Herpes simplex encephalitis

Disease Description (Causes and Symptoms)

• Cause: Herpes simplex is an infection caused by the herpes simplex virus (HSV). HSV-1 mainly causes oral (lip) herpes, while HSV-2 mainly causes genital herpes. After infection, the virus remains latent in the ganglia (sensory ganglia) and may reactivate due to immunosuppression, fever, ultraviolet exposure, stress, and other factors.
• Summary of pathophysiology: Viral proliferation in the epidermis and mucous membranes → formation of grouped small vesicles → crusting after vesicle rupture → retrograde transport to nearby ganglia, where the virus remains latent. During recurrence, a localized reaction usually occurs, but in rare cases it may lead to central nervous system involvement (meningitis, encephalitis) or systemic dissemination.
• Main symptoms: Localized burning or tingling pain, itching, grouped vesicles (blisters), vesicle ulceration, and crust formation. Primary infection may be accompanied by systemic symptoms such as fever, headache, and muscle aches. Recurrences typically involve localized vesicles after prodromal symptoms (tingling and burning), which heal within a short period.

Treatment Methods

• General principles: Most mild cases of oral or genital herpes simplex heal spontaneously with symptomatic treatment (maintaining cleanliness and dryness, and relieving pain). Antiviral drugs are effective when started early after symptom onset (preferably within 48–72 hours), reducing the duration and severity of symptoms and the risk of complications.
• Medication treatment:
  • Topical agents: Acyclovir cream, etc. (for symptom relief in mild oral herpes).
  • Oral agents (common examples):
    • Acyclovir (oral): Used to treat primary or recurrent infections (the dose and duration are adjusted according to the circumstances).
    • Valacyclovir: Widely used for the treatment of primary and recurrent infections and for suppressive therapy. (The recommended dose for primary infection, recurrence, and suppressive therapy depends on the patient’s condition and applicable guidelines.)
    • Famciclovir: An alternative medication.
  • Severe or systemic infection, neurological complications, and neonatal infection: Hospitalization and treatment with intravenous acyclovir (e.g., 10 mg/kg IV q8h) are required.
• Suppressive therapy (when recurrences are frequent or quality of life is reduced): Long-term oral antiviral medication is continuously administered at a low dose to reduce the number of recurrences and the risk of transmission (the dose and duration are determined individually).
• Lifestyle management and precautions:
  • Avoid contact when lesions are present, especially sexual contact and contact with newborns.
  • Wash hands thoroughly after touching a lesion.
  • Visit a medical institution immediately if you are immunocompromised, pregnant, a newborn, or have accompanying central nervous system symptoms.
  • Dose adjustment is required in people with impaired kidney function and during high-dose or intravenous treatment.
  • Resistance to antiviral drugs is rare but may occur in immunocompromised people.

Checkpoints Before an Outpatient Visit (Including Example Questions)

• Items/information to prepare:
  • A list of currently prescribed or taken medications (including antiviral drugs) and a history of allergies
  • Previous similar symptoms (history of recurrence) and previous test results (viral tests, serology, etc.)
  • When and where the symptoms began (take photographs if possible) and changes in symptoms (fever, pain, neurological symptoms, etc.)
  • Possibility of pregnancy or current pregnancy status, and recent sexual contact history (if genital symptoms are present)
  • Conditions that may cause immunosuppression (anticancer drugs, immunosuppressants, HIV, etc.)
• Items to explain to the healthcare provider in advance during the outpatient visit:
  • When the symptoms occurred and their course (whether this is a primary infection or a recurrence)
  • Whether similar lesions were recently treated and the effect of treatment
  • Whether fever, headache, confusion, or visual disturbances (neurological symptoms) are present

General Example Questions to Ask the Doctor

• "What are the expected effects and common side effects of this medication (the recommended antiviral drug)?"
• "What is the prognosis for this outbreak, and how likely is it to recur?"
• "What lifestyle precautions should I take (such as protection from ultraviolet exposure and stress management)?"

Examples of Condition-Specific Questions

• "My recurrences are frequent. Is it appropriate to start suppressive therapy? When should it be started, and what is the expected duration?"
• "If genital herpes simplex is suspected or diagnosed during pregnancy, how will the mode of delivery (vaginal delivery vs. cesarean section) and treatment plan be determined?"