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Herpes Simplex Virus

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Only 30% of mothers whose infants have neonatal herpes have a history of symptomatic genital herpes. Any infant with vesicular lesion(s) must have investigations performed and have aciclovir treatment commenced regardless of maternal history.

  • Both HSV-1 and HSV-2 can cause neonatal infection. Around 85% of transmission occurs perinatally, 10% in the postnatal period and a small amount antenatally.
  • Intrapartum / post natal infection can become manifest up to 4-6 weeks of age: disseminated infection usually occurs in the first two weeks and can mimic bacterial sepsis; localised CNS or SEM (skin, eye, mucous membrane) disease usually becomes manifest during the second and third week.
  • The risk of HSV infection in an infant born vaginally to a mother with a first episode or primary genital infection is 33-50% (hence caesarean section usually performed) and such infant warrant aciclovir treatment once investigations have been performed.
  • The risk from recurrent genital HSV infection is 3-5% at most and empiric therapy is not recommended. Cultures can be taken at 24-48 hours if the infant is asymptomatic and aciclovir only initiated if HSV is identified.
  • Scalp electrodes must be avoided wherever there is suspicion of active HSV in the mother.
  • CNS infection may occur as an isolated condition or as part of disseminated multi-organ disease. In either situation brain involvement may become extensive and result in adverse outcome. Therefore, in infants presenting with seizures and no other apparent cause, Herpes Simplex Encephalitis should be considered and there should be a low threshold for aciclovir treatment pending the results of CSF PCR.


If these are on a baby with suspected HSV disease, then swabs of skin lesions and other sites should be for PCR, not culture. If doing surveillance of a non-symptomatic baby born to a mother with HSV, then culture is sufficient.

  1. Skin vesicles: swab for HSV PCR.
  2. Swabs from eyes, mouth / nasopharynx for HSV PCR
  3. WBCs (CPD or EDTA tube) for HSV PCR.
  4. CSF - cells, protein, glucose, culture, HSV PCR.
  5. FBC, LFTs
  6. Head MRI or EEG may assist in localizing disease but 40 % of babies with disseminated disease will not have CNS involvement so indication depends on individual cases
  7. Ophthalmology consultation.
  8. Consult Paediatric Infectious Disease Team


  • Contact isolation is required, especially if skin lesions present.
  • Isolate infants born vaginally to mothers with active genital infection for four weeks.
  • Room-in with mother in isolation if possible.
  • Advise mother re handwashing.

Observation / Surveillance

Known exposed infants require careful observation.

  • Take eye, mouth, nasopharyngeal +/- skin swabs at 24-48 hours for HSV culture
  • The family must be educated regarding the symptoms and signs of neonatal HSV.


  1. Guidance on management of asymptomatic neonates born to women with active genital herpes lesions. Kimberlin DW, Baley J; Committee on Infectious Diseases; Committee on Fetus and Newborn. Pediatrics. 2013 Feb;131(2):383-6. doi: 10.1542/peds.2012-3217

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Document Control

  • Date last published: 01 April 2014
  • Document type: Clinical Guideline
  • Services responsible: Neonatology
  • Owner: Newborn Services Clinical Practice Committee
  • Editor: Sarah Bellhouse
  • Review frequency: 2 years