Image of Rickettsia rickettsii

Description:

This photomicrograph of a Gimenez-stained yolk sac smear revealed the presence of Rickettsia rickettsii bacteria, which are the cause of Rocky Mountain spotted fever (RMSF). These bacteria range in size from 0.2 x 0.5 micrometers to 0.3 x 2.0 micrometers. They are difficult to see in tissues by using routine histologic stains, and generally require the use of special staining methods, such as the Gimenez stain used in this case.
Created: 1974