Herpes simplex virus (HSV) occurs worldwide and produces a variety of clinical manifestations, ranging from mild stomatitis to fatal disease.

Epidemiology

• Incidence 
  • HSV-1 - 70-80% seropositivity in U.S. adults
  • HSV-2 - 10-40% seropositivity in U.S. adults
• Transmission
  • HSV-1 - oral
  • HSV-2 - sexual

Organism

• DNA virus
• Types 1 and 2

Clinical Presentation

• Manifestations and clinical course of HSV depend on clinical site, age and immune status of host
• HSV type 2 more often causes recurrent genital herpes episodes than type 1
• Primary infections are usually longer in duration than reactive infections
• Common clinical syndromes
  • Gingivostomatitis
  • Recurrent herpes labialis
  • Keratitis
  • Conjunctivitis
  • Vesicular skin eruptions
  • Herpetic Whitlow
  • Aseptic meningitis
  • Primary and recurrent genital herpes
  • Visceral herpes (esophagitis, pneumonitis, hepatitis)
  • Encephalitis
  • Neonatal herpes

Treatment

• Suppressive therapy may be useful in treating repeated reactivation infections

Prevention

• Barrier contraception and daily suppressive therapy recommended to prevent infecting partner with genital herpes

Diagnosis

• Indications for testing
  •  Early diagnosis is important since treatment with antivirals may substantially alter course of HSV infections
    • Untreated herpes encephalitis and neonatal herpes are fatal in 70% of patients, with neurologic sequelae in most survivors
    • Disseminated disease, usually in immunocompromised patients, requires aggressive therapy
• Laboratory testing
  • Culture and nucleic acid amplification based methods are the most sensitive, specific and timely methods for diagnosis of acute lesions (e.g., vesicles, ulcers, inflammation of mucous membranes)
  • Antigen detection tests for HSV are extremely rapid, but only 80% sensitive in acute vesicular lesions and 60-75% sensitive in resolving lesions or asymptomatic shedding
  • PCR test recommended if:
    • Specimen is likely to have a low viral load (CSF in herpes encephalitis)
    • Cultures are negative
    • Patient has AIDS
    • Patient has recurrent meningitis
    • Infant has suspected neonatal herpes
    • Lesions are several days old and culture will likely be negative
  • HSV antibody titers are not particularly useful for rapid diagnosis of acute infections due to delay in obtaining test results
    • In primary HSV infections, significant IgG or IgM titer elevations do not occur for 10-14 days in mucocutaneous disease and 3-4 weeks in herpes encephalitis
    • In reactivated/recurrent infections, high titers of antibody are already in serum at episode onset and do not change during convalescence
    • IgM tests cannot accurately distinguish between HSV-1 and HSV-2 antibodies.  Only IgG tests can accurately distinguish between HSV-1 and HSV-2 antibodies. Therefore, IgM tests available are for HSV antibodies but not type specific for HSV-1 or HSV-2