Varicella Zoster Virus and the Diseases It Causes

Most people associate chickenpox with a childhood memory of an itchy rash, a week at home, and perhaps some calamine lotion. What many do not realise is that the virus responsible for that childhood illness never truly leaves the body. It retreats into the nervous system and can resurface decades later as a far more painful condition called shingles. Understanding the varicella zoster virus, how it behaves, and what it can do helps you protect yourself and your family at every stage of life.

What Is Varicella Zoster Virus?

Varicella zoster virus (VZV) is a member of the herpes virus family. It is the single virus responsible for two distinct diseases. The first time you encounter VZV, it causes chickenpox (varicella), a highly contagious illness characterised by an itchy, blister-like rash. After the illness resolves, the virus does not leave the body. Instead, it travels into the sensory nerve roots of the spinal cord, where it remains dormant, sometimes for decades.

In some people, years or even decades later, the virus reactivates. This second episode is called shingles, or herpes zoster. It typically causes a painful, localised rash along a specific band of skin supplied by the affected nerve. Beyond chickenpox and shingles, VZV reactivation can occasionally affect the eyes, the facial nerves, and in rare cases, the brain and its surrounding membranes.

How Varicella Zoster Virus Spreads

VZV is one of the most contagious viruses known. Understanding how it spreads is key to limiting its transmission.

• Respiratory droplets: During a chickenpox infection, the virus spreads through the air when an infected person coughs or sneezes. You can inhale the virus even without direct contact.
• Direct contact with the rash: Touching the fluid from a chickenpox rash or a shingles rash can transmit the virus to someone who has not been previously infected or vaccinated.
• Airborne particles from blisters: During reactivation (shingles), tiny particles from the rash can sometimes carry the virus through the air in close proximity.
• From shingles to unvaccinated individuals: You cannot catch shingles from someone who has it. However, an unvaccinated person who has never had chickenpox can contract chickenpox through contact with an active shingles rash.

A person with chickenpox is contagious from about one to two days before the rash appears until all blisters have completely crusted over. During this window, isolation is essential to prevent spread, particularly to vulnerable individuals.

Causes of Varicella Zoster Infection

VZV infection occurs in two stages, each with a distinct trigger:

• Primary infection (chickenpox): Caused by first exposure to the virus, most commonly in childhood. The virus enters through the respiratory tract and spreads throughout the body, causing the characteristic chickenpox rash.
• Reactivation (shingles): After the primary infection, the virus lies dormant in the dorsal root ganglia of the spine or in the trigeminal nerve of the face. When the immune system is weakened or under stress, the virus can reactivate and travel along the nerve pathway to the skin, producing the shingles rash.
• No prior chickenpox needed for exposure: People who were vaccinated but never had natural chickenpox can still develop a milder form of the illness if exposed to the virus, though their symptoms are typically less severe.

Risk Factors for Severe Infection

While most healthy children recover from chickenpox without complications, certain groups are at higher risk of a more serious illness:

• Adults who contract chickenpox for the first time tend to experience more severe symptoms than children.
• People aged 50 and above are at significantly increased risk of shingles reactivation and its complications.
• Individuals taking immunosuppressive medications, such as those used after organ transplants or for autoimmune conditions.
• People living with conditions that weaken the immune system, including HIV, cancer, or those undergoing chemotherapy.
• Pregnant women, who face particular risks to themselves and their unborn baby.
• Newborns whose mothers contract chickenpox just before or after delivery.
• People under significant physical or emotional stress, which can temporarily suppress immune function.

Symptoms of Varicella Zoster Virus Infection

Symptoms differ depending on whether VZV is causing a primary infection or a reactivation.

Chickenpox symptoms:

• A widespread, intensely itchy chickenpox rash that begins as small red spots, progresses to fluid-filled blisters, and then crusts over. The rash typically starts on the face, chest, and back before spreading to the rest of the body.
• Fever, often mild to moderate.
• Fatigue and a general feeling of being unwell.
• Headache.
• Loss of appetite.

