Complications:

Chickenpox (varicella) rarely causes complications, but it is not always harmless. It can cause hospitalization and, in rare cases, death. Fortunately, since the introduction of the vaccine in 1995, hospitalizations have declined by nearly 90%, and there have been few fatal cases of chickenpox.

Adults have the greatest risk for dying from chickenpox, with infants having the next highest risk. Males (both boys and men) have a higher risk for a severe case of chickenpox than females. Children who catch chickenpox from family members are likely to have a more severe case than if they caught it outside the home. The older the child, the higher the risk for a more severe case. But even in such circumstances, chickenpox is rarely serious in children. Other factors put individuals at specifically higher risk for complications of chickenpox.

Recurrence of Chickenpox and Reactivation as Shingles

Recurrence of Chickenpox. Recurrence of chickenpox is possible, but uncommon. One episode of chickenpox usually means lifelong immunity against a second attack. However, people who have had mild infections may be at greater risk for a breakthrough infection later on.

Reactivation of the Virus as Shingles (Herpes Zoster). The major long-term complication of varicella is the later reactivation of the herpes zoster virus and the development of shingles. Shingles occurs in about 20% of people who have had chickenpox.

Specific Complications of Chickenpox (Varicella)

Aside from itching, the complications described below are very rare.

Itching. Itching, the most common complication of the varicella infection, can be very distressing, particularly for small children. Certain home remedies are available that can alleviate the discomfort. [See: "Treatment for Chickenpox" section below.]

Secondary Infection and Scarring. Small scars may remain after the scabs have fallen off, but they usually clear up within a few months. In some cases, a secondary infection may develop at sites which the patient has scratched. The infection is usually caused by the bacteria Staphylococcus aureus or Streptococcus pyogenes. Permanent scarring may occur as a result. Children with chickenpox are at much higher risk for this complication than adults are, possibly because they are more likely to scratch.

Ear Infections. Some children are at higher risk for ear infections from chickenpox. Hearing loss is a very rare result of this complication.

A middle ear infection is also known as otitis media. It is one of the most common of childhood infections. With this illness, the middle ear becomes red, swollen, and inflamed because of bacteria trapped in the eustachian tube.

Bacterial Superinfection. Bacterial superinfection of the skin caused by group A streptococcus is the most common serious complication of chickenpox (but it is still rare). The infection is usually mild, but if it spreads in deep muscle, fat, or in the blood, it can be life threatening. Infection can cause serious conditions, such as necrotizing fasciitis (the so-called flesh-eating bacteria) and toxic shock syndrome (TSS).

Symptoms include:

• A persistent or recurrent high fever
• Redness, pain, and swelling in the skin and the tissue beneath

Pneumonia. Pneumonia is suspected if coughing and abnormally rapid breathing develop in patients who have chickenpox. Adults and adolescents with chickenpox are at some risk for serious pneumonia. Pregnant women, smokers, and those with serious medical conditions are at higher risk for pneumonia if they have chickenpox. Oxygen and intravenous acyclovir are key treatments for this condition. Pneumonia that is caused by varicella can result in lung scarring, which may impair oxygen exchange over the following weeks, or even months.

Effects on the Brain and Central Nervous System.

• Inflammation in the Brain. Encephalitis and meningitis, infections or inflammation in the central nervous systems, have occurred in a few varicella patients, both children and adults. This condition can be very dangerous, causing coma and even death. Fortunately, it is extremely rare. Symptoms vary. The patient may become over-agitated or may exhibit loss of coordination and poor balance.
• Stroke. Although stroke in children is extremely rare, a condition called cerebral vasculitis, in which blood vessels in the brain become inflamed, has been associated with varicella-zoster. Varicella may be a factor in some cases of stroke in young adults.

Effects During Pregnancy. The risk for chickenpox in a pregnant woman is very low (1 - 7 cases in 10,000). However, chickenpox places the woman at risk for life-threatening pneumonia. Infection in the pregnant woman in the first trimester also poses a 1 - 2% chance for infecting the developing fetus, which is an extremely serious condition. (Herpes zoster is even rarer in pregnant women, and there is almost no risk for the unborn child in such cases.)

