Genital Herpes is Caused by a Double-Stranded DNA Virus
The virus responsible for painful clustered vesicles on the genitalia is herpes simplex virus (HSV), which is a double-stranded DNA virus, not a single-stranded RNA virus, retrovirus, or double-stranded RNA virus. 1, 2
Viral Classification and Characteristics
- HSV belongs to the Alphaherpesvirinae subfamily of the Herpesviridae family, which are all double-stranded DNA viruses 3
- The virus establishes lifelong latent infection in the sacral ganglia, remaining in a non-multiplying episomal form in neuronal nuclei during dormancy 1
- This DNA-based mechanism allows the virus to integrate into the host nervous system and periodically reactivate, causing recurrent outbreaks 1, 2
Clinical Presentation Confirming HSV Infection
The clinical picture described is pathognomonic for genital herpes:
- Clustered vesicles containing clear fluid with thousands of infectious viral particles are the hallmark presentation 1
- These vesicles progress through a characteristic sequence: redness → papules → vesicles → shallow ulcers/erosions → crusting → spontaneous healing without scarring 1
- The painful nature and clustered distribution on the genitalia strongly indicate HSV-1 or HSV-2 infection 2, 4
Why Other Viral Types Are Incorrect
- Single-stranded RNA viruses (like enteroviruses causing hand-foot-mouth disease) can cause genital vesicles but are far less common and typically occur in children with characteristic lesions elsewhere 5
- Retroviruses (like HIV) do not cause vesicular lesions; they integrate into host DNA but manifest differently 1
- Double-stranded RNA viruses (like rotavirus) cause gastrointestinal disease, not genital vesicular eruptions
Laboratory Confirmation Importance
- Laboratory confirmation should always be sought because clinical diagnosis alone leads to both false positive and false negative results 1, 6
- The most sensitive diagnostic method is PCR for HSV DNA from vesicular fluid, though viral culture and antigen detection are also acceptable 6, 4
- Proper specimen collection involves opening vesicles with a sterile needle and collecting fluid before rupture 1, 7
Common Diagnostic Pitfall
The key pitfall is assuming all genital ulcers are HSV without considering other causes like syphilis (Treponema pallidum), chancroid (Haemophilus ducreyi), or non-infectious etiologies like Behçet syndrome or inflammatory bowel disease 1. However, HSV is the most common cause of sexually acquired genital ulceration 1, and the vesicular presentation with laboratory confirmation makes this diagnosis definitive.