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The adaptive significance of Fever

The adaptive significance of Fever. Reese Clark. Why does fever occur?. Two hypothesis: Manipulation of the host by the pathogen. Adaptive defense against the infection. Experimental Results. Vaughn et al. Vaughn studied behavioral responses of desert iguanas

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The adaptive significance of Fever

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  1. The adaptive significance of Fever Reese Clark

  2. Why does fever occur? • Two hypothesis: • Manipulation of the host by the pathogen. • Adaptive defense against the infection.

  3. Experimental Results • Vaughn et al. • Vaughn studied behavioral responses of desert iguanas • Allowed iguanas to thermoregulate after injection of either saline or dead bacteria Images from Freeman, S., Herron, J.C

  4. Experimental Results • Kluger et al. performed 2 studies • Desert Iguana infected with Aeromonas hydrophila and maintained and fixed temperatures. • Desert Iguana infected with A. hydrophila, treated with aspirin-like medicine. Images from Freeman, S., Herron, J.C

  5. Experimental Results • Manuel Banet • Studied effects of increased body temperature and metabolic rates in rats. • Rats had cooling devices implanted in either their brain or spinal cord • Rats with cooling devices in their brains were able to develop very high fevers and maintain somewhat normal metabolic rates. • Rats with cooling devices in their spinal cord showed greatly increased metabolic rates without increasing body temperature. • He also closely monitored body temperatures and metabolic rates in rats with and without implants, but none that were heated or cooled.

  6. Experimental Results • Doran et al. • Studied the effects of fever on chicken pox in children that were treated with a placebo and children that were treated with a fever reducer. Image from Freeman, S., Herron, J.C

  7. Experimental Results • Graham et al. • Studied adults infected with the common cold, whom were treated with either a placebo or a variety of OTC medicines. Images from Freeman, S., Herron, J.C.

  8. Conclusions • Fever is a beneficial adaptation in ectotherms to infections by certain pathogens. • Fever in endotherms is an adaptive response to infection, however is not limited completely to core temperature increase, but many other effects on the immune system. • Fever is not beneficial in all infections and carries many costs.

  9. Future Research Ideas • Decreased core temperature while allowing immune response continues as normal • Studies of the effects of presence or absence of fever in response to many different pathogens in endotherms and ectotherms.

  10. References • Blatteis, C.M.2003. Fever: Pathological or Physiological, injurious or beneficial? Journal of Thermal Biology. 28: 1- 13. • Freeman, S., Herron, J.C. 2007. Evolutionary Analysis. San Francisco, CA. Pearson Benjamin Cummings. • Jiang, D., Detolla, L. Sing, I.S., Gatdula, C., Fitzgerald, B., van Ruijen, N., Cross, A.S., Hasday, J.D. 1999. Exposure to Febrile Temperature upregulates expression of pyrogenic cytokines in endotoxin challenged mice. American Journal of Physiology. 276: 1653-1660.

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