Why cold water helps to overcome from high fever in body? As fever is inside the body and we're applying cold water over the body!
As far as how the water cools the body it's simply a matter of physics. Water has a higher specific heat also called heat capacity than the air, clothes, or other matter that normally surrounds the body.Specific heat refers to the amount of heat (keep in mind that heat is essentially the measure of the average movements of the molecules in a substance) per unit of mass it would take to raise it's temperature by 1 degree Celsius. Water is useful for temperature regulation because it takes so much energy for it to change temperatures. Metals tend to have low specific heats which is why we make frying pans out of metals like iron. They take less energy to become hot.
As systems naturally fall back to equilibrium, if the body is hotter than the water heat will be transferred from the body into the water until they are the same temperature which will be a lot closer to the temperature of the water (compared to the initial temp of the body) because changing the temperature of water 1 degree takes more heat energy than changing the same mass of human to change 1 degree in temperature.
While this primarily acts on the outer portions of the body, the process continues into the core of the body as now instead of having hot skin and cold water, you have hot muscles and cold skin, from there you have hot organs and cold muscles, and so on and so on.
I hope this is helpful! For more information on specific heat you can check out: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/spht.html
Fever is triggered when pyrogens cause release of prostaglandin that acts on hypothalamus (which is the center of thermoregulation).
Fever assists in the healing process by:
- enhancing phagocytosis
- decreasing negative effects of endotoxins
- stimulates proliferation of lymphocytes
Although is a good reaction, when the temperature gets too high it could determine negative effects, like convulsions at children. Brain damage appears when the temperature rises as much as 42 degrees Celsius, and most febrile conditions go up to 40.6 degrees Celsius.
So fever must be kept under control, and cold water helps lowering body temperature. Lowering the temperature will prevent negative effects of fever. Cold water is a symptomatic treatment for fever. Most important is to determine cause of fever and do an ethiological treatment.
Source: Wikipedia contributors, "Fever," Wikipedia, The Free Encyclopedia, http://en.wikipedia.org/w/index.php?title=Fever&oldid=614212619 (accessed June 27, 2014).