Laboratory-acquired vaccinia infection.

Background: Complications following vaccination with vaccinia virus have been well described but are not commonly observed. The use of vaccinia as a tool in molecular biology, in the development of therapeutics, and the anticipated increase of vaccinations in the general population due to the threat of bioterrorism have created a renewed awareness of the post-vaccination complications and the consequent need for clinical and laboratory diagnosis.

Objectives: To report the clinical presentation and subsequent diagnosis of generalized vaccinia that resulted from a laboratory accident in an unvaccinated subject.

Study Design: The patient was seen by a local infectious disease's specialist and evaluated clinically and with laboratory support relative to a differential diagnosis.

Results: Careful assessment of the patient's history, an evaluation of the workplace, and the elimination of likely microbial etiologies led to the diagnosis of generalized vaccinia. Laboratory confirmation was obtained by use of electron microscopy (EM) to observe poxvirus particles in infected cell cultures.

Conclusions: Exposure to vaccinia virus should raise the index of suspicion for patients with skin lesions. Rapid diagnosis may be accomplished by direct examination of lesion material by EM. The virus also readily replicates in commonly available cell cultures and in the absence of immune reagents, typical poxvirus particles may be observed in the infected cells by EM.