Infectious Diseases Case of the Month #16

Note--Click here (rather than on image) for close up view of the rash.

A 7 m.o. white male was seen in the emergency room in July 2007 for fever and rash after exposure to a military member recently vaccinated for smallpox.

Five days prior to the development of fever and rash the child and his parents had attended a going away get-together for a soldier-relative due to deploy to Iraq a short time later. At some point during this gathering the child slid down the solidier's uncovered vaccinated arm. As the child did so, he directly contacted the smallpox vaccine pustule and reportedly also licked the site in the process. The serviceman had been vaccinated nine days prior to this incident. When the parents realized what had happened, they immediately called a local emergency room. They were advised to observe the child for fever and rash.

The child had developed a fever of 102 degrees and had become somewhat fussy and less apt to feed. On examination in the emergency room he had a macular to slightly papular rash scattered variously about his body including lesions on his face, neck, chest, abdomen, and extremities (see image at upper left). The skin lesions were generally a millimeter or less in diameter, and there was no oral involvement. The rash was not pustular nor vesicular, and the infant did not appear acutely ill. Laboratory evaluation included WBC 5.4; Hgb could not be determined because of agglutination of RBCs (likely due to the capillary blood draw). Over a 24 hr period of observation the rash became more extensive in its distribution but did not become pustular or vesicular.

The 7 m.o. infant was previously healthy and was up to date on immunizations. He had no known skin conditions. Other family members were not ill, and the child's parents were unaware of exposures to other children ill with chicken pox or other childhood rash illnesses.

Successful smallpox vaccine "takes" follow a stereotypical progression of pustulation and scabbing usually over a period of three weeks. At nine days post-vaccination the pustule would appear similar to those pictured in images at lower left. Smallpox vaccination is performed using live virus. There is risk of transmission of this virus to non-immune direct contacts until the vaccination site has scabbed and the scab fallen off.

       
What was the cause of this child's rash illness?
   
     
Diagnosis: Echovirus 9
   

This child's rash and fever were likely due to Echovirus 9 infection.

This child was seen urgently because of the obvious concern that he might have contracted vaccinia through his direct contact with the vaccination site of the 19 y.o. serviceman. The rash, however, did not become pustular or vesicular as would be typical for vaccinia and the child remained well. By the fourth or fifth day the rash had resolved. A throat culture was positive for Echovirus 9. Varicella IgM serology was negative as were serologies for Human Herpesvirsus 6, the causative agent of Roseola. Primarily because of the short duration of illness and the maculo-papular character of the rash this was thought not to be vaccinia or chicken pox. The child's illness may have been due to Echovirus 9, one of many enteroviruses that can cause childhood exanthems and whose incidence is more common in the summer season. Evaluation was conducted with the aid of the Michigan Dept of Community Health, the CDC, and the U.S. Dept of Defense.

This case raised the specter of contact vaccinia, a sometimes very severe and life-threatening consequence of contact with a smallpox vaccinee. Smallpox vaccination is performed with vaccinia, an orthopox virus related to Variola, the smallpox virus. Persons who acquire vaccinia infection from contact with a vaccinee can have a variety of manifestations of the infection just as can vaccinated individuals. Images at left illustrate some of the potential forms of illness. Localized inoculation (top image) can occur as can generalized vaccinia (2nd image). These infections are generally benign and require no specific therapy. Person with eczema or those who are significantly immunocompromised are at greatest risk of severe, sometimes fatal illness. Illness in these cases occurs in the forms of eczema vaccinatum and progressive vaccinia as illustrated in the lower two images at left.

Routine smallpox vaccination was discontinued in the United States in the early 1970's, and the disease was declared eradicated worldwide in 1980. With the threat of the potential use of this organism as an agent of bioterror, smallpox vaccination has been resumed selectively. Several thousand healthcare workers were vaccinated in a vaccination campaign in 2003, and military members continue to receive vaccination. Several cases of contact vaccinia have occurred in this modern era of smallpox vaccination including one recent case of severe eczema vaccinatum in an infant.

Variola minor and Variola major were strains of the virus that caused smallpox. Variola minor was a less virulent strain that resulted in significantly less mortality in those infected. Since it has been eradicated from nature, it would not have been the cause of illness in the preceding vignette in the absence of its deliberate or accidental reintroduction.


Ref:Smallpox vaccination and adverse reactions guidance for clinicians, MMWR February 21, 2003 / Vol. 52 / No. RR--4.


 

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