Varicella zoster virus infection is a common illness caused by a virus that stays in your body for life, even after you recover. This virus can cause chickenpox when you first get infected, and years later it may wake up again to cause shingles, a painful condition that affects the skin and nerves.

Understanding Varicella Zoster Virus

Varicella zoster virus, often called VZV, belongs to the same family of viruses as herpes. When you first encounter this virus, it typically causes chickenpox, which most people experience during childhood. The virus enters your body through your breathing passages or by touching the rash of someone who is infected. After you recover from chickenpox, the virus doesn’t leave your body completely. Instead, it travels to your nerve cells and settles there, staying quiet and inactive for years or even decades.^[1]

The unique characteristic of this virus is its ability to reactivate later in life. When the virus wakes up from its dormant state, it travels along the sensory nerves to your skin, causing a different condition called shingles or herpes zoster. This reactivation usually happens when your immune system becomes weaker, which can occur naturally as you age or due to certain illnesses and medications.^[1]

The virus can also cause several other health problems beyond chickenpox and shingles. These include infections of the brain or its protective covering, known as meningitis and encephalitis. When the virus affects the nerves around your eye, it causes eye shingles, and when it affects the facial nerves, it can lead to Ramsay-Hunt syndrome, which may cause temporary paralysis of the face muscles.^[1]

Epidemiology: How Common Are These Infections

Before the introduction of the chickenpox vaccine in 1995, varicella was extremely common in the United States. During the early 1990s, approximately four million people contracted chickenpox each year. Of these cases, between 10,500 and 13,000 people required hospitalization, and between 100 and 150 people died from complications. The vast majority of cases, more than 90 percent, occurred in children, though adults who contracted the illness often faced more severe symptoms.^[5]

Since the widespread use of the chickenpox vaccine, the situation has changed dramatically. The number of cases, hospitalizations, and deaths from chickenpox have all decreased by more than 90 percent. This represents a major public health achievement, though the disease still occurs, particularly in people who haven’t been vaccinated or who fall behind on their immunization schedule.^[4]

Shingles affects about one in three people during their lifetime. The individual risk of developing herpes zoster is estimated to be between 20 and 30 percent for the general population. However, this risk increases significantly with age. For people aged 85 and older, the risk rises to about one in two, meaning half of all people in this age group will experience shingles at some point.^[3]

The annual incidence of herpes zoster has been studied in various countries. In Sweden, research found approximately 315 cases per 100,000 people across all ages. For individuals 50 years of age or older, this number jumps to 577 cases per 100,000 people. In Switzerland, when the virus affects the central nervous system, the incidence rate is about 1.02 cases per 100,000 inhabitants.^[3]

The disease affects different racial groups at different rates. Studies have shown that Black individuals are about one-fourth as likely as white individuals to develop herpes zoster, suggesting that genetic factors may play a role in susceptibility to virus reactivation.^[4]

Causes and Transmission

Varicella zoster virus is a type of DNA virus that belongs to the herpesvirus group. It is highly specific to humans, meaning it only infects people and cannot be transmitted to or from animals. The virus can survive in the external environment for a few hours, but it is relatively fragile compared to some other viruses.^[3]

During a primary infection with chickenpox, the virus spreads through several routes. The most common way is through respiratory droplets that become airborne when an infected person coughs, sneezes, talks, or even breathes. You can also get infected by directly touching the fluid-filled blisters on someone’s skin or by touching objects that have been contaminated with fluid from these blisters.^[5]

The virus first enters through your respiratory tract and has an incubation period of 10 to 21 days, with the average being 14 to 16 days. This means that after you are exposed to the virus, it takes about two weeks before you start showing symptoms. During the incubation period, the virus multiplies in your tonsils and nearby immune tissues, then enters your bloodstream through your lymphatic system, which is the network of vessels that helps fight infections.^[3]

The virus then travels throughout your body, eventually reaching your skin where it causes the characteristic itchy rash. After you recover from chickenpox, the virus migrates to clusters of nerve cells called dorsal root ganglia in your spine, as well as the trigeminal nerve ganglia in your face. There it remains dormant, hidden from your immune system, sometimes for many decades.^[1]

