Century-old smallpox scabs discovered

Medical Laboratory Observer, Feb, 2004

Century-old smallpox scabs discovered. Scabs from 19th-century smallpox vaccinations were found in a New Mexico university library. Inger Damon, chief of the Centers for Disease Control and Prevention's (CDC's) pox virus group, thinks since the sample is so old, it is "highly unlikely" that the scabs will yield live smallpox, but believes the discovery could shed some light on the development of American smallpox vaccines. Within days of the finding, two FBI agents went to the library in Santa Fe to pick up the scabs. Then on April 3--the same day the FBI received them--the scabs were forwarded on to the CDC in a triple-bagged, overnight mail package. The sample now resides in a freezer at the CDC.

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Susanne Caro, the librarian at the College of Santa Fe's Fogelson Library, found the scabs in an envelope inside an 1888 book on Civil War medicine written by Dr. W.D. Kelly who had done work on childhood vaccinations in the late 1800s. The inscription on the envelope read, "scabs from vaccination of W.B. Yarrington's children," and was signed by Kelly.

Caro contacted George Wunderlich, executive director of the National Museum of Civil War Medicine in Frederick, MD, who notes that during the late 1800s, pus or bits of scabs from smallpox patients with mild cases were implanted in the skins of healthy people to generate a mild illness that bestowed lifetime immunity. The practice, used in the early 18th century, predated the cowpox-based vaccine that later became standard. Cowpox virus was used in inoculations in 1796 by Edward Jenner.

Paul Sledzik, a forensic anthropologist at the Armed Forces Institute of Pathology at Walter Reed, after speaking with Wunderlich, stated, "To be able to look at an untreated specimen from the 19th century using the tools of today is incredible. If you want to look at disease evolution, this would be the perfect opportunity to do that."

According to Damon, "This could lead to a greater evolutionary understanding of the smallpox vaccine we're using in the United States. It all depends on what's in there." Through a series of tests slated for next year, the CDC hopes to develop a genetic portrait of the virus used in the vaccine--likely cowpox.

"These scabs will potentially be the oldest material we'll have looked at in terms of being able to determine any kind of genomic characterization," says Damon.