Varicella is a very contagious disease caused by varicella-zoster virus, a DNA virus of the herpes virus family1,2. Following the initial episode of varicella illness, the virus establishes latency in the body’s nerve system, and can be reactivated later in life as herpes zoster which is known as shingles1.
Varicella is very common worldwide and in densely populated metropolitan communities1. Although rates of childhood varicella have been greatly reduced with the implementation of universal childhood immunization programs, a greater number of cases are now occurring in adolescents and adults1. Some data suggest that people from the tropics are less likely to acquire immunity in childhood and therefore have higher rates of susceptibility as adults1.
Symptoms may take 10 to 21 days to appear post infection1. Individuals are most contagious from 1 to 2 days before to shortly after the onset of rash1. The duration of illness is approximately 5 to 7 days and persists until the skin lesions crust over2. Initial symptoms include a slight fever, mild headache, runny nose and general malaise1.
Defining symptoms of varicella1:
Varicella is solely a human disease; the virus can be spread by direct contact with fluid in the lesions or through airborne spread from the respiratory tract1. The attack rate among susceptible contacts in household settings is estimated at 65%-87%1.
Varicella can be prevented through vaccination1,4,5. Most people who get the vaccine will not get chickenpox2. If a vaccinated person does get chickenpox, it is usually mild with fewer red spots2. The vaccine prevents almost all cases of severe disease. The National Advisory Committee on Immunization (NACI) recommends that healthy children 12 months to 12 years of age should receive two doses of varicella-containing vaccine (univalent varicella or MMRV) for primary immunization1,4,5. Different vaccines have different dosing schedules. For further information on the various vaccination options, please speak with your healthcare provider
For further information about varicella vaccine and its use in adolescents, adults and special populations, please refer to the most recent version of the Canadian Immunization Guide1.
People who have or suspect that they have varicella should be reported to the local health authority1. In addition, isolation can mitigate the spread of illness1:
Symptoms of varicella can be alleviated with the following6:
Keeping fingernails trimmed short may help prevent skin infections caused by scratching blisters.
Antiviral medications may be prescribed by the healthcare provider for people with varicella who are more likely to develop serious disease including:
Medical advice is recommended for the onset of chicken pox-like symptoms. For further information regarding chicken pox and immunization, please speak with your healthcare provider.