Chickenpox is an infectious disease caused by the varicella-zoster virus which results in a blister-like rash, itching, tiredness and fever.
Chickenpox is highly infectious and spreads from person to person by direct contact or through the air from an infected person’s coughing or sneezing. A persons with chickenpox is contagious 1-2 days before the rash appears and until all blisters have formed scabs. It takes from 10-21 days after contact with an infected person for someone to develop chickenpox.
In children, chickenpox most commonly causes an illness that lasts about 5-10 days. Children usually miss 5 or 6 days of school or childcare due to their chickenpox. About half of all children with chickenpox visit a health care provider due to symptoms of their illness such as high fever, severe itching, an uncomfortable rash, dehydration or headache. In addition, about 1 child in 10 has a complication from chickenpox serious enough to visit a health care provider including infected skin lesions, other infections, dehydration from vomiting or diarrhea, exacerbation of asthma or more serious complications such as pneumonia.
Certain groups of persons are more likely to have more serious illness with complications. These include adults, infants, adolescents and people with weak immune systems from either illnesses or from medications such a long-term steroids.
Chickenpox has a characteristic itchy rash that often starts on the trunk and face with pink spots and tiny fluid-filled blisters (“pox”) that then dry and become scabs in 4 to 5 days.
The rash may be the first sign of illness and sometimes occurs with fever and general fatigue.
An infected person may have anywhere from only a few pox to more than 500 (average 300-400) pox on their body during the illness.
Chickenpox can sometimes have severe complications such as bacterial skin infections and pneumonia.
Some children who have been vaccinated against chickenpox can get a mild case of chickenpox with a small number of “spots” that may not go on to blister and crust.
Chickenpox is typically diagnosed by the symptoms and the characteristic appearance of the rash.
Occasionally a healthcare provider will use laboratory tests for chickenpox if the diagnosis is unclear or if the illness is severe.
Scratching the blisters may cause them to become infected. Therefore, keep fingernails trimmed short. Calamine lotion and Aveeno (oatmeal) baths may help relieve some of the itching. Do not use aspirin or aspirin-containing products to relieve your child's fever. The use of aspirin has been associated with development of Reye syndrome (a severe disease affecting all organs, but most seriously affecting the liver and brain, that may cause death). Use non aspirin medications such as acetaminophen (commonly known as Tylenol®).
Your health care provider will advise you on options for treatment. Acyclovir (a medicine that works against herpes viruses) is recommended for persons who are more likely to develop serious disease including persons with chronic skin or lung disease, otherwise healthy individuals 13 years of age or older, and those persons receiving steroid therapy. In order for acyclovir to be effective it must be administered within 24 hours of the onset of the chickenpox rash. Persons with weakened immune systems from disease or medication should contact their doctor immediately if they are exposed to or develop chickenpox. If you are pregnant and are either exposed to, or develop chickenpox, you should immediately discuss prevention and treatment options with your doctor.
If a fever lasts longer than 4 days or rises above 102 ºF, call your health care provider. Also take note of areas of the rash or any part of your body which become very red, warm, tender, or is leaking pus (thick, discolored fluid) as this may mean there is a bacterial infection. Call your doctor immediately if the individual with chickenpox seems extremely ill, is difficult to wake up or is confused, has difficulty walking, has a stiff neck, is vomiting repeatedly, has difficulty breathing, or has a severe cough.
Varicella zoster immune globulin (VZIG) can prevent or modify disease after exposure (coming into close contact with a case). However because it is costly and only provides temporary protection, VZIG is only recommended for persons at high risk of developing severe disease. Such persons are not eligible to receive chickenpox vaccine. They include:
- Newborns whose mothers have chickenpox 5 days prior to 2 days after delivery;
- Children with leukemia or lymphoma who have not been vaccinated;
- Persons with cellular immunodeficiencies or other immune problems;
- Persons receiving drugs, including steroids, that suppress the immune system; and,
- Pregnant women.
VZIG should be administered as soon as possible, but no later than 96 hours after exposure to chickenpox. If you have had a varicella exposure and you fit into one of these groups, contact your doctor.
Prevention / Risk Factors
The Center for Disease Control and Prevention’s (CDC) Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians recommend that all children be routinely vaccinated at 12 to 18 months of age, and that all children receive the vaccine before their 13th birthday if they have not had chickenpox.
The ACIP also recommends that children 13 years and older and adults who do not have evidence of prior immunity routinely receive 2 doses of vaccine 4 to 8 weeks apart.
During a chickenpox outbreak, people who have received 1 dose of varicella vaccine should receive a second dose. The doses should be at least 3 months apart for people 12 months to 12 years, and at least 4 weeks apart for people over 13 years.
The vaccine occasionally causes mild side effects including fever and a mild rash that can occur 5 to 26 days after immunization.
You don’t need the vaccine if you have already had chickenpox. If you are not sure whether you have had chickenpox, talk to your healthcare provider about getting a blood test.
Varicella vaccine is highly effective at preventing chickenpox, especially severe cases of the disease, and its complications.