By the time rash, fever, swollen glands, and other symptoms of chickenpox (varicella) begin to appear, the virus will already have been in a person’s body for a week or more.
According to the Centers for Disease Control and Prevention (CDC), the typical incubation period for the varicella virus—the amount of time between when someone is exposed to it and when symptoms begin to show up—averages 14 days, with a range of 10 to 21 days.
A person is considered contagious one to two days before a rash appears until that rash completely crusts over.
Frequent Symptoms
Otherwise healthy people who become sick after being exposed to varicella will develop a cluster of symptoms that are typical of any viral infection in addition to the telltale chickenpox rash. In some people, particularly adults, the non-rash symptoms will appear before the rash does. In kids, the rash is often the first sign of chickenpox.
Non-Rash Symptoms
Most of these symptoms last for a day or two and then disappear as the rash appears. They include:
- Fever (usually mild, around 102 degrees, although it can go as high as 105 degrees)
- Malaise
- Headache
- Loss of appetite
- Mild abdominal pain
- Swollen glands
Remember that a person infected with the varicella virus can be contagious during the couple of days they have these pre-rash, non-specific symptoms.
Chickenpox Rash
The chickenpox rash usually appears first on the torso, scalp, and face, and then spreads to the arms and legs. The rash also can cause lesions on mucous membranes in the eyes, mouth, and vagina (but this isn’t common).
Each chickenpox lesion starts as a 2- to 4-millimeter red papule with an irregular outline, upon which a thin-walled, clear vesicle filled with a highly-contagious fluid develops. The vesicle often is described as looking like a “dew drop.” After eight to 12 hours, the fluid in the vesicle becomes cloudy and the vesicle breaks, leaving behind a crust.
Once a lesion has crusted over it’s no longer considered contagious. The crust usually falls off after about seven days. However, as old lesions crust over and fall away, new ones continue to form, and so it’s typical to have lesions in different stages all at one time. Until all lesions have crusted over and no new ones have formed, a person is considered contagious.
If you or your child come down with chickenpox, you’ll need to stay home from school, work, and other activities to avoid spreading the virus, even if you’re feeling fine otherwise.
The chickenpox rash is extremely itchy, but it’s important not to scratch. When lesions or crusts are scratched off or become infected from contact with dirt under fingernails, unsightly scars can form. For that reason, dealing with the itch is a key part of chickenpox treatment.
The number of chickenpox lesions a person gets varies. The typical range is 100 to 300 lesions. Adults and older kids usually develop more lesions than young children. People who have previously traumatized skin, such as from a sunburn or eczema, may develop a more extensive rash than others.
Rare Symptoms
On rare occasions, children who have been partially vaccinated (had one dose of the varicella vaccine) or even fully vaccinated (have had both doses) come down with chickenpox anyway.
Kids with so-called “breakthrough chickenpox” are less contagious than those who haven’t been vaccinated.
Their symptoms are milder, too—so mild in some cases that breakthrough chickenpox can be misdiagnosed as bug bites or other childhood rashes. The symptoms of breakthrough chickenpox include:
- Fewer than 50 or so lesions
- Few or no vesicles (which is why they aren’t as contagious)
- Low or no fever
- Quick recovery (within three to five days)
Complications
For people who are in good health in general, chickenpox isn’t likely to lead to any serious complications. However, around 14,000 people are hospitalized in the United States each year as a result of the disease. For about 100 of them, it will be fatal.
As many as a third of people who get chickenpox as adults are at risk of serious complications, especially seniors and those with compromised immune systems.
Bacterial Infection
The most common complication of varicella is a secondary bacterial infection of the chickenpox lesions typically caused by Staphylococcus aureus or Streptococcus pyogenes, resulting in skin infections such as impetigo, furunculosis, cellulitis, and erysipelas, as well as an infection of lymph nodes known as lymphadenitis.
These infections are mostly superficial and easily treated with antibiotics. However, there is a risk that the bacteria can spread into the bloodstream, leading to a condition called bacteremia. People with bacteremia are at risk of bacterial pneumonia as well as other potentially serious infections, including meningitis, arthritis, osteomyelitis, and sepsis.
Neurologic Complications
The second most common set of complications of chickenpox involves the nervous system. One of the more serious neurological disorders associated with chickenpox is a childhood condition called acute cerebellar ataxia. Symptoms include fever, irritability that gets worse over time, difficulty walking, and speech impairment that can persist for days or even weeks. Fortunately, these symptoms usually resolve on their own.
Another potential neurological complication of chickenpox is varicella meningoencephalitis, an infection that causes the membranes that surround and protect structures in the nervous system to become swollen and inflamed.
Symptoms can include a headache, sensitivity to light, neck stiffness and pain, delirium, and seizures. The people most at risk for developing meningoencephalitis after being infected with the varicella virus are those who have a compromised immune system, such as patients in a late stage of infection with human immunodeficiency virus (HIV).
Respiratory Complications
Varicella pneumonia is the leading cause of varicella-related illness and death in adults. The disease develops when the virus travels to the lungs via the bloodstream, where it causes infection. Approximately one in every 400 adults who come down with chickenpox will be hospitalized as a result of this illness.
The risk factors for varicella pneumonia include:
- Getting chickenpox at an older age
- Rash with a large number of lesions
- A compromised immune system
- Pregnancy (especially in the third trimester)
- Smoking
- Chronic obstructive pulmonary disease (COPD)
Liver Complications
A common complication of chickenpox is transient hepatitis, a temporary inflammation of the liver that usually doesn’t cause symptoms and tends to get better without treatment.
According to the Mayo Clinic, some children and teens recovering from a viral infection—particularly chickenpox or flu—are at risk of developing Reye’s syndrome, a rare condition that causes swelling of the liver and brain. Reye’s syndrome has also been linked to aspirin, so even though aspirin is approved for kids older than 2, it’s best not to give this drug to them to treat symptoms of chickenpox (or other viral infections).
Shingles
After a person is infected with chickenpox, the virus is not completely eliminated from the body. Instead, it travels to points in the nervous system called ganglia, where branches of nerves come together, remaining inactive and latent.
Certain triggers can force the dormant virus to suddenly become active again, often decades after the initial infection. When this happens, the virus will travel back down the nerve to the skin, causing painful, burning skin blisters along the nerve branch—a condition called shingles, or herpes zoster. Shingles most often affect adults over 50.
When to See a Doctor
Chickenpox is such an easily identifiable illness you often can get a diagnosis from a doctor over the phone. And like any viral infection, it usually gets better on its own.
However, if while you have chickenpox you develop certain symptoms that indicate you might have a secondary infection or other complication, you should call a doctor for an appointment. These include:
- Blisters that become very red and tender; feel warm; become bigger, open sores; and drain pus
- A high fever that persists for more than a few days
- Swollen glands in the neck that are tender to the touch
- Rash that spreads to one or both eyes
- An inability to drink
- Dehydration
- Problems breathing or a constant cough, which could be signs of varicella pneumonia
- A severe headache, sensitivity to light, unusual sleepiness, confusion, or constant vomiting, which together could indicate brain inflammation
These symptoms are cause for concern in kids and adults. If you have a small child with chickenpox who cries constantly and is inconsolable, that’s reason to check in with the pediatrician as well.
Chicken Pox Doctor Discussion Guide
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