When it comes to shingles, you cannot catch shingles directly from someone who has it. However, if you have never had chickenpox and have not been vaccinated, you can get chickenpox from someone with shingles. This happens primarily through direct contact with the shingles rash, though in some cases the virus particles from the rash can spread through the air. The risk of transmission from shingles is lower than from chickenpox, approximately 20 percent of the transmission risk compared to chickenpox.^[5]

Risk Factors

Several factors increase the likelihood of developing severe complications from varicella zoster virus infections. Understanding these risk factors helps identify people who need extra protection or more aggressive treatment.

Age is a significant risk factor, but it works differently for chickenpox versus shingles. For chickenpox, infants, adolescents, and adults tend to experience more severe illness than school-age children. Adults who get chickenpox face a higher risk of complications such as pneumonia, which is inflammation of the lungs. For shingles, the risk increases dramatically with age, particularly after 50 years old. This is because the immune system naturally weakens as we get older, making it harder to keep the dormant virus under control.^[4]

Pregnancy presents special concerns. Pregnant women who have never had chickenpox or the vaccine are at risk for severe illness if they become infected. If a woman develops chickenpox shortly before giving birth, specifically from five days before to two days after delivery, her newborn faces serious risk because the baby hasn’t had time to receive protective antibodies from the mother.^[5]

People with weakened immune systems face the highest risk of severe complications from both chickenpox and shingles. This group includes individuals with HIV/AIDS, cancer patients, people who have received organ transplants, and those undergoing chemotherapy. The immune system normally keeps the virus in check, so when immunity is compromised, the virus can cause widespread infection affecting multiple organs, which can be life-threatening.^[4]

Certain medications also increase vulnerability. Long-term use of corticosteroids, also called steroids, suppresses immune function. People taking immunosuppressive medications after organ transplants or for autoimmune diseases are at higher risk. Even short courses of high-dose steroids can temporarily increase susceptibility.^[1]

Chronic health conditions can make complications more likely. People with chronic skin disorders or long-term lung diseases are at increased risk for severe chickenpox. Those taking long-term aspirin therapy, such as some children with certain conditions, also face higher risk, though aspirin should never be given to children with chickenpox due to the danger of Reye syndrome.^[5]

For shingles specifically, stress appears to play a role in virus reactivation. Physical or emotional stress can temporarily weaken immune function, potentially triggering the dormant virus to reactivate. This explains why shingles sometimes occurs during periods of significant life stress or following other illnesses.^[1]

Symptoms

The symptoms of varicella zoster virus infections vary depending on whether you have chickenpox or shingles, and where in your body the virus is active.

Chickenpox Symptoms

Chickenpox often begins with mild symptoms before the rash appears. You might experience a slight fever, usually not very high, along with feeling tired and weak. Some people develop a mild headache or lose their appetite. These early symptoms typically start one to two days before the rash develops.^[7]

The hallmark of chickenpox is the distinctive rash. It usually starts on the face, scalp, and trunk, appearing as small pink or red spots. Within hours, these spots develop into fluid-filled blisters that look like tiny water balloons sitting on red skin. The blisters are intensely itchy, which is one of the most bothersome aspects of the illness. New waves of blisters continue to appear for several days, so you might have spots at different stages of development at the same time, some fresh and fluid-filled, others already drying out.^[7]

The blisters tend to be more numerous on covered parts of the body than on exposed areas. They can appear almost anywhere, including the scalp, armpits, trunk, and even inside the mouth, on the eyelids, or in the genital area. After a few days, the blisters break open, leak their fluid, and form scabs. The entire process from the first spot to the last scab typically takes about one to two weeks. Children usually develop between 250 and 500 blisters, though the number varies widely.^[3]

People who have been vaccinated may still get chickenpox, but it’s usually much milder. They typically have fewer than 50 blisters, less fever, and recover faster. Sometimes the blisters don’t even fill with fluid but remain as red bumps. This is called breakthrough varicella.^[5]

