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Journal of Clinical Microbiology, March 2004, p. 1373-1375, Vol. 42, No. 3
0095-1137/04/$08.00+0 DOI: 10.1128/JCM.42.3.1373-1375.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.
Wadsworth Center,1 Division of Epidemiology, New York State Department of Health, Albany, New York2
Received 22 August 2003/ Returned for modification 27 October 2003/ Accepted 24 November 2003
| ABSTRACT |
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| CASE REPORT |
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Isolated nucleic acid from two lesions was analyzed using real-time PCR (rtPCR) assays provided by the Centers for Disease Control and Prevention Laboratory Response Network (CDC LRN): a vaccinia virus-specific assay, a varicella-zoster virus (VZV)-specific assay, and an endogenous control Escherichia coli 16S ribosomal DNA assay to identify PCR inhibition. The 16S assay detects residual E. coli DNA present in recombinant Taq polymerase. The VZV assay was performed because this virus is the most likely cause of pustular rashes which could be misdiagnosed as smallpox or vaccinia. The vaccinia virus (strain WR) and VZV positive controls were obtained from the Wadsworth Center Viral Culture Collection and were included, in duplicate, for each assay performed. Controls were spiked at a concentration that produced a final cycle threshold (Ct) value of 30 to 33 to serve as a reliable indicator that the rtPCR assay was functional even at low concentrations of virus. The rtPCR was performed using an ABI Prism 7000 Sequence Detection system (Applied Biosystems, Foster City, Calif.) with the following PCR parameters: Taq activation for 8 min at 95°C, denaturation for 15 s at 95°C (45 cycles), and annealing and extension for 30 s at 63°C (45 cycles), with the 9600 emulation option OFF. Data were analyzed using the ABI Prism 7000 SDS software, and the resultant Ct values are reported (Fig. 1B).
VZV genomic sequences were undetectable in lesion fluid, and sample matrices exhibited no inhibition following extraction. Vaccinia virus-specific DNA detected in the lesions supported the clinical diagnosis of GV. The presence of disseminated orthopoxvirus was secondarily confirmed by electron microscopy of material eluted from swabs taken from the base of each lesion. Samples were mounted on 400-mesh copper Formvar grids, stained with 2% phosphotungstic acid, and visualized on a LEO 910 (Carl Zeiss Inc., Thornwood, N.Y.) transmission electron microscope operating at 80 keV. The size and morphology of the particles visualized were definitively characteristic of an orthopoxvirus (Fig. 1C). The final laboratory result was reported in less than 6 h from the receipt of specimens, confirming the usefulness of this algorithm for rapid diagnosis of adverse events following vaccination. Therapy with vaccinia immune globulin or cidofovir was not required, because the lesions resolved within 8 days and the patient showed no additional side effects.
Since its development by Edward Jenner in 1796, the live vaccinia virus vaccine has saved countless lives that would otherwise have been lost to smallpox. The cross protection afforded by the vaccine led to the eradication of smallpox virus from the environment as declared by the World Health Organization on 9 December 1979. This declaration justified the termination of routine vaccination of civilians around the world. Declared stocks of smallpox virus are maintained at two World Health Organization reference laboratories in the United States and the former Soviet Union, but unfortunately, virus cultures may also be possessed by other organizations (3). The perceived smallpox threat was minimal until September 2001, when anthrax was used as a terrorist weapon to kill five people in the United States. The possibility of biological terrorism precipitated a reevaluation of the smallpox threat and prompted the United States and other countries to reinitiate vaccination programs. The live virus vaccine used in the current U.S. vaccination program is the same Wyeth Dryvax preparation that was used in the United States for the eradication effort.
The mortality rates of
0.002% (5, 6) associated with smallpox vaccination were minimal compared to the mortality rate (>30% [3]) associated with variola virus infection when smallpox was endemic. The severe adverse events (SAE) associated with the live virus vaccine were believed to be due to underlying defects in the immune system (progressive vaccinia, vaccinia necrosum, or GV) or dermatologic disorders (eczema vaccinatum or erythema multiforme) (5, 6). Contraindications, including immunosuppression, skin disease, and pregnancy, were not considered during the eradication effort. GV is defined as dissemination of virus to sites distal to the vaccination site. It is differentiated from eczema vaccinatum by the absence of diagnosed eczema or other skin conditions and is considered life-threatening only in cases involving underlying immunodeficiency (2). Although true generalized spread as evidenced by peripheral pustules containing virus is believed to be uncommon (4), recent clinical trials showed that 14.3% of vaccinees exhibited rashes, the majority of which were pustular or vesicular rashes on the chest and back (1).
This is the first reported case of a vaccinia SAE confirmed by using CDC LRN rtPCR methods. The absence of contraindications and the rapid clearance of generalized lesions suggest that vaccinia virus dissemination from an inoculation site is not necessarily dependent on a compromised immune status. The mild clinical presentation of this rash (small, pustular lesions on the chest and back) was similar to that described by Frey et al. (1), who did not diagnose it as GV. This similarity suggests that generalized spread of vaccinia virus from the site of inoculation may be more common than previously thought, and it supports the use of the CDC LRN methods to differentiate GV from postvaccination rashes. This event also provides real-world validation of the CDC LRN system and its implementation in New York State. The evolution of the Laboratory Response Network over the past 2 years has provided a strong foundation for public health infrastructure and will enable public health laboratories to respond rapidly and effectively to emerging infectious diseases and bioterrorism events.
| ACKNOWLEDGMENTS |
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This work was supported by a Public Health Preparedness and Response for Bioterrorism grant from the CDC (Cooperative Agreement U90/CCU216988-0303).
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