Microbiology · Human herpesviruses
Herpes simplex virus 2 !
- Virus
- Enveloped
- Contact
- Exam priority: high
A sexually transmitted virus that causes recurrent genital herpes and can infect a newborn during birth.
Updated 2026-11-01
Also called: HSV-2, genital herpes
At a glance
- Shape
- Icosahedral with tegument and envelope
- Genome
- Linear double-stranded DNA
- Envelope
- Enveloped
- Family
- Herpesviridae (alphaherpesvirus)
- Size
- About 150 to 200 nm
Morphology
- Same structure as HSV-1, with which it shares much of its genome
- Multinucleated giant cells with intranuclear inclusions in lesion scrapings
Transmission
- Sexual contact, often from a person without symptoms
- Perinatal: passage through a birth canal shedding virus
Reservoir: Humans
Isolation precautions
What the care team adds to standard precautions.
- Contact
- Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.
Virulence factors
- Latency in the sacral ganglia
- Recurs and sheds in the genital area more often than HSV-1
- Genital ulcers raise the risk of acquiring and passing on HIV
Diseases it causes
- Primary and recurrent genital herpes
- Neonatal herpes (skin, eye and mouth; central nervous system; disseminated) Congenital (TORCH) infections: syphilis, toxoplasmosis, CMV and Zika →
- Aseptic meningitis
Clinical picture
- Painful genital vesicles and ulcers, with inguinal lymphadenopathy
- The first episode can be severe, with fever, dysuria and neurologic involvement
- Neonatal risk is high when the mother acquires infection near delivery and low with known recurrent herpes
Diagnosis
- PCR (NAAT) of the lesion, typed as HSV-1 or HSV-2
- Type-specific serology when there are no lesions; IgM testing is not recommended
- In the newborn: PCR of surface swabs, blood and cerebrospinal fluid
Treatment
Acyclovir, valacyclovir or famciclovir for the first episode, recurrences or suppression; intravenous acyclovir in the newborn. Resistant strains are usually resistant to valacyclovir and often to famciclovir; foscarnet is then used.
Drug class only; doses and regimens are set by the clinician from the current guideline.
In Pharmacology:
Prevention
- Condoms and avoiding sex during active lesions
- Antiviral suppression late in pregnancy for mothers with recurrent herpes
- Cesarean delivery if genital lesions are present at the start of labor
- Contact precautions for a newborn with herpes and for disseminated or severe primary mucocutaneous disease
Test yourself
Think of the answer, then tap the question to see it.
When in pregnancy is genital HSV infection most dangerous for the newborn?
When the mother acquires it near delivery, because she has not yet passed protective antibodies to the baby.
Which precautions apply to a newborn with neonatal herpes?
Standard precautions plus contact precautions until the lesions are dry and crusted.
What is the preferred test for a genital ulcer suspected to be herpes?
PCR (nucleic acid amplification) of lesion fluid, with typing of the virus.
Related
Related conditions
← Back to the group: Human herpesviruses
Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Herpes simplex virus (WHO, 2024); Herpes - STI Treatment Guidelines (CDC, 2021); Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions (CDC, 2024).
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Representative model, for educational purposes only.