Shingles Symptoms

Shingles typically begins with pain, which may start several days before any rash appears. This pain often has a burning, tingling, or stabbing quality and is usually confined to one area on one side of the body. The pain can be severe enough that people sometimes mistake it for other conditions like heart problems, kidney stones, or appendicitis, depending on its location.^[8]

The shingles rash develops as a stripe or band of blisters that wraps around one side of the torso, or it may appear on one side of the face or neck. The rash follows the path of a single nerve or adjacent pair of nerves, creating a distinctive pattern called a dermatomal distribution. The affected skin is often extremely sensitive, even to light touch, and the blisters look similar to chickenpox blisters but are grouped together in the nerve pathway pattern.^[8]

Besides pain and rash, people with shingles may experience fever, headache, extreme sensitivity to light, and fatigue. Some people develop shingles pain without ever developing a visible rash, which can make diagnosis challenging.^[1]

Other Manifestations

When varicella zoster virus affects the eye area, causing herpes zoster ophthalmicus, symptoms include eye redness, swelling around the eye, pain in and around the eye, and sensitivity to light. This condition requires urgent medical attention because it can lead to vision problems if not treated promptly.^[1]

Ramsay-Hunt syndrome occurs when the virus reactivates in the facial nerve. In addition to the typical painful rash, this condition causes facial paralysis on one side, earache, and sometimes affects hearing or balance. The facial weakness can make it difficult to close the eye on the affected side or control the muscles around the mouth.^[1]

When the virus affects the brain or its covering, symptoms become more serious and include severe headache, confusion, difficulty staying awake, stiff neck, frequent vomiting, difficulty walking, and seizures. These symptoms require immediate emergency medical care.^[22]

Prevention

Prevention of varicella zoster virus infections relies primarily on vaccination, along with some practical measures to avoid exposure and transmission.

Vaccination

The chickenpox vaccine is the most effective way to prevent varicella infections. It contains a weakened form of the live virus that cannot cause serious disease but stimulates your immune system to produce protective antibodies. The standard recommendation is for children to receive two doses of the vaccine, with the first dose given between 12 and 15 months of age, and the second dose between 4 and 6 years of age.^[5]

The vaccine is highly effective, preventing severe disease in nearly all vaccinated individuals and preventing any illness in most cases. Even when vaccinated people do get chickenpox, it is typically very mild with fewer blisters and faster recovery. Some countries have adopted universal pediatric immunization programs, and these have dramatically reduced the burden of chickenpox in those populations.^[2]

For shingles, there is a separate vaccine recommended for adults aged 50 and older. This vaccine helps prevent shingles and, importantly, reduces the risk of developing postherpetic neuralgia, which is persistent pain that can last for months or years after the shingles rash heals. About 20 percent of people who get shingles develop this chronic pain condition, and it is particularly common and severe in older adults.^[14]

Post-Exposure Prevention

If you have been exposed to chickenpox or shingles and are at high risk for complications, there are measures that can prevent or reduce the severity of illness. Varicella zoster immune globulin, abbreviated as VariZIG, contains antibodies against the virus and can be given to high-risk individuals within 10 days of exposure, ideally within 4 days. This is particularly important for pregnant women without immunity, newborns, premature infants, and people with severely weakened immune systems.^[9]

People without evidence of immunity who are exposed to the virus can receive the chickenpox vaccine within 3 to 5 days of exposure. This can prevent the disease or make it milder if it does occur.^[17]

Preventing Transmission

If you or your child has chickenpox, staying home from school, work, or childcare is crucial. People with chickenpox are contagious from one to two days before the rash appears until all blisters have dried and formed scabs. For vaccinated individuals who develop lesions that don’t crust over, the contagious period lasts until no new lesions have appeared for 24 hours.^[5]

Practicing good respiratory hygiene helps prevent spread. Coughing or sneezing into a tissue or your elbow, disposing of tissues properly, and washing hands frequently with soap and water for at least 20 seconds can reduce transmission. Avoid sharing cups, utensils, or other items that might carry saliva or virus particles.^[7]

People with shingles should keep all lesions covered when possible. Healthcare workers and others with localized shingles should avoid contact with high-risk individuals, particularly pregnant women, premature infants, and people with weakened immune systems, until all lesions have crusted over.^[17]

Pathophysiology: What Happens in Your Body

Understanding what happens in your body during varicella zoster virus infections helps explain why symptoms occur and how complications can develop.

