Human herpes virus 3 (HHV3) is also called varicella-zoster virus. HHV3 causes chickenpox. It can also cause a recurrent virus infection of the skin, which is called herpes zoster or shingles. Shingles occurs when dormant varicella-zoster virus from an initial bout of chickenpox becomes reactivated. Like its close relative, HHV1, herpes zoster likes to infect skin cells and nerve cells. This virus may also recur along nerve fibre pathways, causing multiple sores where nerve fibres end on skin cells. Because an entire group of nerve cells is often affected, shingles is generally much more severe than a recurrence of herpes simplex. The lesions generally appear in a band-like or belt-like pattern occurring on one side of the body and are often accompanied by itching, tingling, or even severe pain. Healing usually occurs in 2 to 4 weeks, and scars may remain. Postherpetic neuralgia is a complication of shingles where the pain associated with the infection can persist for months and even years. Most people who experience shingles once do not experience it again.
The risk of transmission from mother to baby is highest if the mother becomes infected around the time of delivery (30% to 60%), since insufficient time will have occurred for the generation and transfer of protective maternal antibodies before the birth of the child. In contrast, the risk falls to 3% if the infection is recurrent, and is 1–3% if the woman is seropositive for both HSV-1 and HSV-2, and is less than 1% if no lesions are visible. Women seropositive for only one type of HSV are only half as likely to transmit HSV as infected seronegative mothers. To prevent neonatal infections, seronegative women are recommended to avoid unprotected oral-genital contact with an HSV-1-seropositive partner and conventional sex with a partner having a genital infection during the last trimester of pregnancy. Mothers infected with HSV are advised to avoid procedures that would cause trauma to the infant during birth (e.g. fetal scalp electrodes, forceps, and vacuum extractors) and, should lesions be present, to elect caesarean section to reduce exposure of the child to infected secretions in the birth canal. The use of antiviral treatments, such as aciclovir, given from the 36th week of pregnancy, limits HSV recurrence and shedding during childbirth, thereby reducing the need for caesarean section.