What is Varicella-Zoster Virus (Chickenpox) ?
Chickenpox, also known as varicella, is a contagious illness caused by the varicella-zoster virus (VZV). This virus can cause two illnesses: chickenpox (usually in people with no immunity to the virus) and shingles (which can occur after a person with chickenpox recovers, and the virus reactivates). The main symptom of chickenpox is a skin rash that eventually forms small, itchy blisters that scab over. The rash usually begins on the chest, back, and face and later spreads to other areas. Other symptoms can include fever, fatigue, sore throat, and headaches. These symptoms generally last 5 to 7 days. Serious complications of chickenpox can include pneumonia, brain inflammation, and bacterial skin infections. Chickenpox tends to be more severe in adults than in children.
After you’re exposed to the virus, it takes about ten to 21 days for the symptoms to appear. Most people start having symptoms about two weeks after they’ve been exposed. Chickenpox spreads through the air when someone with the illness coughs or sneezes. It can also spread by touching a chickenpox blister or scab. People can spread chickenpox from about 1-2 days before they get the rash until all their chickenpox blisters have formed scabs. People with shingles can also spread chickenpox.
Doctors usually can tell if you have chickenpox by the symptoms you’re experiencing. If they’re not sure, they can confirm it by testing fluid or scabs from your blisters. They might also do a test to see if your body has ever made antibodies to fight the virus, which would mean you have immunity to chickenpox. Sometimes, people can get chickenpox again, but these second infections are usually less severe and often don’t cause symptoms.
A vaccine to prevent chickenpox was introduced in 1995 and has greatly reduced the number of chickenpox cases and complications. The vaccine prevents about 70% to 90% of infections and about 95% of severe chickenpox cases. It’s recommended that children routinely get the vaccine. If a child is exposed to chickenpox, getting the vaccine within three days can still help improve the child’s outcome.
What Causes Varicella-Zoster Virus (Chickenpox) ?
Chickenpox, also known as varicella, is caused by a type of herpes virus known as the varicella-zoster virus (VZV), which is found all over the world. Once this virus infects a person, it becomes dormant, which is a common trait of herpes viruses.
Chickenpox is usually caught by breathing in droplets in the air that contain the virus. This can happen if someone with the virus coughs or sneezes and you inhale the droplets they release. Because the virus is very contagious, it can spread quickly. The virus initially infects the upper airways, which are the passages in your body that transport air to your lungs. After about 2 to 6 days, the virus enters the bloodstream, and another wave of infection occurs about 10 to 12 days later. This is when the telltale spots or blisters of chickenpox emerge.
Your body will respond to the infection by producing several types of antibodies – essentially proteins your immune system uses to fight off the virus. These include IgA, IgM, and IgG antibodies. However, it’s the IgG antibodies that give you lifelong immunity to the virus, which means once you’ve had chickenpox, you cannot get it again.
Lastly, after the initial infection, the varicella-zoster virus moves to the nerve cells where it can stay dormant for many years and could reawaken later in life to cause shingles, a painful rash.
Risk Factors and Frequency for Varicella-Zoster Virus (Chickenpox)
Varicella, also known as chickenpox, is a disease that happens worldwide, causing around 7,000 deaths every year. This illness is common in children living in temperate climates, with most cases appearing in the winter and spring. In the United States, it results in over 9,000 hospitalizations each year. It is most commonly seen in children between 4 to 10 years old. In fact, about 90% of people get chickenpox at some point. A notable point is that if someone in a household gets it, others who get it after can have a more severe form of the disease. In tropical regions, older people are more likely to get chickenpox and it can result in more serious health issues. In adults, it often leads to deep pockmarks and more visible scars.
- Varicella happens all over the world and causes approximately 7,000 deaths each year.
- In temperate countries, it’s common in children and occurs mostly in winter and spring.
- In the U.S., it leads to over 9,000 hospitalizations every year.
- It’s most prevalent in children aged 4 to 10.
- About 90% people will get varicella in their lifetimes.
- People who catch it from someone in their household generally have a more severe case.
- In tropical regions, it often affects older people and can be more serious.
- In adults, it can result in deep pockmarks and prominent scars.
Signs and Symptoms of Varicella-Zoster Virus (Chickenpox)
Chickenpox is a common illness that is especially prevalent in adolescents and adults. It often begins with muscle aches, nausea, decreased appetite, and a headache, eventually followed by a rash, mouth sores, a general feeling of discomfort, and a slight fever. Sometimes, these symptoms can appear in the mouth before the skin rash even starts. However, in children, the illness might not show these early signs, and the first thing noticed could be a rash or mouth sores.
The typical chickenpox rash starts as tiny red dots on the face, scalp, body, upper arms, and legs. Over the span of 10 to 12 hours, these dots transform into small bumps, then blisters, then pustules, before finally turning into scabs. Unique to chickenpox, the rash progresses in waves, so spots in different stages—dots, bumps, blisters, and scabs—can appear simultaneously.
