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.
And likewise, OS means left eye. The sphere in this case is -1.25 for the right eye, and -1.50 for the left eye. There is an important point to be made. Regardless of if there is a + or - before the sphere number, the rule of thumb is, the higher the number, the worse the eyesight.