A 24-year-old man presented with a rash. He developed myalgias, fever, headache, and abdominal pain a week earlier. Three days before presentation he developed a pruritic rash that started on his face, arms, and feet. He had no medical problems.
What is the likely diagnosis? See p. 12.
Diagnosis: Chicken Pox
Herpes simplex viruses (HSV) are ubiquitous double-stranded DNA viral pathogens that can cause a wide variety of illnesses. Eight herpes viruses infect humans, and the varicella zoster herpes virus (VZV) serotype causes two distinct clinical syndromes: chickenpox, the primary infection, and shingles, the secondary infection.
Patients with primary VZV have a prodrome of generalized malaise, fever, headache, abdominal pain, fatigue, and chills that may precede the classic chickenpox rash by up to five days. The rash typically begins 10 to 21 days after contact with an infected individual. Classically a maculopapular rash is followed by a cluster of clear vesicular blisters on an erythematous base. The lesions then evolve over three to five days, and can coalesce into larger lesions that progress into pustules and eventually open, creating a shallow ulcer, and then they crust over. The average child develops 250 to 500 small pruritic, fluid-filled blisters on an erythematous base. Often blisters are first seen on the face, torso, and scalp, but can appear on any skin surface including mucous membranes. The rash can be pruritic and painful.
Chickenpox is typically a clinical diagnosis because the rash has characteristic features. If laboratory confirmation is required, direct fluorescent antigen assay (lesion scraping smeared on a slide and stained) or DNA polymerase chain reaction techniques are superior to culture.
Acyclovir can shorten the duration of symptoms, decrease the severity of infection, and reduce the duration of pain (Cochrane Database Sys Rev 2009 Apr 15;:CD006866) if taken within 24–48 hours of symptoms onset, but is usually reserved for patients who are immunocompromised or at risk for severe infection. Acyclovir can reduce the number of days with fever in otherwise healthy children with chickenpox, but its effect on sores and itching is not yet certain. (Cochrane Database Sys Rev 2009 Oct 19;:CD002980.)
Otherwise supportive care is the mainstay of treatment, and can include light clothing to cover areas to avoid night-scratching, skin-soothing oatmeal or cornstarch baths in lukewarm water, skin moisturizer, oral antihistamines, and over-the-counter hydrocortisone creams. Patients with primary VZV infection should not be given aspirin because of its association with Reye's syndrome.
Chickenpox is very contagious. Fluid from the blisters or respiratory droplets are known to transmit disease, and patients are be contagious for one to two days before lesions appear. Patients should keep weeping lesions covered to prevent scratching them because they can become infected or create scars and because those not exposed to or vaccinated against VZV are susceptible. Good hand hygiene is also recommended. Once lesions are completely crusted over, the contagious phase is complete. (JAMA 2011;305:212.) Total healing takes two to four weeks, and residual scarring can occur. Pregnant mothers also can transmit the infection to their neonate.
The FDA approved the live Oka varicella vaccine for administration in children 19–35 months in March 1995. The vaccine comes in a single antigen (Varivax) or a combination measles-mumps-rubella-varicella vaccine (ProQuad). It is currently recommended that the first dose be given when the child is 12–15 months with a booster at age 4 to 6. (www.cdc.gov.) It is recommended that those 13 and older who have not had chickenpox or the vaccine be vaccinated with two doses four to six weeks apart. This is a live attenuated vaccine and not recommended for patients who are pregnant, under 12 months old, or immunocompromised. (MMWR Recomm Rep 2008;57[RR-5]:1.)
A growing body of literature shows the vaccine may be well tolerated in moderately immunocompromised children (Curr Opin Infect Dis 2012;25:135), but more studies are needed in adults. Vaccination is recommended for unvaccinated immunocompetent patients who are varicella naïve three days after exposure (Cochrane Database Sys Rev 2008 Jul 16;:CD001833), and should be considered five days after exposure. (www.cdc.gov.) The vaccine is still contraindicated in immunocompromised patients, according to the Centers for Disease Control and Prevention.
The epidemiology of the disease has changed significantly since the vaccine was introduced, with a decreased incidence as high as 90 percent. (J Infect Dis 2008;197[Suppl 2]:S71.) The rate of hospitalization has decreased to 6.47 per 1000 cases (J Infect Dis 2008;197[Suppl 2]:S120), and only six deaths were reported in 2007 (five were in adults). (www.cdc.gov.)
The most common complication of primary VZV infection is recurrence. The virus migrates after primary infection retrograde on the involved nerve axon to the sensory nerve ganglion where it lays dormant in nerve cells (dorsal root ganglion) until reactivated, causing shingles, or “herpes zoster.” (New Engl J Med 2002;347:340.) The exact pathophysiology and etiology of VZV reactivation is unknown (Lancet Infect Dis 2004;4:26), but an age-related decline in VZV-specific cell-mediated immune responses appears to be important. (JAMA 2009;302:75.) Reactivation results in recurrent infection with subsequent shedding of HSV. Approximately one in 10 patients will develop shingles when the dormant virus re-emerges during a period of stress.
Other complications of primary VZV infection are far less common, occurring in approximately one percent of immunocompetent unvaccinated patients, and include myocarditis, pneumonia, transient arthritis, encephalitis, and hepatitis. Very old and very young patients or those who are immunocompromised are at increased risk of developing these complications. Few vaccinated individuals are reported to get a mild varicella-like syndrome (<3%). Cases are typically milder with only a maculopapular rash and perhaps a few pox that may make it more difficult to diagnose.
This patient had confirmed VZV infection without pneumonia, and supportive measures were recommended.
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