Neonatal Herpes Encephalitis - Symptoms, Diagnosis, Treatment, and Prevention

Introduction:

Neonatal herpes simplex virus is usually transmitted from the infected mother to the child at delivery. This disease affects one in every 3000 to 20000 live births. Almost 20 percent of pregnant women are infected with this virus at some point. The disease has a slow onset that progresses rapidly and causes severe neurological complications in infants.

What Is the Herpes Simplex Virus?

Herpes simplex virus (HSV) is a highly contagious virus that affects the oral and genital areas of the body. It is of two types -

• Herpes simplex virus 1 (HSV 1) spreads through oral-to-oral contact and causes lesions in the mouth known as cold sores.

• Herpes simplex virus 2 (HSV 2) is a sexually transmitted infection that causes genital herpes.

What Is Neonatal Herpes Encephalitis?

Herpes simplex virus infection in babies is known as neonatal herpes. Pregnant women with an infection from the herpes simplex virus can transmit the disease to the baby. Women who have acquired genital herpes during pregnancy are at the highest risk of transmitting the infection to the fetus. Neonates may acquire the infection in three ways -

1. Intrauterine (when the fetus is still developing in the uterus).

2. Perinatally (refers to a period sometime just before and after birth).

3. Postnatally (after the baby is born).

What Are the Different Forms of Neonatal Herpes?

Neonatal herpes simplex virus infection is classified into three clinical forms -

1. SEM Disease (Skin, Eyes, Mouth Disease) - This localized infection affects the skin, eyes, and mouth and is characterized by vesicular lesions of the skin, conjunctivitis (infection or inflammation of the outer membrane of the eyeball and the inner eyelid), and ulcers in the mouth or tongue.

2. CNS Disease or Central Nervous System Disease - The virus affects the central nervous system and presents itself as a neurological disease. This is a common sequela of neonatal herpes. Encephalitis is known as the inflammation and infection of the brain tissue. It may be caused due to viral or bacterial infections or inflammation due to autoimmune diseases (when the immune system of the body attacks its healthy cells). In neonates, encephalitis due to herpes may be fatal and lead to brain dysfunction.

3. Disseminated Disease - There is a development of fever, respiratory distress, liver problems, and sepsis syndrome (when the response of the body to an infection harms its tissues). Skin lesions and neurological symptoms may also be present.

What Are the Signs and Symptoms of Neonatal Herpes Encephalitis?

Babies who develop encephalitis post viral infection with herpes virus show various clinical features such as -

• Poor feeding or refusing to feed.

• Bulging of the fontanelle (soft spot in the skull of the baby).

• Lethargy.

• Irritability and cranky babies.

• Tremors (involuntary shaking of the limbs).

• Seizures (rapid, involuntary movements of the limbs accompanied by loss of consciousness).

• Unstable body temperature (patients may develop a high fever).

• Skin vesicles may also be present.

• Delay in the physical and mental development of the baby.

How Is Neonatal Herpes Diagnosed?

The following tests are carried out to diagnose neonatal herpes encephalitis -

• Serological Testing - This test helps identify the antibodies in the serum (clear plasma fluid without the clotting components) of affected patients. Serological testing can only identify past infections and cannot specify the site of infection in the body.

• Viral Culture - Isolating the herpes simplex virus from the skin lesions and growing in the culture medium (a solid or semi-solid material used to develop microorganisms in the laboratory). Scrapings or surface swabs of the blisters on the skin are transferred to the culture medium to confirm the presence of the virus. The virus may also be isolated from other sites such as blood, urine, cerebrospinal fluid (CSF- fluid present in the spinal space), stools, and rectum.

• PCR (Polymerase Chain Reaction) Amplification - This test helps determine the presence of the herpes simplex virus in the body and identifies the type of virus (HSV type 1 or HSV type 2).

• Electroencephalogram (EEG) - This test helps measure the electrical activity in the brain. It is an important tool in diagnosing neonatal herpes encephalitis.

• Imaging Studies - Brain imaging scans such as MRI (magnetic resonance imaging) help visualize the brain tissue for abnormalities.

• Others - Cerebrospinal fluid examination (CSF studies) may show pleocytosis (increase in white blood cell count in the presence of an infection)

How Is Neonatal Herpes Treated?

Previously, antiviral drugs were not routinely used to treat herpes simplex infections in babies. This resulted in a higher rate of deaths, and the affected children did not survive beyond the first year of life. In recent times, antiviral drugs have been the first line of treatment in treating this disease.

Antiviral Drugs -

Low doses of antiviral drugs are the treatment of choice in neonates with herpes simplex virus disease. They are easy to administer and well-tolerated by the patients. Patients with neurological symptoms due to herpes simplex virus also show better results with low-dose antiviral therapy. Antiviral drug therapy can be started immediately after the physician suspects symptoms of herpes simplex virus while awaiting the confirmatory diagnostic test results. Neurological symptoms can be controlled with long-term antiviral drug therapy. The side effect of this long-term antiviral therapy can be neutropenia (low levels of white blood cells).

Anti-Seizure Medications -

They are useful for controlling episodes of seizures (uncontrolled electrical brain activity) in children.

Supportive Care -

• It is important to keep the patient hydrated and maintain electrolyte balance. This is done by intravenous administration of fluids (sodium chloride and water). Long-term antiviral therapy may cause kidney failure, so adequate hydration is critical.

• Respiratory support (to maintain adequate levels of oxygen in the body).

• Alimentary support (gastric feeding tube is inserted into the stomach externally to ensure adequate nutrition is provided to the patient).

How to Prevent This Disease in Newborns?

• Pregnant women affected by the virus are put on antiviral drug therapy.

• The surgeon should opt for a cesarean section delivery in patients who have genital lesions present at the time of delivery. This will avoid contact of the newborn with the lesions reducing the chances of acquiring the infection during delivery.

• Giving oral antiviral drugs a few weeks before delivery to patients with genital herpes may reduce the need for a cesarean section.

• Neonates without any symptoms of herpes born to infected mothers should be screened for herpes simplex virus infection. It is a highly infectious disease, and it is challenging to prevent it from transmitting to newborns.

Conclusion:

Neonatal herpes encephalitis has a high mortality (death) rate and causes permanent neurological damage in patients who survive after treatment. Antiviral treatment must be started in high-risk cases while awaiting the diagnostic test results to improve the outcome. Prompt investigation is critical in diagnosing this disease to carry out further treatment.

Patients usually do not survive beyond the first year of life, and those who do may suffer permanent neurological complications.