Disseminated Varicella. Disseminated varicella, which develops when the virus spreads to organs in the body, is extremely serious and is a major problem for patients with compromised immune systems. An immune system may become compromised as a result of diseases such as AIDS, inherited conditions, or certain drugs. For example, disseminated varicella occurs in up to 35% of children with chickenpox who are undergoing cancer chemotherapy. In such cases, mortality rates are between 7 - 30%.

Reye Syndrome. Reye syndrome, a disorder that causes sudden and dangerous liver and brain damage, is a side effect of aspirin therapy in children who have chickenpox or influenza. The disease can lead to coma and is life threatening. Symptoms include rash, vomiting, and confusion beginning about a week after the onset of the disease. Because of the strong warnings against children taking aspirin, this condition is, fortunately, very rare. Children should never be given aspirin when they have a viral infection or fever. Acetaminophen (Tylenol) is the preferred drug for fever or pain in patients younger than age 18 years.

Other Rare Complications of Chickenpox. Other extremely rare complications of varicella include problems in blood clotting and inflammation of the nerves in the hands and feet. Inflammation can also occur in other areas of the body, such as the heart, testicles, liver, joints, or kidney.

Complications of Shingles (Herpes Zoster)

Pain. The pain and discomfort of the active herpes zoster infection is the primary symptom and complication of herpes zoster. The pain usually takes one of these forms:

• Continuous burning or aching pain
• Periodic piercing pain
• Spasm similar to electric shock

Such experiences may also be more intense than even normal responses, defined in the following ways:

• Allodynia is pain caused by factors, such as a light touch of clothing or a cold wind, which occurs from very little stimulation.
• Hyperalgesia is a more intense painful response to a normally painful experience.

The pain tends to be more severe at night. Temperature changes can also affect pain. The pain may extend beyond the areas of the initial zoster attack. In most cases, it does not affect daily life. Rarely, however, the pain of herpes zoster affects sleep, mood, work, and overall quality of life. This can lead to fatigue, loss of appetite, depression, social withdrawal, and impaired daily functioning.

Itching. Many patients report itching (postherpetic itch) as the primary symptom, rather than pain. In rare cases, it can be disabling.

Postherpetic Neuralgia (PHN). Postherpetic neuralgia (PHN) is pain that persists for longer than a month after the onset of herpes. It is the most common severe complication of shingles. It is not clear why PHN occurs. Some theories for its development are:

• The herpes zoster virus appears to produce persistent inflammation in the spinal cord that causes long-term damage, including nerve scarring.
• Nerves that are injured in the initial attack may heal abnormally and provoke an exaggerated response in the brain that produces intense sensitivity or pain.

In people with herpes zoster, the risk of developing PHN ranges from 10 - 70%. In general, however, the risk is likely to be in the lower range. People with impaired immune systems do not seem to be at any higher risk for persistent PHN than those with normal immune systems.

The following are risk factors for PHN:

• Age. PHN affects about 25% of herpes zoster patients over 60 years old. The older a person is, the longer PHN is likely to last. It rarely occurs in people under age 50.
• Gender. Some studies suggest that women may be at slightly higher risk for PHN than men.
• Severe or Complicated Shingles. People who had prodromal symptoms or a severe attack (numerous blisters and severe pain) during the initial shingles episode are also at high risk for PHN. The rate is also higher in people whose eyes have been affected by zoster.

In most cases, PHN resolves within 3 months. Some doctors define persistent pain after a herpes zoster attack as subacute herpetic neuralgia if it lasts between 1 - 3 months and as PHN only if it lasts beyond 3 months. Studies report that only about 10% of patients experience pain after a year. Unfortunately, when PHN is severe and treatments have not been very effective, the persistent pain and abnormal sensations can be profoundly frustrating and depressing for patients.

Secondary Infection in the Blisters. If the blistered area is not kept clean and free from irritation, it may become infected with group A Streptococcus or Staphylococcus bacteria. If the infection is severe, scarring can occur.

Guillain-Barre Syndrome. Guillain-Barre syndrome is caused by inflammation of the nerves and has been associated with a number of viruses, including herpes zoster. The arms and legs become weak, painful, and, sometimes, even paralyzed. The trunk and face may be affected. Symptoms vary from mild to severe enough to require hospitalization. The disorder resolves in a few weeks to months. Other herpes viruses (cytomegalovirus and Epstein-Barr), or bacteria (Campylobacter) may have a stronger association with this syndrome than herpes zoster.

