varicella (chickenpox)

Last edited 07/2021 and last reviewed 02/2023

Chickenpox is a highly infectious, acute contagious disease predominantly of children under 10 years old, though it may occur at any age. It is characterised by fever and a rash, and is caused by varicella zoster virus (1).

The name chickenpox is said to relate to the similarity of the skin lesions to boiled chick-peas.

Around 90% of people who come into contact will develop the disease (1).

Transmission is through

  • direct person to person contact
  • airborne droplet infection
  • through contact with infected articles such as clothing and bedding (1)

Around 90% of adults over the age of 18 years have immunity for VZV in the UK (3). Although not seen in recent years, varicella infections occurs in a seasonal pattern with a peak incidence from March to May (2).

Reactivation of latent VZV will result in shingles (herpes zoster) which is more likely to be seen in adults (2).

A person exposed to shingles may develop Chicken pox but a person exposed to Chicken pox will not develop Shingles (2).

Click here for an example image of this condition

Key points (4):

  • pregnant/immunocompromised/ neonate:
    • seek urgent specialist advice
  • chickenpox:
    • consider aciclovir if:
      • onset of rash <24 hours, and 1 of the following:
        • >14 years of age;
        • severe pain;
        • dense/oral rash;
        • taking steroids;
        • smoker
    • give paracetamol for pain relief

Reference:

Related pages:

clinical features

investigations

differential diagnosis

treatment

complications

chickenpox in certain subgroups

infectivity of some common infections

exclusion from school (guidance re: common infections)

varicella vaccination in children

recurrent episodes ( getting chickenpox twice )

shingles (zoster)

chickenpox (varicella) or shingles (zoster) -post-exposure risk assessment: does the person need PEP (post exposure prophylaxis)?

shingles (zoster) and varicella (chickenpox) and use of NSAIDs