Herpes Simplex Virus

Question 1

Define

Answer 1

DNA virus

 

Two types: 1 (oral>genital) or 2 (genital>oral)

Spread to neonate – through direct contact with infected maternal secretions (transplacental possible), risk of neonatal transmission at vaginal delivery is 41% with primary lesion or 2% with recurrent lesions

 

Question 2

Risk factors

Answer 2

Aetiology: physical/sexual contact; vertical

Risk factors: unprotected sex, immunosuppression, other STI

Factors influencing transmission:

• Type of maternal infection (primary or recurrent)
• Primary episode- 57% risk of neonatal infection
• First episode non-primary- 25% risk
• Recurrent episode(s)- 2% risk

Presence of transplacental maternal neutralising antibodies

Duration of rupture of membranes before delivery

Use of foetal scalp electrodes/ integrity of mucocutaneous barriers

Mode of delivery

• Vaginal- increased risk
• C-section- PREFERRED

Epidemiology: 2% of pregnant women

Question 3

Signs and Symptoms

Answer 3

Maternal:

• Asymptomatic
• Oral herpes
• Genital herpes (dysuria, frequency)
• Disseminated herpes (encephalitis, hepatitis, disseminated skin lesions)

IU HSV infection

• Microcephaly
• Encephalomalacia
• Hydranencephaly and/or intracranial calcification
• Scarring, active lesions, hypo- and hyperpigmentation
• Microphthalmia, retinal dysplasia, optic atrophy and/or chorioretinitis

 

Neonatal: 1 per 60,000 live births -> SEM (skin, eyes, mouth) , CNS ± SEM or disseminated infection:

Skin, Eye and Mouth (SEM) disease - 45%

• Blistering vesicular rash
• Chorioretinitis

CNS disease ± SEM 30%——— Mortality 6% (high morbidity)

• Seizures
• Lethargy
• Presents 10d-4w postpartum
• Irritability
• Poor feeding
• Temperature instability
• Bulging fontanelle

Disseminated infection involving multiple organs 25%——— High mortality (30%)

• Encephalitis (60-70%)
• CNS (60-75%)
• Hepatitis
• Pneumonitis
• No skin lesions (>20%)
• DOC

 

Question 4

Investigations

Answer 4

Clinical diagnosis ± STI screen

PCR virus

Question 5

Management

Answer 5

ACUTE INFECTION  Aciclovir (400mg, TDS):

• Maternal:
• <26w primary infection -> oral aciclovir; 36 weeks until delivery
• >26w primary infection -> oral aciclovir until delivery

Neonate:

• IV aciclovir to child (14d if SEM disease -> 21d if CNS or disseminated)

+ monitor neutrophil count

 

DELIVERY (primary infection):

1st episode ≥6w prior to EDD -> SVD

1st episode ≤6w prior to EDD -> C-section

Perform HSV (type-specific) antibody testing

 

If the woman chooses vaginal delivery:

• Rupture of membranes and invasive procedures should be avoided
• IV aciclovir given intrapartum to the mother (and the neonate)
• Avoid invasive procedures in labour (e.g. forceps delivery) -> increase risk of neonatal HSV

 

DELIVERY (recurrent episodes) -> SVD (only a 2% risk of transmission if recurrent; due to maternal IgG)

• Daily suppressive aciclovir 400mg TDS from 36 weeks’ gestation
• Avoid invasive procedures during labour if genital lesions (i.e. foetal scalp electrodes)

Question 6

Complications

Answer 6

Herpes is particularly dangerous when acquired around the time of delivery, with serious neonatal consequences

Premature rupture of membranes and preterm delivery

Prognosis -> neonatal mortality from 2% (local disease) to 50% (disseminated disease)

• Improved outcomes if early diagnosis and initiation of antiviral therapy