Transcript The adaptive significance of Fever

The adaptive significance of Fever
Reese Clark
Why does fever occur?

Two hypothesis:
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Manipulation of the host by the pathogen.
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Adaptive defense against the infection.
Experimental Results
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Vaughn et al.
–
Vaughn studied
behavioral responses of
desert iguanas
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Allowed iguanas to
thermoregulate after
injection of either saline
or dead bacteria
Images from Freeman, S., Herron, J.C
Experimental Results
–
Kluger et al. performed 2
studies
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
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
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.
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
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.
Conclusions

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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.
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.
References
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Blatteis, C.M.2003. Fever: Pathological or Physiological,
injurious or beneficial? Journal of Thermal Biology. 28: 113.
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.