There are many mysteries around fever, but we do know that all mammals, some birds and even a few invertebrate and plant species feel fever's heat. It has persisted for over 600 million years of evolution. But it has a significant cost: for every degree increase in temperature, there's a 12.5% increase in energy required. So, why and how does your body produce a fever? Christian Moro investigates. [Directed by Artrake Studio, narrated by Addison Anderson].

Christian Moro: Why do you get a fever when you're sick?

Why do you get a fever when you're sick?

Heat shock proteins (HSPs) are unsung heroes in fevers, speeding immune cells to infection sites and curtailing viral spread.

Malaria's fever once fought syphilis—quinine then cured malaria, a risky yet effective treatment technique until penicillin.

Fever boosts immune response—increased heat aids lymphocytes' travel to infection sites, enhancing body's defense mechanisms.