and then ingestion
• Photophobia: Sensitivity to light