Congenital and Neonatal Herpes Simplex Virus (HSV) Encephalitis

Route of spread: hematogenous and intraneuronal.

Dessinated infection: the principal organs involved are liver, brain, and adrenals; however, infection can affect other organs. The prognosis is poor.

Encephalitis: encephalitis can present as an isolated finding or as a component of multiorgan disseminated infection. Nearly one-third of all babies with neonatal HSV infection have only encephalitis. Babies with disseminated infection, but not those with encephalitis alone, often have skin vesicles. Other clinical manifestations include seizures (both partial and generalized), lethargy, irritability, tremors, poor feeding, temperature instability, bulging fontael, and pyradimal tract signs. CSF findings include increase in protein content and even subtle change in CNS may be associated with significant developmental abnormalities. Similar to adult cases, bilateral temporal lobes are affected.

Mortality: death occurs in about half the cases with localized CNS disease who are not treated and is usually related to involvement of the brain stem.

Clinical diagnosis: viral culture is definitive; PCR is fast, sensitive and specific; serologic test is not helpful. Virus is almost never detectable in CSF by culture.

Time of infection:

In utero infection: by transplacental infection and usually involves skin, brain, eye, liver, and adrenals. Manifestations include a triad of chorioretinitis, cuteus aplasia, and hydranencephaly and encephalomalacia. Infection at earlier embryonic stages will probably cause spontaneous abortion. Diagnostic criteria: babies with symptomatic congenital HSV disease are identified within the first 48 hours of life. Other congenital infections must be ruled out.
Intrapartum infection: accounts of about 80% of all congenital/perinatal infections. After direct exposure, viral replication in the newborn either remains limited to the portal of entry- namely, the skin, eye, or mouth- or will progress to involve various other organs, including the brain. Primary maternal HSV infection carries a much higher risk of transmission to fetus than a recurrent maternal infection.
Postnatal infection: The source of infection has not been adequately studied.