Varicella Virus, the Old and the New

I want to reawaken awareness of a disappearing but highly contagious infectious disease — varicella. Thanks to immunizations for the wild-type varicella virus and shingles, or herpes zoster, younger health care providers are less aware of the appearance and clinical presentations of this viral infection.

Presentations of this viral disease have markedly declined and presentations are often atypical since the advent of immunizations for varicella in 1995. This DNA virus within the herpes virus family is generally a mild childhood disease but can wreak physical havoc in adults, especially pregnant women. Immunosuppressed adults and children can also experience life-threatening complications.

Thankfully, the rate of infection, hospitalizations, and mortality have all declined. Nevertheless, we should not let our guard down. The disease is still out there and presents to the emergency department in less obvious or clear-cut presentations, ready to trip up the unsuspecting clinician.

Most recently, a 6-year-old boy who had been vaccinated presented to our pediatric emergency department with the virus. I treated a febrile girl on chemotherapy for acute lymphocytic leukemia during the same shift, and one of the nurses working with us was pregnant. Thankfully, the infectious varicella patient did not come into contact with either of them. Nevertheless, the story could have been very different.

Chickenpox is highly contagious, and secondary attack rates in households are as high as 90 percent. (MMWR Recomm Rep 1996;45[RR-11]:1.) Transmission is by contact with aerosolized droplets from nasopharyngeal secretions or by direct contact with vesicle fluid from skin lesions.

Again, the problem is that we don’t see as many disease presentations of this virus anymore, and varicella has dropped way down on our differential for rashes presenting to the ED. Our previous hyper-awareness of the disease has lessened, and immediate infectious disease precautions may not be as rapidly activated.

The typical chickenpox presentation is a generalized pruritic rash in a febrile child that begins as macules on the head, chest, and back after a short prodrome. The rash then spreads to the rest of the body in successive crops while transforming in appearance from macules to papules and vesicular lesions that eventually crust over. New vesicle formation usually stops within four days, and most lesions are fully crusted by day six.

Breakthrough varicella infections are defined as an infection by the wild virus that occurs at least 42 days after vaccination. The patient is typically afebrile or will have only a low-grade temperature, the number of skin lesions present are usually less than 50, and the duration of the illness is usually shorter. Consequently, the clinical diagnostic features are mild, and the diagnosis can be difficult to confirm on clinical presentation alone. Laboratory testing is becoming increasingly necessary. Unfortunately, this disease presentation remains contagious, as does herpes zoster or disseminated disease in immunosuppressed patients.

Treatment and prevention recommendations can be found in several excellent sources online:

Two rare presentations of the varicella virus are presented: disseminated varicella in a vaccinated 6-year-old with breakthrough chickenpox and an HIV patient with herpes zoster. Both patients had clinical presentations different from the now-uncommon garden-variety varicella.

Watch a video of disseminated varicella in an HIV patient.​

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Watch a second video of breakthrough chickenpox in a 6-year-old boy who was vaccinated.


Watch a third video showing several patients with typical varicella presentations. These children were filmed during a recent medical mission trip to Haiti where vaccination for varicella is neither mandatory nor widespread.


Tags: varicella, herpes zoster, chickenpox, pediatrics, pruritic rash, HIV, vaccination, Haiti, emergency department, emergency medicine
Published: 2/1/2017 4:12:00 PM

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