HSV Transmission Through Intact Skin
HSV does not effectively transmit through truly intact, healthy skin without mucous membrane exposure. The virus requires direct contact with mucous membranes, compromised skin integrity, or access to deeper tissue layers to establish infection.
Primary Transmission Routes
HSV transmission occurs through specific pathways that bypass intact skin barriers:
Direct mucous membrane contact is the primary route, as HSV infects through oral secretions, genital fluids, or lesions contacting mucous membranes 1.
Compromised skin integrity is required for skin transmission, including dermatitis, abrasions, or open wounds 1.
Neonatal transmission occurs through exposure to infected maternal genital fluids during delivery or via invasive procedures that disrupt fetal skin integrity 1.
Evidence from Skin Barrier Studies
Recent ex vivo human skin infection studies provide direct evidence about HSV's inability to penetrate intact skin:
Intact skin samples completely prevented HSV-1 entry from the surface, with infection only occurring at sample edges where tissue integrity was lost 2.
Mechanical wounding surprisingly did not facilitate HSV-1 entry via the skin surface in ex vivo models, despite allowing latex bead penetration, suggesting additional barriers beyond physical structure prevent viral access to receptors 2.
Only when the dermis was removed could HSV-1 efficiently invade the basal epidermal layer, demonstrating that receptors are present but inaccessible through intact skin 2.
Exception: Pathological Skin Conditions
The only documented exception involves severely compromised skin barriers:
Atopic dermatitis skin with impaired barrier function allowed HSV-1 to penetrate and establish infection via the skin surface, which never occurred in healthy control skin 3.
IL-4/IL-13-induced inflammation alone was sufficient to create barrier defects allowing HSV-1 invasion in otherwise healthy skin samples 3.
This represents a special circumstance where multiple defective mechanical barriers and inflammation-altered tissue architecture make receptors accessible 3.
Clinical Risk Assessment Framework
The CDC guidelines for occupational exposure provide a practical framework applicable to HSV:
Intact skin exposure requires no follow-up unless contact is prolonged or involves a large skin area, which may warrant case-by-case evaluation 1.
Compromised skin integrity mandates follow-up, including any dermatitis, abrasion, or open wound exposed to potentially infectious material 1.
Mucous membrane exposure always requires evaluation as this represents the primary transmission route 1.
Important Clinical Caveats
Asymptomatic viral shedding occurs frequently (28% of days by PCR detection) from mucous membranes without visible lesions, making transmission possible even without obvious active infection 4.
Most transmissions to sexual partners and neonates occur during asymptomatic shedding periods rather than during symptomatic recurrences 4.
The distinction between "intact" and "compromised" skin can be subtle—microscopic breaks, chronic inflammation, or subclinical dermatitis may not be visually apparent but can facilitate transmission 3.