Russia plague did not escape from test tube, says dead scientist's mother

The mother of a Russian scientist who died in a suspected plague leak has challenged reports that her daughter was infected after breaking a test tube containing plague bacteria.
Darya Shipilova, a 28-year-old laboratory technician at the Siberian anti-plague research institute in Irkutsk, died early on Oct 2 after being taken to hospital in the nearby town of Shelekhov.