The chickenpox rash usually lasts seven to ten days from first appearance to complete crusting.

Shingles symptoms:

• Pain, burning, or tingling along a band of skin, often preceding the rash by several days.
• A localised shingles rash that appears as a stripe of blisters, typically on one side of the body or face, following the path of a single nerve.
• Sensitivity of the affected skin even to light touch.
• Fever and headache in some cases.
• In cases involving the eye area (herpes zoster ophthalmicus): eye redness, swelling, and sensitivity to light.
• In cases involving the facial nerve (Ramsay Hunt syndrome): ear pain, facial paralysis, and sometimes hearing changes.

Complications of Varicella Zoster

Most cases of chickenpox resolve without lasting effects. However, complications can occur, particularly in high-risk groups:

• Bacterial skin infections from scratching open blisters.
• Pneumonia, which can be serious in adults and immunocompromised individuals.
• Encephalitis, a rare but dangerous inflammation of the brain.
• Meningitis or meningoencephalitis, affecting the brain and its surrounding membranes.
• Dehydration, particularly in young children or those who develop sores in the mouth.
• Reye's syndrome in children given aspirin during a chickenpox illness (aspirin should be avoided in children with viral infections).

Shingles carries its own set of complications:

• Postherpetic neuralgia (PHN): Persistent nerve pain in the affected area that continues long after the rash has healed. This is the most common complication of shingles and can last for months or years.
• Vision loss: When shingles affects the eye (herpes zoster ophthalmicus), it can damage the cornea and threaten sight if not treated promptly.
• Hearing loss or facial paralysis: In Ramsay Hunt syndrome, VZV reactivation in the facial nerve can cause these serious effects.
• Bacterial superinfection of the shingles rash.

Varicella Zoster in Children

Chickenpox is primarily a childhood illness and is generally milder in children than in adults. Most children develop a moderate number of blisters, a low-grade fever, and some discomfort over the course of one to two weeks. Healthy children typically recover fully without complications.

That said, certain children are at higher risk of complications. Newborns, very young infants, and children with weakened immune systems can develop severe chickenpox that requires hospitalisation and antiviral treatment.

Children who have been vaccinated against chickenpox are either protected from infection or experience a significantly milder form if they do contract the virus. Learning to recognise chickenpox symptoms early helps parents seek appropriate care promptly and take steps to prevent spreading the illness to others.

Varicella Zoster in Adults

Chickenpox is less common in adults because most were exposed during childhood, but when it does occur in adults who missed the infection or vaccination, it tends to be considerably more severe. Adults with chickenpox are at greater risk of pneumonia, hospitalisation, and other complications compared to children.

Shingles, on the other hand, is predominantly an adult condition. Around one in three people will develop shingles at some point in their lifetime. The risk rises sharply after the age of 50 and continues to increase with age. Older adults are also more likely to develop postherpetic neuralgia, the persistent nerve pain that can follow a shingles episode and significantly impair quality of life.

Varicella Zoster in Pregnancy

Chickenpox during pregnancy poses risks to both the mother and the developing baby. Pregnant women are more likely to develop severe chickenpox with complications including pneumonia, which can be life-threatening.

The timing of infection during pregnancy also matters greatly for the baby. Chickenpox contracted in the first 20 weeks of pregnancy carries a small but real risk of foetal varicella syndrome, which can cause skin scarring, limb abnormalities, eye problems, and neurological damage in the baby.

If a pregnant woman develops chickenpox within five days of delivery or up to two days after, the newborn is at risk of severe neonatal chickenpox, as the baby has not yet received protective antibodies from the mother.

Pregnant women who have not had chickenpox and have not been vaccinated should avoid contact with anyone who has an active infection and seek immediate medical advice if they believe they have been exposed. Vaccination is not given during pregnancy, but women planning to conceive can be vaccinated beforehand.

