Incubation Period for Herpes Meningitis
The incubation period for herpes meningitis is typically two to ten days, but can extend up to four weeks. 1
Clinical Overview
- Herpes simplex virus (HSV) is a common cause of viral meningitis, with HSV-2 being the most frequently recognized infectious cause of benign, recurrent meningitis 2
- Herpes meningitis can occur during primary infection or as a reactivation of latent infection, with symptoms typically developing within the incubation period of the virus 1
- The incubation period applies to both HSV-1 and HSV-2 infections that may lead to meningitis 1
Clinical Presentation
- Common symptoms of herpes meningitis include headache (100%), photophobia (47%), self-reported fever (45%), meningismus (44%), and nausea/vomiting (29%) 2
- CSF analysis typically shows elevated protein (mean 156 g/dL) and white cell count (mean 504 cells/μL) with normal glucose levels 2
- Lymphocytic pleocytosis is characteristic of herpes meningitis, with a mononuclear predominance of approximately 97% 3
Risk Factors and Demographics
- HSV-2 meningitis affects women more frequently than men (76% of cases are female) 3
- The median age of presentation is approximately 35 years 3
- Importantly, most patients with HSV-2 meningitis do not report a history of genital herpes (only 23% report prior genital herpes) 2
- Immunocompromised patients may develop more severe forms of herpes meningitis with potential progression to encephalitis 4
Diagnostic Considerations
- Diagnosis is confirmed by detection of HSV DNA in cerebrospinal fluid via PCR 2
- The median time from symptom onset to HSV-2 detection in CSF is approximately 3 days 2
- Neuroimaging is typically normal (83%) in cases of herpes meningitis without encephalitis 2
- It's critical to distinguish between meningitis and encephalitis, as encephalitis represents a more severe condition requiring more aggressive treatment 5
Treatment Approach
- For confirmed HSV meningitis, intravenous acyclovir is the treatment of choice 1
- Treatment duration varies, but typically ranges from 3-14 days for uncomplicated meningitis 6
- More severe cases or those with encephalitis components require longer treatment courses (14-21 days) 5
- Treatment should be initiated as soon as possible after symptom onset for optimal outcomes 5
Prognosis and Follow-up
- Most patients with herpes meningitis have good outcomes without long-term neurological disability 2
- However, unfavorable outcomes at discharge are common (31% of patients), with 11% still having sequelae after 6 months 3
- Recurrence is not universal but can occur in some patients, particularly with HSV-2 2
Important Caveats
- Herpes meningitis can occur without concurrent genital lesions or symptoms 2
- Delayed initiation of antiviral therapy is associated with worse outcomes, particularly in immunocompromised patients 4
- The absence of a history of genital herpes does not rule out herpes meningitis 2
- Genital examinations are often not performed at presentation, potentially missing this diagnostic clue 6