Chicken Pox

Chickenpox - symptoms, treatment, vaccination

 Chickenpox is a common infectious disease that 90% of New Zealand children will contract before adolescence. Symptoms include fatigue, mild fever and loss of appetite, followed by a red rash and itchy blisters. Treatment will focus on reducing fever and itching. A chickenpox vaccine will be fully funded for all New Zealand children from mid-2017.

General information

Chickenpox (varicella) is a highly infectious disease that is common in childhood. Chickenpox is usually a mild, self-limiting disease in healthy children but it can be severe if contracted by babies or immune-suppressed children or adults. 

Chickenpox is caused by infection with the varicella zoster virus, a member of the herpes family of viruses. 

The virus is spread in droplets of saliva through the air or by direct contact with the fluid from the blisters of the infected person. Coughing and sneezing are the most common modes of transmission, particularly in children. The peak incidence occurs in the five to nine-year-old age group but with increased use of early childhood centres, a greater proportion of infections may now be occurring in pre-school-aged children. Chickenpox is most common during winter/spring. 

One bout of chickenpox gives lifelong immunity from contracting the disease again. However, the virus remains in the body for life and can be reactivated as shingles (herpes zoster). Shingles can occur at any age but is most common in adults over 60 years of age.

Signs and symptoms

Initial symptoms of chickenpox include fatigue, a mild fever, lack of appetite, and a feeling of being generally unwell. This is quickly followed (usually within 24 hours) by the development of a red rash, which usually appears on the chest and/or back first, later spreading to the face, scalp, arms, and legs. 

Twelve to 48 hours later the rash develops into small red spots. These then turn into yellow fluid-filled blisters, which burst and dry up 3–4 days after they appear. There may be several crops of spots occurring over 4–5 days. The spots cause itching, which may be severe. They may occur all over the body, including the mouth and genital area. Some people may have only a few spots whereas others will have hundreds. 

Symptoms start appearing 10 to 21 days after exposure to the virus. Full recovery from chickenpox usually takes 7–10 days after the symptoms first appear.

Diagnosis

Diagnosis of chickenpox is usually based on symptoms, in particular the presence of its characteristic itchy red rash and different types of lesions being present at the same time. For a diagnosis of chickenpox see a doctor or practice nurse. Chickenpox can be confirmed by laboratory tests, including blood tests or a culture of lesion samples. 

Consult a doctor immediately if the person seems very sick, confused or difficult to waken, or if they have trouble walking or have a stiff neck. Also consult a doctor if the blisters become infected or if there are spots in the eyes, ears or mouth.

Treatment

People with chickenpox should remain at home until they are no longer infectious. Supportive treatment includes:

• Rest
• Pain relief such as paracetamol to relieve fever. Aspirin should not be given, as this has been associated with Reye’s disease (a rare disorder affecting the liver and brain) in children with chickenpox
• Itching can be treated with lotions such as calamine available from a pharmacy.
• Tepid baths with ½ cup of sodium bicarbonate or solutions such as Pinetarsol added can also be helpful in relieving itching
• Because the mouth and throat can be affected, offer soft food and cool drinks. Avoid salty foods and citrus fruits
• To prevent infection of the sores, trim children’s fingernails short and wash hands frequently with antibacterial soap. Discourage scratching as much as possible
• Dress children in light, loose fitting clothing or pyjamas. Overheating and friction from clothing can worsen itching
• Antiviral medications (eg: acyclovir) may be prescribed for some people.

Complications

Although chickenpox is usually a mild and self-limiting disease, complications potentially requiring hospitalisation or leading to death can occur. 

Bacterial infection of the skin, which may need to be treated with an antibiotic, is the most common complication of chickenpox. Serious complications include pneumonia, septicaemia (blood stream infection), and rarely encephalitis (swelling of the brain) and death. 

Chickenpox can cause foetal abnormalities if a non-immune woman contracts the disease between weeks 8 and 20 of pregnancy. Additionally, there is a risk of serious disease in the new-born baby if the mother contracts chickenpox between the fifth day before delivery and the second day after the baby is born. 

Children with chickenpox should therefore be kept away from pregnant women and new-born babies until they are no longer infectious. Pregnant women who have not had chickenpox should see their doctor for control measures if they are exposed to the disease. 

Immune-compromised people – for example those who are HIV positive, organ-transplant recipients, and children with leukaemia – are also susceptible to serious illness as a result of varicella virus infection.

Prevention / vaccination

A person with chickenpox is infectious from 2 days before the rash first appears until after the final crop of blisters have formed scabs, approximately 7–10 days later. The nature of the infectious period makes it very difficult to prevent the disease from spreading. Nonetheless, children should stay away from day care or school, and public places, while they are infectious. Adults with chickenpox who work with children should also stay home. 

The chickenpox (varicella) vaccine is the best way to prevent chickenpox. 

A vaccine against the varicella virus is available for infants from nine months of age, children, and adults. Vaccination may prevent or reduce the severity of chickenpox if it is given within 3–5 days of exposure to someone with the disease. 

The varicella vaccine is available from GPs. It is recommended and funded for certain high risk groups, and is available at a cost to other patients. From 1st July 2017, the varicella vaccine will be funded for all children as part of the New Zealand Ministry of Health’s childhood immunisation schedule.

Further information and support

For more information on chickenpox vaccination, please see your GP or practice nurse, or contact: 

Immunisation Advisory Centre (IMAC) 
Freephone: 0800 IMMUNE (0800 466 863) 
Website: www.immune.org.nz For more information about chickenpox, see your GP or practice nurse, or contact: 

Plunketline 
Freephone: 0800 933 922 
Website: www.plunket.org.nz 

Healthline 
Freephone: 0800 611 116 
Website: www.healthline.govt.nz

References

Jones N. Pharmac confirms chickenpox vaccine for all kids (Web Page). New Zealand Herald (28 July 2016). Auckland: NZME Publishing Ltd. http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11683060 [Accessed: 27/07/16] 
KidsHealth (2014). Chickenpox (Web Page). Auckland: Paediatric Society of New Zealand and Starship Foundation. www.kidshealth.org.nz/chickenpox [Accessed: 27/07/16] 
Mayo Clinic (2016). Chickenpox (Web Page). Rochester: Mayo Foundation for Medical Education and Research. http://www.mayoclinic.org/diseases-conditions/chickenpox/home/ovc-20191271 [Accessed: 27/07/16] 
Ministry of Health (2014). Varicella (chickenpox). Immunisation Handbook 2014 (2nd Edition). Wellington: Ministry of Health. http://www.health.govt.nz/publication/immunisation-handbook-2014-2nd-edn [Accessed: 28/07/16] 
DermNet NZ (2016). Chickenpox (varicella) [Web Page]. Hamilton: DermNet New Zealand Trust. www.dermnet.org.nz/viral/varicella.html [Accessed: 27/07/16] 
 Last Reviewed - July 2016