Herpes simplex

• The incidence of neonatal Herpes Simplex Virus (HSV) infection in the UK is 65 in 100 000 live births annually (1986 to 1991). Subsequent surveillance from 2004 to 2006 showed an approximate doubling of incidence.
• Neonatal herpes although rare is serious with high morbidity and mortality. It is classified into three subgroups in the infant depending on the site of infection:
  • Disease localised to the skin, eye and / or mouth
  • Local central nervous system (CNS) disease (encephalitis alone)
  • Disseminated infection with multiple organ involvement
• Disease localised to the skin, eye and / or mouth represent approximately 30% of neonatal infections and have the best prognosis. With appropriate antiviral treatment, neurological and / or ocular morbity is less than 2%
• Local CNS and disseminated infection represent approximately 70% of neonatal infections. With antiviral treatment, mortality from local CNS disease is around 6% and neurological morbity around 70%. Disseminated disease with antiviral treatment carries a 30% morality and 17% have long term neurological sequelae. Disseminated herpes is more common in preterm infants and occurs almost exclusively as a result of primary infection of the mother.
• Neonatal herpes may be caused by HSV-1 or HSV-2.
• Most cases of neonatal herpes occur from direct contact with infected maternal secretions, although in 25% of cases, a possible source of postnatal infection was identified, usually a close relative. Post natal infection may occur as a result of exposure to oro-labial herpes infection.
• Rarely congenital herpes may occur as a result of transplacental infection.
• Factors that may influence perinatal transmission include the type of maternal HSV infection (primary versus recurrent), the presence of transplacental maternal neutralising antibodies, duration of ruptured membranes, use of fetal scalp monitors and mode of delivery.
• The risk are greatest when a women acquires a new infection (primary genital herpes) in the third trimester, particular within 6 weeks of delivery, as viral shedding may persists and the baby likely to be born before the development of protective maternal antibodies.
• Although recurrent herpes is associated with a very low risk of neonatal herpes, recurrent herpes at the time of delivery, which is commonly asymptomatic or unrecognized, may cause localised forms of neonatal herpes: both local CNS disease and skin, eye and mouth infection.
• Disseminated herpes infection in adults is rare though it has been more commonly reported in pregnancy, particularly in the immunocompromised.
• Although aciclovir is not licensed for use in pregnancy, there is substantial clinical experience supporting its safety

All pregnant women presenting with a first episode of genital herpes should be seen by a senior clinician.

The following are salient points only - refer to https://www.bashh.org/guidelines for detail 

• • There is no evidence of an increased risk of spontaneous miscarriage with primary genital herpes in the first trimester.
  • There is no evidence that HSV acquired in pregnancy is associated with congenital abnormalities. 
  • Treatment should not be delayed and should be in line with the clinical condition and will usually involve the use of oral (or intravenous aciclovir) in standard doses (oral aciclovir 400mg three times daily usually for 5 days).
  • Paracetamol and topical lidocaine2% gel can be offered for symptomatic relief. 
  • The obstetrician needs to be informed this is a new infection in pregnancy, preferably in writing.
  • Women with suspected genital herpes who are having midwifery–led care should be referred for review by an obstetrician.
  • Providing delivery does not ensue within the next 6 weeks, the pregnancy should be managed expectantly and vaginal delivery anticipated.
  • Following first or second trimester acquisition daily suppressive aciclovir 400mg three times daily from 36 weeks gestation reduces HSV lesions at term and hence the need for delivery by caesarean section. It has also been shown to reduce asymptomatic viral shedding.

All pregnant women presenting with a first episode of genital herpes should be seen by a senior clinician.

The following are salient points only - refer to https://www.bashh.org/guidelines for detail 

• There is some evidence for increased peri-natal mortality (preterm labour, low birth weight, stillbirth) however the data are conflicting so no additional monitoring of the pregnancy is recommended.
• Treatment should not be delayed and should be in line with her clinical condition and will usually involve the use of oral (or intravenous aciclovir) in standard doses (oral aciclovir 400mg three times daily usually for 5 days).
• Usually women in the third trimester will continue daily suppressive acyclovir at 400mg three times daily until delivery.
• The obstetrician needs to be informed urgently and a plan made for delivery.
• Caesarean section is the recommended choice of delivery for all women presenting with the first episode of genital herpes in the third trimester, particularly within 6 weeks of expected delivery as the risk of neonatal transmission of HSV is very high at 41%.
• It can be difficult to distinguish between primary and recurrent HSV infections. In up to 15% of cases of women presenting as a first episode of clinical HSV, it will actually be a recurrent infection. Type specific HSV antibody testing (immunoglobulin G antibodies to HSV-1 and HSV -2) may be available from Colindale, London after discussion with local virology services. The presence of antibodies of the same type as the HSV isolated on genital swabs would confirm this episode to be a recurrence rather than a primary episode. However it may take 2-3 weeks for results of this test. It is therefore recommended that an initial plan of delivery should be based on the assumption that all first episodes are primary genital herpes. Interpretation of serology can be complicated; results should be discussed with virologists or genitourinary physician.
•  If vaginal delivery is unavoidable or where the mother opts for a vaginal delivery refer to RCOG guidance for further information.
• The neonatologist should be involved in advance of delivery.

The following are salient points only - refer to https://www.bashh.org/guidelines for detail

• • Women with recurrent genital herpes should be informed that the risk of neonatal herpes is low, even if lesions are present at the time of delivery (0-3% for vaginal deliveries).
  • There is no increased risk of preterm labour, premature rupture of membranes, fetal growth restriction or congenital abnormalities associated with women seropositive for HSV.
  • The majority of recurrent episodes of genital herpes are short lasting and resolve within 7-10 days without antiviral treatment.
  • Vaginal delivery should be anticipated in the absence of other obstetric indications for caesarian section.
  • Daily suppressive aciclovir 400mg three times daily should be considered from 36 weeks. There is insufficient evidence to determine whether this reduces the incidence of neonatal herpes: however it reduces viral shedding and recurrences at delivery so may reduce the need for caesarian section. The risks, benefits and alternatives to daily suppressive therapy should be discussed with women and prophylaxis initiated for women who desire intervention.
  • The increase from the standard suppressive dose of 400mg twice daily is recommended in view of the greater volume of distribution of the drug during pregnancy.

In 25% of cases of neonatal herpes a postnatal source may be responsible for infection. This is usually a close relative. All those with herpetic lesions who may be in contact with the neonate, including staff, should practice careful hand hygiene. Those with oral herpetic lesions (cold sores) should not kiss the neonate.

• Management of pregnant women with primary or recurrent genital lesions at onset of labour 
• Genital herpes in preterm prelabour rupture of membranes (before 37+0 weeks of gestation)
• Management of HIV positive women with HSV infection
• Management of neonate

All of the above scenarios are beyond the scope of this guidance. Refer BASHH guidance instead.