Herpes

Herpes simplex type 1 (HSV‑1) is a widespread pathogen responsible for orolabial lesions. It is an enveloped, double-stranded DNA (dsDNA) virus belonging to the family Herpesviridae. Once the virus infects a host cell, its double‑stranded DNA genome is delivered into the nucleus, where a coordinated cascade of immediate‑early, early, and late gene expression directs viral DNA replication, structural protein synthesis, and virion assembly. After primary infection of epithelial cells, HSV-1 establishes latency in sensory neurons of the trigeminal ganglion. Reactivation, prompted by triggers such as stress or immunosuppression, results in recurrent mucocutaneous lesions.

Diagnosis

HSV‑1 infection is often recognized through characteristic lesions. Laboratory confirmation may involve polymerase chain reaction (PCR) testing, viral culture, or direct fluorescent antibody assays from lesion samples. Serologic testing for HSV‑1 antibodies has limitations—particularly for differentiating oral from genital infection—and is generally not used as the sole diagnostic approach. Clinical evaluation remains central, especially when lab tests are inconclusive.

Treatment

HSV‑1 is incurable, but antiviral agents such as acyclovir, valacyclovir, and famciclovir effectively reduce symptom severity and shorten outbreaks by targeting viral DNA polymerase. For recurrent episodes—such as herpes labialis—topical agents (e.g., penciclovir, docosanol) may be used, although oral therapy is generally more effective. Suppressive antiviral therapy may be considered in individuals with frequent recurrences.

Prevention

Transmission is likely during active lesions, though asymptomatic viral shedding can also transmit infection. Preventive measures include avoiding direct contact with active lesions, practicing good hygiene (e.g., handwashing), and avoiding sharing personal items like lip balm or utensils. During oral‑genital contact, using barrier methods (e.g., dental dams) may reduce the risk of transmission. There is currently no licensed vaccine for HSV‑1, although vaccine candidates are under investigation.