|Description:||The glass vial depicted here was labeled “CEM 3831”. Though the meaning of the label is unknown, it was relevant in the context of the epidemiologic plague investigation, which prompted the collection of the fleas inside this vial. Containers like this one need be correctly labeled with waterproof tape, and indelible ink, in order to be accurately tied to a respective investigation.|
Captured fleas should be placed in a 1 dram vial containing 2% saline solution to which one or two drops of Tween 80 (polysorbate) per liter has been added. The Tween 80 is a surfactant that breaks the surface tension of the water, allowing the fleas to sink in the saline and drown. Although the vector fleas die, Plague organisms will remain viable in the saline solution for a number of days, especially if kept refrigerated.