How Varicella Zoster Is Diagnosed

In most cases, a doctor can diagnose chickenpox or shingles based on the characteristic appearance and distribution of the rash. However, laboratory confirmation is sometimes needed, particularly in atypical presentations or in immunocompromised patients.

• Clinical assessment: The doctor evaluates the appearance, location, and progression of the rash alongside the patient's symptoms and history of previous chickenpox or vaccination.
• Polymerase chain reaction (PCR) test: A highly sensitive test performed on fluid taken from the blisters or a swab of the rash. It detects the genetic material of VZV and is considered the most accurate diagnostic method.
• Direct fluorescent antibody (DFA) test: A rapid test using blister fluid or tissue to identify VZV antigens under a fluorescent microscope.
• Viral culture: A sample from the rash is used to grow the virus in a laboratory. This method takes longer than PCR but can confirm active infection.
• Blood tests for antibodies: VZV-specific IgM and IgG antibody tests can indicate whether someone is experiencing a current infection, has had a previous infection, or has developed immunity through vaccination.
• Imaging: In cases where neurological complications such as encephalitis or meningitis are suspected, brain imaging and a lumbar puncture may be needed.

Treatment for Varicella Zoster

There is no cure for VZV. Once in the body, the virus remains there for life. However, antiviral medications can reduce the severity and duration of both chickenpox and shingles, and are particularly important in high-risk individuals.

• Antiviral medications: Acyclovir, valacyclovir, and famciclovir are the main antivirals used. They work most effectively when started early, ideally within 72 hours of the rash appearing.
• Pain relief: Over-the-counter or prescription pain medications help manage the discomfort of both chickenpox and shingles.
• Soothing measures for chickenpox: Calamine lotion, cool baths, and antihistamines can help relieve itching. Keeping fingernails short and clean helps prevent secondary infection from scratching.
• Wound care: Keeping blisters clean and avoiding bursting them reduces the risk of bacterial skin infection.
• Corticosteroids: Occasionally used in combination with antivirals for severe shingles to reduce inflammation, though this is determined on a case-by-case basis.
• Postherpetic neuralgia management: Nerve pain following shingles may be treated with specific medications including certain antidepressants, anticonvulsants, or topical patches and creams, under medical supervision.

Varicella Zoster Vaccination

Vaccination is the most effective way to prevent both chickenpox and shingles.

• The chickenpox vaccine is given as part of routine childhood immunisation schedules and is highly effective at preventing infection or significantly reducing its severity.
• Adults who have never had chickenpox or been vaccinated can receive the vaccine.
• A shingles vaccine is recommended for adults aged 50 and above, regardless of whether they remember having had chickenpox. Even those who have already had shingles can benefit from vaccination to reduce the risk of recurrence.
• Vaccination not only protects the individual but also reduces the risk of transmission to vulnerable people who cannot be vaccinated, such as newborns and immunocompromised individuals.
• The vaccines are safe, well-studied, and are not given to pregnant women or people with severely compromised immune systems. Speak to your doctor about the most appropriate timing and type of vaccine for your circumstances.

When to See a Doctor

In many cases, chickenpox in healthy children can be managed at home with supportive care. However, seek medical advice if:

• You are an adult who has developed chickenpox for the first time.
• You are pregnant and have been exposed to or developed chickenpox.
• Your child has an underlying condition that weakens the immune system.
• The rash appears to be infected, with increasing redness, warmth, or pus.
• Symptoms of shingles appear, particularly in adults over 50 or those who are immunocompromised.
• The shingles rash involves the eye area or the face.

Seek emergency care immediately if you or anyone in your care develops:

• Confusion or altered mental state.
• A severe or persistent headache.
• A stiff neck.
• Sores on the eyes or sudden vision changes.
• Difficulty breathing.
• A very high fever that does not settle.
• Extreme difficulty waking up.

