How is herpes meningitis acquired?

Acquisition of Herpes Meningitis

Herpes meningitis is primarily acquired through sexual contact with a person infected with herpes simplex virus (HSV), particularly HSV-2, which can be transmitted even when the infected partner has no visible genital lesions or is asymptomatic at the time of sexual contact. 1

Transmission Routes

• HSV-2, which causes most cases of herpes meningitis, is predominantly transmitted through sexual contact with infected genital secretions, even when the infected person has no visible lesions 1
• Many cases of genital herpes (and subsequent meningitis) are acquired from persons who do not know they have genital HSV infection or who were asymptomatic during sexual contact 1
• HSV-1, traditionally associated with oral infections, can also cause genital herpes and subsequent meningitis through oro-genital sexual practices 1
• Viral reactivation from latent infection in sacral ganglia can lead to recurrent episodes of herpes meningitis without new exposure 1

Risk Factors and Special Scenarios

• Immunocompromised status significantly increases the risk of developing severe meningitis from HSV-2 infection 2
• History of recurrent genital herpes increases risk, though many patients with herpes meningitis (>90%) have no known history of genital herpes 3, 4
• Women appear more susceptible, with studies showing approximately 74-83% of herpes meningitis cases occurring in females 3, 4
• Rare non-sexual transmission routes have been documented, including:
  • Following lumbar steroid injections in patients with latent HSV infection 3
  • Peripartum period (particularly following cesarean section) 3

Clinical Presentation

• Most patients with herpes meningitis present without concurrent genital lesions or history of genital herpes 3, 4, 5
• Symptoms typically include headache (100%), photophobia (47%), self-reported fever (45%), meningismus (44%), and nausea/vomiting (29%) 4
• Recurrent episodes of aseptic meningitis (Mollaret's meningitis) can occur due to HSV-2 reactivation 4, 6
• CSF analysis typically shows lymphocytic pleocytosis, elevated protein, and normal glucose levels 4, 6

Diagnostic Considerations

• PCR testing of CSF for HSV DNA is the gold standard for diagnosis of herpes meningitis 1, 5
• Genital examinations are often not performed in patients with meningitis symptoms, potentially missing the connection to HSV 3
• Type-specific testing (differentiating HSV-1 from HSV-2) is important for proper patient counseling and management 1

Prevention

• Consistent and correct condom use may reduce but not eliminate transmission risk
• Suppressive antiviral therapy in persons with known genital herpes reduces viral shedding and may reduce transmission risk 1
• Avoiding sexual contact during active outbreaks of genital herpes 1

Clinical Pitfalls to Avoid

• Failing to consider HSV as a cause of aseptic meningitis, especially in recurrent cases
• Not performing PCR testing for HSV in CSF of patients with aseptic meningitis
• Assuming that absence of genital lesions rules out herpes meningitis 3, 5
• Delaying antiviral treatment in immunocompromised patients, which can lead to worse outcomes including encephalitis and death 2