- Begins as tiny red dots
- Turns into small bumps
- Develops into blisters
- Progresses into pustules
- Finally forms scabs
At the blister stage, the rash can be very itchy. Blisters might even form on the palms, soles of feet, and genital area. Around this time, small, painful, and itchy ulcers might develop in the mouth and around the tonsils. These mouth sores can appear 1 to 3 days before the skin rash. All these symptoms show up between 10 to 21 days after exposure to the virus. Adults might experience a more extensive rash and longer fever than children, and are more likely to develop complications like pneumonia.
Interestingly, a person with chickenpox becomes contagious 1 to 2 days before any disease symptoms appear, due to the watery nasal discharge that contains the live virus. Most people recover from the infection in 2 to 4 weeks.
There are some complications associated with chickenpox, such as secondary bacterial infections that can lead to skin conditions like cellulitis, impetigo, or erysipelas. Immune-weakened individuals might develop a severe form of chickenpox that spreads throughout the body and can be fatal. Although rare, the illness can also lead to neurological complications, like Guillain-Barre syndrome or encephalitis. If a pregnant woman gets chickenpox, the virus can affect the fetus, who may develop chickenpox later or suffer from varicella congenital syndrome.
Testing for Varicella-Zoster Virus (Chickenpox)
Chickenpox is generally diagnosed based on its typical signs and symptoms. If verification is needed, doctors can examine fluid from the fluid-filled blisters, skin scrapings from open non-crusted sores, or blood tests. The purpose of these tests is to search for reactions in your body that show a recent infection.
PCR (Polymerase Chain Reaction) is a test with the highest accuracy rate and can be used for non-skin samples such as fluids from the lungs and spinal cord. Once popular, the Tzanck test has now been mostly replaced with direct fluorescent antibody testing. Although the fluid-filled blisters can also be cultured, the yield is not as high compared to PCR test.
The blood tests can identify whether you’re currently battling an infection (by detecting something called IgM) or whether you’ve had the infection previously and your body is now immune to it (by detecting something called IgG).
If a pregnant woman is suspected of having chickenpox, this can be confirmed using ultrasound, though doctors typically wait at least 5 weeks after the suspected infection before performing this test. Additionally, a DNA test using the amniotic fluid surrounding the baby in the womb can be performed. However, this test carries some risks, including the risk of miscarriage, which is higher than the risk of the baby developing chickenpox.
Treatment Options for Varicella-Zoster Virus (Chickenpox)
If you have been infected with varicella-zoster virus, also known as chickenpox, you’re typically asked to stay at home to prevent spreading the virus to others. Useful practices include keeping your nails short and wearing gloves to prevent scratching and the risk of additional infections.
Calamine lotion, which you can apply directly to your skin, may help with your itching. Washing daily with warm water can help to prevent extra bacterial infections. If you have a fever, you may be advised to take acetaminophen, a common over-the-counter pain reliever.
If you’re at risk of having complications from chickenpox, or have had significant exposure to it, your doctor could give you varicella-zoster immune globulin. This is a treatment that contains many antibodies to the varicella-zoster virus, which can help prevent you from getting sick.
In children, taking the antiviral drug acyclovir within 24 hours of the rash appearing can reduce symptoms by a day. However, this doesn’t lower complication rates and usually isn’t suggested for kids with normal immune systems.
For adults, who generally have more severe infections, antiviral drugs like acyclovir or valacyclovir might be recommended if they can be started within 24 to 48 hours of the rash appearing. Supportive measures like drinking lots of water and taking fever and allergy medicines are also useful. Antivirals are typically given to adults, including pregnant women, as this group is more likely to experience complications. Oral medication is usually suggested, however, in patients with weakened immune systems, they could be given by an IV.
Varicella-zoster immune globulin is sometimes used for people with weakened immune systems. Additionally, there has been a vaccine available since 1995. This vaccine has a high seroconversion rate, meaning it can potentially switch your immune system from being susceptible to the disease to being resistant to it. This immunity is usually long-lasting. Side effects from the vaccine are uncommon.
What else can Varicella-Zoster Virus (Chickenpox) be?
The conditions that a doctor might consider when diagnosing chickenpox could include:
- Insect bites
- Impetigo (a bacterial skin infection)
- Smallpox
- Drug eruptions (skin reactions to medications)
- Dermatitis herpetiformis (an itchy, blistering skin disease)
In order to determine whether it’s chickenpox or another condition, the doctor would take a close look at the symptoms and possibly run some tests.
What to expect with Varicella-Zoster Virus (Chickenpox)
The outlook for healthy children is generally very good. However, for individuals with weakened immune systems, the infection can cause a lot of health problems.
