Eczema vaccinatum

Did You Know?

• In March 2007, a two-year-old boy in Indiana developed eczema vaccinatum over 80 percent of his body surface area after his father was vaccinated for smallpox as part of US Armed Forces protocol.
• Experimental models show that Filaggrin deficiency, common in atopic dermatitis, facilitates systemic vaccinia spread.
• Eczema is also associated with increased complications from other vesiculating viruses such as chickenpox, termed eczema herpeticum.

Symptoms

Serious local or disseminated, umbilicated, vesicular, crusting skin rashes appear on the face, neck, chest, abdomen, upper limbs, and hands. These arise from widespread skin infection in people with previously diagnosed eczema or atopic dermatitis, even if those conditions are not active. Fever, facial and supraglottic edema, malaise, and tender lymphadenopathy accompany the rash. Survivors may develop scarring (pockmarks). The condition can be fatal if severe and left untreated.

Presentation

After exposure to the vaccinia virus, a rash typically appears within 5 to 19 days. Since the vaccine donor’s inoculation spot may have healed normally, doctors should always check for recent household contact with someone vaccinated. The skin shows hundreds to thousands of identical, dimpled bumps or pus-filled lesions on areas affected by eczema, along with fever and swollen lymph nodes. Rarely, the eyes or mouth are involved, but this can lead to breathing trouble or corneal inflammation. The worst cases occur in first-time vaccine recipients and unvaccinated household members.

Diagnosis

Doctors suspect eczema vaccinatum when a patient with eczema develops multiple vaccinia-like sores away from the vaccination site, or after close contact with a recently vaccinated person. Confirmation requires real-time PCR or culture to find orthopoxvirus DNA from a lesion, telling it apart from eczema herpeticum or impetigo. The CDC defines it as a diffuse skin complication; confirmed cases must go to VAERS for a public health response.

Treatment

Eczema vaccinatum requires immediate intensive medical care. Supportive therapy includes antibiotics, fluid replacement, antipyretics, analgesics, and skin healing. Vaccinia immune globulin (VIG) can be very useful, though supplies may be deficient. Severe or progressive illness unresponsive to VIGIV may be treated with antiviral drugs such as Cidofovir or Tecovirimat. Tecovirimat, FDA-approved for smallpox in 2018, offers a targeted inhibitor with fewer renal toxicities than cidofovir and is available under expanded-access protocols for EV.