A Laboratory Test for Diagnosis of Smallpox

Abstract

The elementary bodies of variola are larger than those of varicella. Skin scrapings from 77 of 80 cases of smallpox ranging from mild to fatal hemor-rhagic variola were positive to the film test (Paschen). The bodies could be easily demonstrated during the papular and vesicular stages of the illness but tended to disappear upon pustulation. In 32 cases of early smallpox the results were positive on the first day but were difficult to diagnose clinically. There were no false positives. The elementary bodies are too small, too sparse, and stained too poorly for the test to be used for chickenpox.