INFECTIONS IN PREGNANCY – HERPES SIMPLEX

CAUSATIVE ORGANISM:  Herpes Simplex Virus (HSV).

TRANSMISSION:   

    By physical contact, sexual contact, vertical.

RISK FACTORS: 

    Unprotected sex, immunosuppression (e.g. HIV), other STIs.

EPIDEMIOLOGY: 

    Herpes simplex infects 2% of pregnant women.

SYMPTOMS: 

    Burning sensation, pain, pruritis, dysuria (note: may be asymptomatic).

SIGNS: 

    Clusters of vesicles with surrounding erythema, can progress to ulcerated lesions which crust over, may be associated with local lymphadenopathy.

PATHOLOGY/PATHOGENESIS

DNA virus (herpes family), two types – HSV-1 is transmitted by oral-to-oral contact to cause oral herpes (which can include symptoms known as “cold sores”), but can also cause genital herpes.HSV-2 is a sexually transmitted infection that causes genital herpes. Both HSV-1 and HSV-2 infections are lifelong. Dormant period: Following primary infection, HSV remains dormant in nerve ganglia and can be reactivated to form recurrent lesions. Spread to neonate: Mainly direct contact with infected maternal secretions (but transplacental transmission possible), risk of neonatal transmission at vaginal delivery – 41% with primary lesions, 2% with recurrent lesions.

INVESTIGATIONS:

Usually diagnosed clinically. Microbiology: Swabs for viral culture/PCR, STI screen. Bloods: HSV antibody (primary infection in third trimester).

MANAGEMENT

Antenatal: Aciclovir (200 mg 5 times daily for 5 days) in primary infection. Treatment with acyclovir and valacyclovir by 36 weeks of pregnancy to term reduces the frequency of clinical manifestations, vertical transmission, elimination of the virus during birth by reducing the percentage of caesarean

Delivery with primary HSV: If within 6 weeks of likely delivery, advise Caesarean section. If opts for vaginal delivery, give IV aciclovir intrapartum, avoid prolonged ruptured membranes/FSE/FBS.

Delivery with recurrent HSV: Does not necessitate Caesarean section. Women may opt for Caesarean if lesions detected at onset of labour – can offer daily aciclovir from 36/40 to reduce likelihood of lesions.

COMPLICATIONS

Maternal: Disseminated herpes (encephalitis, hepatitis, disseminated skin lesions) rare but not uncommon in pregnancy.

Neonatal: It affects skin/eyes/mouth, CNS or multiple organs. The risk of neonatal infection varies from 30% to 50% for late onset HSV infections (last trimester), whereas early pregnancy infection carries a risk of about 1%. When primary HSV infection occurs during late pregnancy

PROGNOSIS:

•  HSV disease localized to the skin, eye, and/or mouth (SEM); this syndrome is associated with a low mortality but it has a significant morbidity, and it may progress to encephalitis or disseminated disease if left untreated;
• HSV encephalitis with or without skin, eye, and/or mouth involvement which causes neurologic morbidity among the majority of survivors; 
• Disseminated HSV which manifests as severe multiorgan dysfunction (including central nervous system, liver, lung, brain, adrenals, skin, eye, and/or mouth) and has a mortality risk that exceeds 80% in absence of therapy