By K.R.CALLAWAY A 28-year-old worker at a research laboratory in Siberia recently died of pneumonia. The facility studies plague, among other pathogens, raising fears that she had been exposed at the laboratory. But Russian health officials have not linked the death of the worker, Darya Shipilova, to infection with Yersinia pestis, the bacterium that causes plague. And despite early reports that dozens had been quarantined near the research facility, health officials said that there was no…
