Herpes simplex virus
aka HSV
Baltimore I (dsDNA) herpes virus alpha
Most genital herpes asymptomatic
Primary HSV = Infection when HSV1 and 2 IgG previously negative
Non-primary HSV = IgG positive 1 or 2, with seroconversion of the other
HSV 1 much high rate of vertical transmission than HSV2 (15% v 0.01% in recurrence)
Transmission:
Antenatal (5%): Spontaneous abortion, IUGR, preterm labour rare (<1%)
Peripartum (85%)
if episode during pregnancy
Screening speculum exam for active HSV lesions during all deliveries
If recurrence (Swab pos for IgG pos type) > maternal antibodies provide some protection (see rate above)
If primary/non-primary = swab positive when IgG neg for same type, risk depends of timing of seroconversion
- prior to 30-34/40 = as for recurrence
- later = 25-50% transmission
Prevention of transmission
Consider oral aciclovir 400mg po tds (or valaciclovir 500mg po bd) from 36/40 for all except solitary episode prenatally, 1st or 2nd trimester
Avoid invasive intervention during labour
If new (primary/non-primary) infection in last trimester OR lesions noted during labour > LSCS
If virus in genital tract
Baltimore I (dsDNA) herpes virus alpha
Most genital herpes asymptomatic
Primary HSV = Infection when HSV1 and 2 IgG previously negative
Non-primary HSV = IgG positive 1 or 2, with seroconversion of the other
HSV 1 much high rate of vertical transmission than HSV2 (15% v 0.01% in recurrence)
Transmission:
Antenatal (5%): Spontaneous abortion, IUGR, preterm labour rare (<1%)
Peripartum (85%)
if episode during pregnancy
- Swab for PCR and culture
- Bloods for type specific serology
Screening speculum exam for active HSV lesions during all deliveries
If recurrence (Swab pos for IgG pos type) > maternal antibodies provide some protection (see rate above)
If primary/non-primary = swab positive when IgG neg for same type, risk depends of timing of seroconversion
- prior to 30-34/40 = as for recurrence
- later = 25-50% transmission
Prevention of transmission
Consider oral aciclovir 400mg po tds (or valaciclovir 500mg po bd) from 36/40 for all except solitary episode prenatally, 1st or 2nd trimester
Avoid invasive intervention during labour
If new (primary/non-primary) infection in last trimester OR lesions noted during labour > LSCS
If virus in genital tract
- LSCS
- no scalp electrodes