HSV-1 infection vs HSV-2 infection
How to tell HSV-1 infection and HSV-2 infection apart when a board question makes them look alike.
HSV-1 is classically oral/trigeminal/encephalitis; HSV-2 is classically genital/sacral/neonatal, with site overlap possible.
Side by side
HSV-1 classically causes oral herpes, gingivostomatitis, herpes labialis, keratitis, and temporal lobe encephalitis, though it can also cause genital disease.
HSV-2 classically causes genital herpes, recurrent painful vesicles/ulcers, aseptic meningitis, neonatal herpes, and sacral latency, though it can also infect oral sites.
HSV-1 is an enveloped double-stranded DNA herpesvirus that establishes latency classically in trigeminal ganglia.
HSV-2 is an enveloped double-stranded DNA herpesvirus that establishes latency classically in sacral ganglia.
Painful oral vesicles, dendritic corneal ulcers, temporal lobe MRI/CSF HSV PCR, and Tzanck multinucleated giant cells support HSV-1 patterns.
Painful genital vesicles/ulcers, recurrent outbreaks, aseptic meningitis, neonatal disseminated disease, and HSV PCR support HSV-2 patterns.
The trap
Anatomic site is a clue, not an absolute rule; PCR/typing can identify HSV-1 or HSV-2 when needed.
The repair move
For herpes simplex, use syndrome and latency site while remembering oral/genital overlap.
Try a free question
CoreAn adult has fever, altered mental status, focal seizures, temporal lobe abnormalities, and CSF PCR positive for HSV-1. Which diagnosis is most likely?
Show answer and explanation
Answer: A. HSV-1 encephalitis. Temporal lobe encephalitis with CSF HSV-1 PCR supports HSV-1 encephalitis.
Why the other choices are tempting
- B. HSV-2 classically causes genital herpes and aseptic meningitis rather than temporal lobe encephalitis.
- C. VZV shingles causes dermatomal vesicles.
- D. CMV retinitis causes retinal disease in profound immunosuppression.
- E. EBV mononucleosis causes fever, pharyngitis, posterior nodes, and splenomegaly.
Flashcards
Tap a card to flip it.
What encephalitis pattern supports HSV-1?
Temporal lobe encephalitis supports HSV-1.
What latency site is classic for HSV-1?
Trigeminal ganglion latency is classic for HSV-1.
Quick answers
What is the fastest way to tell HSV-1 infection from HSV-2 infection?
HSV-1 is classically oral/trigeminal/encephalitis; HSV-2 is classically genital/sacral/neonatal, with site overlap possible.
What is the key clue for HSV-1 infection?
HSV-1 classically causes oral herpes, gingivostomatitis, herpes labialis, keratitis, and temporal lobe encephalitis, though it can also cause genital disease.
What is the key clue for HSV-2 infection?
HSV-2 classically causes genital herpes, recurrent painful vesicles/ulcers, aseptic meningitis, neonatal herpes, and sacral latency, though it can also infect oral sites.
What is the common trap with HSV-1 infection vs HSV-2 infection?
Anatomic site is a clue, not an absolute rule; PCR/typing can identify HSV-1 or HSV-2 when needed.