Herpes Simplex Virus-1 (HVS-1)

Herpes simplex virus is an enveloped double stranded DNA virus that belongs to alpha herpes virus; there are two types, HSV-1 and HSV-2, with HSV-2 very rarely being seen in oral lesions (results in genital herpes)

Aetiology

  • Aquired in childhood
  • 70% of UK adults have been infected
  • Transmitted via infected oral secretions during close contact

Clinical presentation

Primary infection

  • May go unnoticed
  • May produce a severe inflammatory reaction with vesicle formation leading to painful ulcers (gingivostomatosis)
Primary gingivostomatis
  • Disease of preschool children, represents the worst end of spectrum of disease seen during primary HSV1 infection
  • Systemic upset - fever, local lymphadenopathy
  • Vesicles and ulcers on the lips, buccal mucosa, and hard palate
  • May take up to 3 weeks to recover
  • May spread beyond mouth
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Latent infection

  • The hallmark of all herpes viruses is the ability of viruses to establish latent infections that persist for the life of the individual
  • Latent virus may be reactivated from the trigeminal ganglion by stress, trauma, febril illnesses and UV radiation
  • This triggers the recurrent form of the disease known as herpes labialis ('cold sore')
  • Not all reactivations are symptomatic, and only 1/2 of infected people get clinical recurrences
  • Multiple cycles of latency and activation possible but natural history is for decreasing frequency
  • Oral herpetic lesions usually HSV-1, recurrent intra-oral lesions are rarely HSV
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Herpetic whitlow

  • HSV infection of the finger can occur by innoculation of the virus through a break in the skin barrier
  • Often misdiagnosed as baterial infection (drainage and antibiotics not necessary)
  • Occupational hazard of dentistry and anaethetics, can also occur in children at the time of primary oral infection through autoinoculation
  • Use of gloves essential in prevention
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Herpes simplex encephalitis

  • HSV-1 can cause sporadic cases of encephalitis with high rates of morbidity and mortality
  • Characterised by rapid onset of fever, headache, seizures, focal neurological signs, and impaired consciousness

Investigations

  • Obtain testing to confirm the diagnosis of HSV in patients who present with new mucosal or cutaneous lesions, or recurrent mucosal or cutaneous lesions of unclear aetiology
  • Swab of lesion in virus transport medium - detection of HSV DNA by PCR

Management

  • Antiviral medications e.g. acyclovir help to reduce the severity and frequency of symptoms, but cannot cure the infection