Primary Infection Pathway

When you first encounter varicella zoster virus, it enters your body through the mucous membranes of your respiratory tract or conjunctiva of your eyes. The virus quickly infects local immune cells and those in nearby lymphoid tissues like your tonsils. This initial phase occurs silently, without any symptoms.^[4]

From these initial sites, the virus spreads through your lymphatic system, which is a network of vessels and organs that play a key role in immune function. The virus multiplies extensively in lymph nodes and other lymphoid organs throughout your body. After this phase of multiplication, the virus enters your bloodstream in what is called viremia, meaning virus in the blood.^[10]

Through the bloodstream, the virus reaches your skin, where it infects the cells of small blood vessels. This infection causes the characteristic chickenpox rash. The virus damages the cells in the outer layer of skin, creating the fluid-filled blisters that contain high concentrations of infectious virus particles. The body’s immune response to this infection causes the redness, swelling, and intense itching that make chickenpox so uncomfortable.^[3]

Establishing Latency

While your immune system fights the active infection and you recover from chickenpox, some virus particles travel from the skin lesions backwards along sensory nerve fibers. These fibers are like electrical cables that carry sensation information from your skin to your spinal cord and brain. The virus follows these cables to reach the cell bodies of sensory neurons, which are located in clusters called ganglia near your spine and in your face.^[6]

In these nerve cell clusters, particularly the dorsal root ganglia in your spine and the trigeminal ganglion in your face, the virus establishes what is called latent infection. During latency, the virus essentially goes to sleep. It stays inside the nerve cells but doesn’t actively reproduce or cause symptoms. The virus DNA becomes part of the cell but remains relatively quiet, with only minimal viral activity. Your immune system cannot completely eliminate the virus during this latent phase because it is hidden inside nerve cells and produces very few viral proteins that the immune system could recognize.^[3]

Reactivation Process

Years or decades later, various triggers can cause the latent virus to reactivate. The most important factor is weakening of cell-mediated immunity, which is the part of your immune system that fights viruses inside cells. This weakening happens naturally with aging, which is why shingles becomes increasingly common in older adults. It also occurs with diseases that affect immune function, such as HIV/AIDS or cancer, and with medications that suppress immunity like chemotherapy or high-dose steroids.^[4]

When reactivation occurs, the dormant virus in the nerve ganglia begins reproducing again. The newly produced virus particles travel along the sensory nerve toward the skin area supplied by that nerve. This journey along the nerve causes the burning pain that often precedes the shingles rash by several days. The pain occurs because the replicating virus damages the nerve and causes inflammation along its path.^[14]

When the virus reaches the skin, it infects the cells there, causing the characteristic shingles rash in a band-like pattern that follows the path of the affected nerve. Unlike chickenpox, which spreads throughout the body, shingles typically affects only the skin area supplied by one or two adjacent nerves, usually on just one side of the body.^[8]

Complications Mechanisms

In some cases, particularly in people with severely weakened immune systems, the virus can cause more serious complications. If the virus spreads to multiple organs through the bloodstream, it causes disseminated disease, which can affect the lungs, liver, and brain. This widespread infection can be life-threatening.^[4]

When the virus reaches the brain, it can cause encephalitis. The virus infects brain cells directly and also triggers a strong immune response. The combination of viral damage and the body’s inflammatory response causes swelling in the brain, which is contained within the rigid skull. This swelling can increase pressure inside the head and damage brain tissue, leading to the serious symptoms of encephalitis such as confusion, seizures, and altered consciousness.^[22]

The persistent pain of postherpetic neuralgia occurs when the virus and the inflammatory response damage nerve fibers. This damage alters how the nerves function, causing them to send pain signals even when there is no ongoing injury. The damaged nerves may also develop increased sensitivity, so even light touch feels painful. These changes in nerve function can persist long after the virus has been cleared from the affected area.^[14]