Can you explain the mechanism fever?

Yes I can :) Fever results from a chemical cascade in response to a pyrogen. Infection causes the release of pyrogens which in turn cause the body to produce a chemical called prostaglandin e2 (pge2). Pge2 then stimulates a special part of our brain's hypothalamous called the pre-optic area (poa). The poa then integrates this information and sends a signal to our autonomic nervous system to create heat.