Rickettsia prowazekii causes epidemic typhus. It is spread by lice. Brill-Zinsser disease is a mild form of epidemic typhus. It occurs when the bacteria re-activates in a person who was previously infected.It is more common in the elderly.t is spread by lice. Brill-Zinsser disease is a mild form of epidemic typhus. It occurs when the bacteria re-activates in a person who was previously infected. It is more common in the elderly.
In this article. When you look at your prescription for eyeglasses, you will see numbers listed under the headings of OS and OD. They are Latin abbreviations: OS (oculus sinister) means the left eye and OD (oculus dextrus) means the right eye. Occasionally, you will see a notation for OU, which means something involving both eyes.
Pupil (Definition). The pupil is the opening in the iris inside of the eye though which light is focused on the retinal film at the back of the eye. The iris can open and close in response to light to vary the amount inside the eye.It is what looks red, in the red eye in photographs....Read more.upil (Definition). The pupil is the opening in the iris inside of the eye though which light is focused on the retinal film at the back of the eye. The iris can open and close in response to light to vary the amount inside the eye.