Exogenous pyrogens (e.g. bacteria, viruses, toxins) initiate fever, usually within 2 h of exposure, by interacting with macrophages or monocytes, leading to cytokine induction. Other mechanisms to initiate fever include: Some endotoxins, produced by bacteria, act directly on the hypothalamus to alter the set point.

Why do pyrogens cause fever?

Fevers are caused by chemicals called pyrogens flowing in the bloodstream. Pyrogens make their way to the hypothalamus in the brain, which is in charge of regulating body temperature. When pyrogens bind to certain receptors in the hypothalamus, body temperature rises.

What is the effect of pyrogens on the body?

When bacterial pyrogens are injected in sufficient amounts, perhaps in microgram quantities, the fever produced is accompanied by chills, body aches, a rise in blood pressure, and possibly a state of shock and death.