Varicella Zoster Virus - Symptoms, Diagnosis, and Treatment

Introduction:

Human alphaherpesvirus 3 (HHV-3), also known as varicella-zoster virus (VZV), is one of nine herpes viruses that infect humans. It is the cause of chickenpox (varicella) in children and young adults, as well as shingles (herpes zoster) in adults, but rarely in children. VZV infections are human-specific but can survive in the environment for a few hours.

VZV encephalitis, an acute neurologic disorder with potentially severe complications, affects about one in every 4000 children. Furthermore, immunocompromised children (for example, children receiving chemotherapy for leukemia or advanced HIV (human immunodeficiency virus)infection) can develop disseminated VZV infection, which can be fatal.

VZV multiplies in the lungs, resulting in a wide range of symptoms. The virus remains dormant in the nerves after the primary infection (chickenpox), including the cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia. VZV can reactivate many years after a person has recovered from chickenpox which causes neurological conditions.

How Does VZV Affect Humans?

VZV is a human alphaherpesvirus that causes varicella (chickenpox) as the initial infection and lives in the sensory ganglia as a latent virus. Respiratory droplets or contact with viruses in varicella or zoster skin lesions transmit infectious viruses. VZV in respiratory or conjunctival mucosal cells can interact with and infect local immune system cells and neighboring lymphoid tissues. The chickenpox rash appears after 10 to 21 days of incubation.

The host immunologic mechanisms usually prevent virus replication. However, if the host immune system is compromised, reactivation may occur. This could be due to medications, illness, malnutrition, stress, or the natural decline in immune function that occurs with aging. When the virus is reactivated, it migrates along sensory nerves, causing sensory loss, pain, and other neurologic complications. If motor nerve roots are also involved, weakness, in addition to sensory changes, can develop.

What Are The Signs And Symptoms Of VZV Infections?

1. Chickenpox: Chickenpox begins with a blister-like skin rash and fever. Chickenpox can appear anywhere between 10 and 21 days after exposure. Sores frequently appear in groups, with different stages (bumps, blisters, and sores) present simultaneously. Blisters typically scab over five days. Chickenpox is contagious for one to two days before the rash appears and until all blisters have formed scabs. Children with weakened immune systems may experience blisters for an extended period. Adults without natural or vaccine-induced immunity to VZV can also get chicken pox. Severe pneumonia and other serious complications can occur in adults.

2. Herpes Zoster (Shingles): The vesicular shingles rash is the most common presentation. The first symptoms of VZV infection are usually pain and paresthesia. Diagnosis may be difficult until the characteristic vesicular rash appears. A prodromal period with varying symptoms is common. Within 24 hours of a prodromal illness of pain and paresthesias, red macules and papules develop and progress to vesicles. The most common symptoms are pain and sensory loss. However, motor weakness can also occur and is frequently overlooked on examination.

Early symptoms include:

• Fever.

• Chills.

• Headache.

• Feeling tired.

• Light sensitivity.

• Stomach upset.

Other symptoms that appear a few days after the initial symptoms include:

• Itching, tingling, or burning sensation in a specific skin area.

• Skin redness in the affected area.

• Raised rash.

• Fluid-filled blisters that break open and then scab over.

• Mild to severe pain in the affected skin area.

3. Zoster Multiplex:

• Shingles can appear on either side of the body in multiple dermatomes, both contiguous and noncontiguous.

• Individuals with compromised immune systems are more vulnerable.

• The term used depends on the number of dermatomes involved and whether the condition is unilateral or bilateral (e.g., zoster duplex unilateralis refers to the involvement of two unilateral dermatomes).

• There have been reports of zoster cases occurring in seven noncontiguous dermatomes at the same time.

4. Zoster Sine Herpete:

• VZV infection can reactivate without skin vesicles. These patients have severe dermatomal pain, motor weakness, and numbness, but no visible rash or vesicles.

• VZV infection can cause acute peripheral facial palsy in 8 to 25 percent of patients who do not have skin lesions. This is more common in immunocompromised patients who take Acyclovir (or other anti-zoster medications).

5. Central Nervous System (CNS) Diseases:

VZV continues to affect the CNS, with meningitis being the most common clinical manifestation. In addition, CNS VZV disease frequently presents without a zoster rash.

6. Ramsay-Hunt Syndrome:

• A peripheral facial palsy.

• Pain in the ear and face.

• Vesicles in the ear canal.

7. Keratitis (Herpes Ophthalmicus):

It is caused by the reactivation of VZV infection in the trigeminal nerve's ophthalmic division. It often presents as conjunctivitis or corneal ulcers. Vesicles on the skin may not be present.

Are Varicella Zoster Virus Infections Serious Illnesses?

The symptoms may be more severe in newborns, people with weakened immune systems, and adults. Serious complications can arise, including pneumonia (both bacterial and viral), brain infection (encephalitis), and kidney disorders. Many people are unaware that, before the availability of the vaccine, approximately 10,600 people were hospitalized, and 100 to 150 died in the United States each year due to chickenpox.

How Are VZV Infections Diagnosed?

Chickenpox or herpes Zoster is typically diagnosed clinically. The most dependable and sensitive method for detecting VZV DNA (deoxyribonucleic acid) is polymerase chain reaction (PCR). Direct immunofluorescence (DFA) to detect VZV antigen is the second option; PCR sensitivity is around 60 to 70 percent. The viral culture of VZV is possible, but it is insensitive, time-consuming, and expensive because special media may be required.

Other tests like MRI (magnetic resonance imaging) and a lumbar puncture can be used to detect major complications like encephalitis, meningitis, etc.

How Are VZV Infections Treated?

• Antiviral medications reduce the duration of symptoms and the likelihood of post-therapeutic neuralgia, especially when started within two days of the onset of the rash. In otherwise healthy patients with typical cases, oral Acyclovir may be prescribed. Other medications (e.g., Valacyclovir, Penciclovir, Famciclovir) may reduce the duration of the patient's pain when compared to oral Acyclovir.

• Varicella zoster immune globulin (VariZIG) is recommended for high-risk individuals within ten days (ideally within four days) of VZV exposure.

How To Prevent VZV Infections?

Vaccines against chickenpox and shingles are now widely available. Getting vaccinated is the best and most effective way to prevent VZV infections.

• Chickenpox Vaccine: The centers for disease control and prevention (CDC) advises children under 13 years to get two doses of the vaccine. They should receive their first dose between the ages of 12 and 15 months and their second dose between the ages of 4 and 6. The CDC advises people over 13 years who have never had chickenpox or a vaccine to receive two doses at least 28 days apart. Varivax and ProQuad are the two licensed vaccines for chickenpox.

• Shingles Vaccine: The CDC recommends that healthy adults over 50 receive two doses of the Shingrix shingles vaccine. Shingrix is more than 90 percent effective in preventing shingles and the long-term nerve pain that can accompany shingles.

Conclusion:

Varicella zoster viruses are highly infectious viruses of the herpes virus family that affect humans. The most common know infections of the virus are chickenpox and shingles. These can be prevented by being up to date on the vaccination. The CDC recommends the chickenpox and shingles vaccine to prevent the effects of VZV infections.