What Symptoms Does Disseminated Neonatal HSV Cause?

When neonatal herpes simplex virus (HSV) spreads beyond the skin, eyes, and mouth, it is known as disseminated disease. This means the virus has entered the bloodstream and is affecting major internal organs. The most common signs do not look like a typical herpes infection. Instead, the baby often develops a sepsis-like illness ^{[1] [2]}. Sepsis is a life-threatening condition caused by the body’s overwhelming response to an infection. Symptoms can include trouble breathing, abnormal temperature, poor feeding, and extreme sleepiness ^{[1] [3]}.

Notably, many babies with this severe form of the virus do not have any of the classic skin blisters ^{[1] [2]}. Because these signs overlap with bacterial infections, doctors typically test and treat for both bacterial sepsis and HSV at the same time ^[4].

What You Should Do Now

Disseminated neonatal HSV is a medical emergency that can progress rapidly.

• If your baby is at home: Call emergency services (911) or go to the nearest emergency department immediately if your newborn has difficulty breathing, cannot feed, is unusually hard to wake up, has a seizure, or has an abnormal temperature. Do not wait for blisters to appear or test results to come back.
• If your baby is already in the hospital: Alert your nurse or doctor immediately if you notice any sudden changes in your baby’s breathing, alertness, feeding, or skin color.

Signs by Organ System

Disseminated HSV can involve one or more of the following systems, though not every baby will experience every complication.

Liver Involvement (Hepatitis)
The virus can cause severe liver inflammation. Blood tests often show a marked elevation in liver enzymes called AST and ALT ^[5]. While abnormal enzymes show liver cell injury, doctors will also check blood glucose, bilirubin (which causes yellowing of the skin called jaundice), and clotting tests (like PT/INR) to see how well the liver is functioning ^[6]. In severe cases, the liver injury can progress to sudden liver failure ^[7], though not every abnormal enzyme result means liver failure will occur.

Central Nervous System (CNS) Involvement
Disseminated disease can also affect the brain and spinal cord, causing inflammation called encephalitis. Signs can include extreme sleepiness (lethargy), marked irritability, seizures, abnormal muscle tone, or pauses in breathing (apnea) ^[3]. However, a baby might not show obvious neurological signs even if the brain is involved ^{[8] [9]}. Doctors often test the cerebrospinal fluid (CSF) using a lumbar puncture (spinal tap) to check for the virus in the CNS, provided the baby is stable enough for the procedure ^[10].

Lung Involvement (Pneumonitis)
The virus can cause a viral lung infection that places extra strain on the respiratory system. The baby may breathe very fast, grunt, flare their nostrils, or need extra oxygen ^[11]. In severe cases, this may lead to complications like pulmonary hypertension, which is high blood pressure in the arteries of the lungs that makes it difficult for the blood to pick up oxygen ^[12].

Heart and Circulatory Issues
Critical illness from the infection can affect how well blood circulates. Complications can include low blood pressure, poor circulation (making the skin look pale or mottled), and weakness in the heart muscle (myocardial dysfunction) ^{[12] [13]}. In severe cases, blood vessels can become “leaky,” causing fluid to shift into the baby’s tissues, a complication known as capillary leak ^[12].

Blood and Bleeding Problems (Coagulopathy)
The infection can disrupt the blood’s ability to clot normally, a condition called coagulopathy ^[7]. This can involve prolonged clotting times, low levels of clotting proteins (like fibrinogen), and a drop in platelets—tiny blood cells that help stop bleeding (thrombocytopenia) ^[5]. One study of infants with invasive HSV found that 65% had low platelet counts ^[5], though the severity varies. Signs of abnormal clotting include easy bruising, tiny red dots on the skin (petechiae), or prolonged bleeding from places where blood was drawn ^{[7] [14]}.

What the Care Team Will Do

Because babies can become critically ill very quickly, doctors typically start intravenous (IV) antiviral medicine (acyclovir) immediately if they reasonably suspect HSV, even before diagnostic tests are finished ^{[15] [16]}.

What to Expect in the Hospital:

• Testing: The team will likely send swabs from the baby’s surface sites (like the mouth and eyes), blood tests, and a CSF sample to check for HSV DNA using a test called PCR ^{[10] [17]}. These tests help map the spread, but testing should not delay treatment.
• Monitoring: Acyclovir requires careful monitoring. The care team will closely track your baby’s kidney function, blood counts, and urine output, adjusting the medication dose based on their age, weight, and kidney health.
• Treatment Duration: For disseminated or CNS disease, the IV acyclovir course is commonly 21 days ^[18]. If the brain is involved, the team may repeat the CSF test before stopping the IV medication.
• Follow-up Care: After IV treatment is complete, many babies are prescribed an oral suppressive acyclovir medicine for about six months to improve neurological outcomes and prevent skin recurrences ^{[19] [20]}.