Derm Dx: Crops of small, red, itchy spots


  • Chickenpox_Man

  • Chickenpox_Tongue

  • Chickenpox_Back

  • Two-dose vaccination program cuts varicella incidence


Clinical Description

A rash that often appears in crops that consist of small, red, itchy spots. These become fluid-filled blisters about 5- to 10-mm in diameter within a few hours and scab over the course of a few days. The blisters can occur wherever there is skin, including the mouth, throat, and vagina. Other symptoms include headache, mild fever, and general malaise. What’s your diagnosis?

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Varicella, or chickenpox, is a common illness that occurs mostly among children aged younger than 12 years and is caused by infection with varicella-zoster virus; however, adults who have never been infected and have not been vaccinated can develop chickenpox,...

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Varicella, or chickenpox, is a common illness that occurs mostly among children aged younger than 12 years and is caused by infection with varicella-zoster virus; however, adults who have never been infected and have not been vaccinated can develop chickenpox, too.

Two vaccines are currently available in the United States to protect against chickenpox: a single-antigen varicella vaccine (Varivax, Merk), licensed in 1995, and a combination measles, mumps, rubella, and varicella vaccine (MMRV, Proquad, Merck), licensed in 2005.

Before the introduction of varicella vaccine, chickenpox was endemic in the United States with nearly everyone experiencing an infection by adulthood. Since vaccine implementation varicella incidence has declined among all age groups, with the greatest decline among children aged 1 to 4 years, according to the CDC.

Clinical presentation

People with chickenpox present with a highly contagious pruritic rash that begins on the abdomen, face, or back and then spreads to the rest of the body, including the scalp, mouth, nose, ears, and genitals. The rash consists of 250-500 lesions that progress rapidly from macules and papules to vesicles, pustules, and crusts, and is often accompanied by influenza-like symptoms, including low-grade fever and malaise. Some children may experience such symptoms as fever, abdominal pain, sore throat, headache, or a vague sick feeling a day or two before the rash appears.

People with chickenpox are contagious two days before rash onset until all the blisters have crusted over (usually four to seven days), and children with the virus should be kept out of school for one week to prevent spread of the disease. Chickenpox is a self-limiting infection that resolves on it’s own within two weeks of onset.

Although most people only experience one episode of chickenpox, varicella-zoster virus lies dormant in the body and may cause herpes zoster, or shingles, later in life.

Rapid diagnostic tests, including polymerase chain reaction and direct fluorescent antibody, can be used to confirm varicella-zoster virus in vesicular fluid or scabs or isolated from vesicle scrapings during the first three to four days of the rash.


Since a virus causes chickenpox, prescribing antibiotics is not necessary unless the blisters become infected. Acetaminophen may also be used to ease prodromal symptoms. Calamine lotion, oatmeal baths, and antihistamines can help relieve itchiness.


The CDC’s Advisory Committee on Immunization Practices recommends that all children age 12 months to 12 years be vaccinated against varicella accordingly:

  • First dose: Children should receive one dose of MMRV at age 12-15 months. If a child is not vaccinated according to schedule, he or she may receive the first dose through age 12 years. Due to concerns about increased risk for febrile seizures among young children administered MMRV, clinicians may administer either single-antigen varicella vaccine or MMRV to children age 12-47 months; however, the CDC expresses a preference for MMRV. 
  • Second dose: Routine recommendations state that children aged 4 to 6 years should receive a second dose of MMRV. Clinicians may administer the second dose of MMRV at younger ages provided that three or more months have passed since the first dose was administered.
  • People aged 13 years and older who have never had chickenpox or received the vaccine should be vaccinated with at least two doses at least 28 days apart.

Clinicians can review contraindications and other MMRV precautions online, here.

Before the single-antigen varicella vaccine was licensed in 1995, the CDC estimates that 11,000 people were hospitalized and 100 people died each year from chickenpox. Varicella vaccine prevented more than 50,000 chickenpox-related hospitalizations from 2000 to 2006 data published in the Jan. 2011 issue of Pediatrics indicated.

The CDC notes that breakthrough episodes of chickenpox may occur in vaccinated individuals because varicella vaccine is 70% to 90% effective. These cases are generally more mild, with fewer lesions (<50), shorter duration of rash, and lower fever. Although chickenpox in vaccinated individuals is less severe, it is still contagious and appropriate isolation precautions remain necessary.

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