Fever and survival: the role of serum iron.

Abstract

The effects of bacterial infection and temperature on serum Fe levels were investigated in the lizard Dipsosaurus dorsalis. Changes in body temperature from normal (38.degree. C) to febrile (41.degree. C) did not alter serum Fe levels. Injection with Aeromonas hydrophila led to a significant reduction in serum Fe levels, comparable to that found in mammals. This reduction in serum Fe level was independent of the lizard''s body temperature. When grown in vitro, A. hydrophila grew equally well at afebrile (38.degree. C) and febrile (41.degree. C) temperatures. When the Fe levels of the growth medium were reduced, the bacterial growth was diminished at the febrile temperature but was not significantly affected at the afebrile temperature. The addition of Fe supplements to bacterially infected lizards led to an increase in the percent mortality. One of the mechanisms behind the beneficial, or adaptive value of fever in D. dorsalis may be the decrease in Fe available to the pathogenic microorganisms.