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.
OD is an abbreviation for the Latin oculus dexter, meaning right eye. OS is an abbreviation for the Latin oculus sinister, meaning left eye. The first number after the determination of which eye is the sphere. A negative number indicates myopia. A positive number indicates hyperopia. The second number in this prescription is the cylinder (astigmatism), and the third number is the axis of the cylinder component. The axis of the astigmatism does not relate to the amount of cylinder, just the location of the irregularity.