Conclusion

Varicella zoster virus is a lifelong companion that most people acquire in childhood, often without understanding the full picture of what it can mean later in life. Chickenpox is usually manageable, but shingles can cause considerable suffering, and in vulnerable individuals, both conditions can become serious. Vaccination remains the most powerful tool available for prevention, both in childhood and in later adulthood.

Staying proactive about your health is the best way to stay a step ahead. At Metropolis Healthcare, a comprehensive range of tests is available to support your wellbeing at every life stage, from immunity-related assessments to full body health checks. With home sample collection across a wide network of touchpoints, over 4,000 tests, accurate reports, and easy booking through the website, app, call, or WhatsApp, taking charge of your health has never been simpler.

Prevention starts with awareness. Make it count.

Frequently Asked Questions

Is Varicella Zoster Contagious?

Yes, varicella zoster virus is highly contagious. Chickenpox spreads through respiratory droplets and direct contact with the rash. A person with chickenpox is contagious from one to two days before the rash appears until all blisters have crusted over. Shingles itself cannot be passed from one person to another as shingles. However, someone who has never had chickenpox and is not vaccinated can contract chickenpox from direct contact with a shingles rash.

Can Varicella Zoster Be Prevented?

Yes. The most effective prevention is vaccination. The chickenpox vaccine is given as part of routine childhood immunisation and is highly protective. A shingles vaccine is recommended for adults aged 50 and over. Good hygiene practices, avoiding contact with infected individuals, and covering an active rash are also important measures to limit spread.

Can You Get Shingles Without Having Had Chickenpox?

Not through natural infection. Shingles is a reactivation of VZV that has already been present in your body since a prior chickenpox infection. If you have never had chickenpox or been vaccinated, you cannot develop shingles from VZV. However, in very rare cases, those who received the chickenpox vaccine may occasionally develop a mild form of shingles, as the vaccine contains a weakened form of the live virus.

How Long Does Chickenpox Last?

The chickenpox rash typically progresses over seven to ten days. It begins as small red spots, develops into fluid-filled blisters, and gradually dries out and crusts over. The entire illness, including fever and other symptoms, usually resolves within ten to fourteen days in otherwise healthy children. Adults and immunocompromised individuals may experience a more prolonged and severe illness.

Is Shingles Dangerous?

Shingles can be painful and debilitating, and it does carry the risk of serious complications. The most common is postherpetic neuralgia, which is persistent nerve pain that can last for months or years after the rash heals. Shingles affecting the eye can threaten vision, and in rare cases, the virus can affect the brain. People over 60 and those with weakened immune systems are at the greatest risk of severe disease and complications. Early antiviral treatment significantly reduces the severity and the risk of complications.

Does Vaccination Prevent Shingles?

Yes. The shingles vaccine significantly reduces the risk of developing shingles and, in those who do get it despite vaccination, greatly reduces the severity of the illness and the risk of postherpetic neuralgia. It is recommended for adults aged 50 and above, including those who have already had shingles. The vaccine does not guarantee complete protection but offers a meaningful and well-established reduction in risk.

References

Arvin AM. Varicella-zoster virus. Clin Microbiol Rev. 1996;9(3):361-381.

Gershon AA, Breuer J, Cohen JI, et al. Varicella zoster virus infection. Nat Rev Dis Primers. 2015;1:15016.

World Health Organization. Varicella and herpes zoster vaccines: WHO position paper. Wkly Epidemiol Rec. 2014;89(25):265-288.

Johnson RW, Alvarez-Pasquin MJ, Bijl M, et al. Herpes zoster epidemiology, management, and disease and economic burden in Europe: a multidisciplinary perspective. Ther Adv Vaccines. 2015;3(4):109-120.

Oxman MN, Levin MJ, Johnson GR, et al. A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults. N Engl J Med. 2005;352(22):2271-2284.

Gnann JW Jr, Whitley RJ. Herpes zoster. N Engl J Med. 2002;347(5):340-346.

Centers for Disease Control and Prevention. Chickenpox (Varicella): For healthcare professionals. CDC; 2023.