Q. How can an inactive herpes carrier prevent mother to child transmission of the virus, during and after pregnancy?
If herpes is inactive, there is hardly any chance of transmission of herpes to child. Only if herpes genitalis is active at the time of delivery, then caesarean section is indicated. If you want to suppress an attack of herpes genitalis, then prophylactically, acyclovir 400 mg tds can be taken in the last month of pregnancy. However, acyclovir has not been approved by the FDA for use during pregnancy and is labelled a category C drug (to be used only if the potential benefit outweighs the risk).
In about 90% of cases, neonatal herpes is transmitted when an infant comes into contact with HSV - 1 or 2 in the birth canal during delivery. There is a high risk of transmission if the mother has an active outbreak, because the likelihood of viral shedding during an outbreak is high. There is also a small risk of transmission from asymptomatic shedding (when the virus reactivates without causing any symptoms).
HSV can be vertically transmitted to the infant during the antenatal, intranatal, or post natal periods.
Five percent of all cases of neonatal HSV infection result from in utero transmission. With primary infection, transient viremia occurs. HSV has a potential risk for haematogenous spread to the placenta and to the fetus. Haematogenous spread can produce a spectrum of findings similar to other TORCH (toxoplasmosis, other infections, rubella, cytomegalovirus infection, and herpes simplex)infections, eg, microcephaly, microphthalmia, intracranial calcifications, and chorioretinitis.
Intranatal infection accounts for the majority of infected infants and occurs from passage of the infant through an infected birth canal. Seventy-five to 90% of infants with neonatal HSV are born to asymptomatic mothers who have no history of HSV infection.
Postnatal transmission of HSV can occur through contact with infected parents or health care workers.
Primary HSV infection - Transmission rate of 50%
Nonprimary first-episode infection - Transmission rate of 33%
Recurrent infection or asymptomatic shedding - Transmission rate of 0-4%
The overall chance of neonatal infection from asymptomatic shedding in a woman with a history of genital HSV infection is estimated to be less than 4 in 10,000 (i.e. 1% risk of asymptomatic shedding multiplied by the [up to] 4% risk of transmission).