Effects on Face and Ears.

• Ramsay Hunt Syndrome. Ramsay Hunt syndrome occurs when herpes zoster causes facial paralysis and rash on the ear (herpes zoster oticus) or in the mouth. Symptoms include severe ear pain and hearing loss, ringing in the ear, loss of taste, nausea, vomiting, and dizziness. Ramsay Hunt syndrome may also cause a mild inflammation in the brain. The dizziness may last for a few days, or even weeks, but usually resolves. Severity of hearing loss varies from partial to total; however, this too usually always goes away. Facial paralysis, on the other hand, may be permanent.
• Bell's Palsy. Bell's palsy is partial paralysis of the face. There is some indication that this syndrome may suggest a reactivation of herpes zoster, even if no rash appears.

Sometimes, it is difficult to distinguish between Bell's palsy and Ramsay Hunt syndrome, particularly in the early stages. In general, Ramsay Hunt syndrome tends to be more severe than Bell's palsy.

Effects on the Brain. Inflammation of the membrane around the brain (meningitis) or in the brain itself (encephalitis) is a rare complication in people with herpes zoster. The encephalitis is generally mild and resolves in a short period. In rare cases, particularly in patients with impaired immune systems, it can be severe and even life threatening.

Effects in the Urinary Tract. In rare situations, herpes zoster can infect the urinary tract and cause difficulty in urination. The condition is temporary but may require a catheter for patients who have trouble urinating.

Infections in the Eye. If shingles occurs in the face, the eyes are at risk, particularly if the path of the infection follows the side of the nose. If the eyes become involved ( herpes zoster ophthalmicus), a severe infection can occur that is difficult to treat and can threaten vision. AIDS patients may be at particular risk for a chronic infection in the cornea of the eye.

Herpes zoster can also cause a devastating infection in the retina called imminent acute retinal necrosis syndrome. In such cases, visual changes develop within weeks or months after the herpes zoster outbreak has resolved. Although this complication usually follows a herpes outbreak in the face, it can occur after an outbreak in any part of the body. Prompt treatment with acyclovir can often halt its progress, at least in people with healthy immune systems. Either acyclovir or valacyclovir, a similar drug, may prevent other eye complications, such as conjunctivitis (pink eye), inflammation of the cornea, and pain.

Disseminated Herpes Zoster. As with disseminated chickenpox, disseminated herpes zoster, which spreads to other organs, can be serious to life-threatening, particularly if it affects the lungs. People with compromised immune systems are at greatest danger, with risk of 5 - 25%. It is very rare in people with healthy immune systems.

In very rare cases, herpes zoster has been associated with Stevens-Johnson syndrome, an extensive and serious condition in which widespread blisters cover mucous membranes and large areas of the body.

High-Risk Candidates for Complications of Chickenpox, Shingles, or Both

Elderly people. The older the patient, the higher the risk for complications from either chickenpox or shingles. Adults who smoke are at particularly higher risk for pneumonia from chickenpox.

Patients with Serious Illnesses. People with serious illnesses may be at risk for complications of the varicella-zoster virus. Patients with diseases, such as Hodgkin's disease, who receive bone marrow or stem cell transplants are at higher risk for herpes zoster and its complications.

Pregnant Women. Pregnant women who become infected with the varicella-zoster virus, whether in the form of chickenpox or shingles, are at increased risk for serious pneumonia.

• The risk for the infant is lower or higher depending on when the mother became infected.
• Chickenpox in the mother during early pregnancy poses a slightly increased risk for birth defects in the infant.
• The highest risk for birth defects is about 2%, which usually occurs if the mother has chickenpox between the 13th and 20th week. Even in such cases, birth defects may only result in minor skin abnormalities. More serious defects include a smaller than normal head, eye problems, low birth weight, and mental retardation.
• If women develop chickenpox (not shingles) within 5 days before and 2 days after delivery, their newborns are at risk for life-threatening varicella.

Newborns and Infants. Chickenpox in newborns is a life-threatening condition. Although chickenpox can still be very dangerous in older infants, most are protected by antibodies in breast milk from mothers who have had chickenpox. Children under age 1 who develop chickenpox are at higher risk for childhood shingles. All infants should have as little exposure as possible to people with chickenpox.