052 – Chickenpox

Varicella is commonly known as chickenpox. It is a self-limiting, infectious viral disease caused by the varicella-zoster virus. Transmission occurs via respiratory droplets or direct contact with the lesions.

Varicella-zoster virus, a member of the herpesvirus group, is an acute, serious viral infection when it occurs in adults. In adults, a 2–3 day prodrome of fever, chills, irritability, headache, and myalgias may occur over a 5–11 day period; however, skin lesions are usually the initial manifestation of the disease.

Once the cutaneous eruption develops, pruritus is intense. Fever is variable, usually less than 38.9°C (102°F), but can be anywhere from normal to 40.6°C (105°F) in severe cases.

The most common complication is secondary infection of lesions with staphylococcus or B-hemolytic strep. The streptococcal infection can progress to necrotizing fasciitis. Varicella pneumonia is more common in adults and can lead to ARDS (adult respiratory distress syndrome).

Less common complications include the following: purpura fulminans and thrombocytopenia with protein S deficiency, orchitis, hepatitis, uveitis, arthritis, myocarditis, nephritis, macular atrophy, GI bleeding, bacterial pneumonia, protein-losing enteropathy, and Reye's syndrome. CNS complications occur rarely. These include aseptic meningitis, dystonia, myelitis, cerebellar ataxia, Guillain-Barré, and encephalitis. The cerebellar form of encephalitis has a high mortality rate in adults.

One varicella episode usually confers lifelong immunity, although reinfections have been documented. Patients are considered contagious for 2–5 days before the onset of cutaneous lesions and for 6 days after the last crop has appeared. Approximately 100 deaths per year in the US are attributed to acute varicella. The highest incidence is from March to May.

An early erythematous, macular eruption that rapidly becomes papular and then vesicular with a surrounding halo of erythema. The initial macular eruption usually begins on the trunk or scalp, and the central portion of the body has the most numerous lesions. Mucous membranes, palms, and soles can be involved with a few lesions. More disseminated involvement can be seen in adults.

The vesicles are usually discrete, unlike the clustered vesicles in herpes simplex virus (HSV) or in herpes zoster (VZV). Vesicles become cloudy and then crust, with healing completed within 1–3 weeks. Simultaneous appearance of lesions in different stages of evolution is characteristic. Occasionally, a scarlatiniform rash appears just prior to or concomitant to the initial macular eruption. Petechiae and purpura have been reported.

The vesicle is classically described as a dewdrop on a rose petal. The vesicle is thin-walled and easily broken.

Drug eruption
Miliaria crystallina
Eczema herpeticum
Disseminated herpes simplex virus (HSV)
Hand-foot-and-mouth disease
Impetigo
Insect bites
Vesicular viral exanthem (Coxsackie, echo)
Pityriasis lichenoides et varioliformis acuta (PLEVA)
Rickettsialpox
Variola (smallpox) – All lesions at the same stage; favors extremities. Note: this disease has been eradicated; therefore, it would only be diagnosed in the event of a bioterrorist act.

Immunofluorescence directly or with cultured material is more sensitive and specific than Tzanck, though the Tzanck will give more immediate results. Tzanck smears may be positive in 100% of cases, but false positives are a problem. PCR can be used to diagnose varicella-zoster virus in CSF.

The pruritus can lead to atrophic scars. If pruritus is intense, systemic antipruritics (eg, Atarax) are more effective than the traditional calamine lotion.

Note: The CDC Advisory Committee on Immunization Practices recommends that all health care workers ensure that they are immune to varicella because nosocomial transmission of varicella is well-recognized. If susceptible persons must enter the room of a patient known or suspected to have varicella, they should wear respiratory protection (N95 respirator). Persons immune to varicella need not wear respiratory protection.

Precautions: Standard and Airborne (Isolate patient in a negative pressure room, wear respiratory protection [N95 mask], and limit patient transport.)

In the US, varicella morbidity and mortality are reportable for many states. Check individual state reporting criteria for more information.

Acyclovir and related compounds can lessen the severity of acute infection. Varicella vaccine imparts protective antibody formation in 96% of patients immunized.

• Acyclovir 800 mg 5 times daily for 7 days
• Famciclovir 500 mg 3 times daily for 7 days
• Valacyclovir 500 mg – 2 caplets 3 times daily for 7 days

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Appearance
Patient Appears Ill
Patient Appears Systemically Ill - Toxic

Distribution
Bilateral Chest
Lower Lobes
Perihilar
Primarily Truncal
Scattered Few
Widespread

Laboratory
Hypoxemia
Thrombocytopenia
Tzanck Smear Shows Multinucleated Giant Cells

Lesion
Excoriated
Ground Glass Opacity
Hilar Lymphadenopathy
Ill-Defined Nodules/Masses
Patchy Consolidation
Tiny Vesicle
Umbilicated Vesicle

Occupations
Health Care Worker (Medical)
Military

Signs and Symptoms
Anorexia (Loss of Appetite)
Chest Pain
Cough
Dyspnea (Shortness of Breath, SOB)
Fever (Febrile)
Headache
Hemoptysis (Coughing Blood)
Lung Exam - Tachypnea
Malaise
Myalgia (Muscle Pain)
Non-Productive Cough
Pleuritic Chest Pain
Pruritus (Itching)
Sore Throat

Social History
Middle/High School (6-12)

Temporal
Developed Acutely Over Days to Weeks
Developed Rapidly in Minutes or Hours

Medical History
Immunosuppression/Immunocompromised
Leukemia NOS
Lymphoma
Malignancy NOS
Pregnancy NOS