Fever part II - Why is it dangerous to get high fever?

My son, who has fever, has woken up and is wondering why it is dangerous to have high fever, to reach 42 or 43 degrees Celsius. Could you dopers help me out with this too…?

The human body is full of chemical processes which work best in a certain range of temperatures. If things get too hot or too cold, molecules get bent out of shape and things don’t fit together properly.

If this goes on too long, it can put strain on the heart, mess with your brain (high fevers can cause hallucinations and delirium, and eventually brain damage) and dehydration.

Your average fever is nothing to worry too much about, except for the dehydration aspect, though. Fever also has some benefit to fighting off disease: it speeds up certain processes like the division of white blood cells, and a high temperature can make things uncomfortable for bacterial pathogens.

A fever that is generated by the body in response to an infection is not particularly dangerous, our society’s fever phobia notwithstanding. The question in those cases is what is causing the fever and how dangerous (or not) is that cause. Yes, fever can trigger a seizure in some children, generally during preschool years, but even that is usually fairly benign, albeit scary for a parent to see. Hydration. Keep the fever down for comfort’s sake, etc.

OTOH, a fever caused by external factors, such as an obese football player in full gear playing in 100 degrees … that’s potentially deadly. That’s a medical emergency. The brain isn’t ready for it and it malfunctions. Organs shut down.

Thanks for the replies, very interesting indeed, but I dont feel neither was an actual answer to my question. **friedo **: “If things get too hot or too cold, molecules get bent out of shape and things don’t fit together properly.” Could you elaborate on this?

DSeid, thanks for replying, but I don’t see how your reply is an answering to my question, why high fever is dangerous…?

That it usually isn’t.

molecules have shapes that fit with other molecules, think lock and key where only the right combinations work together. temperature can affect how well these molecules fit together to react.

molecules also break down and this breakdown can increase with temperature. living thing exist because the creation of new material and the repair of existing material happens faster than its breakdown.

A good review of the subject may be found in The neurobiology of hyperthermia By Hari Shanker Sharma. It’s a 500+ page tome with lots of references.

The danger of fever is more often derived from the cause of fever. If one is running a very high temperature because of an overwhelming infection, it is the consequences of the infection that may be deadly, rather than the fever. Death will probably come from circulatory collapse as the vascular system becomes leaky and fluids migrate into the lungs and tissues and blood pressure falls.

On the other hand, if fever is due to heat stroke, where overexposure to heat stress overwhelms the body’s ability to regulate its own internal temperature, then rising internal temperatures tend to cause central nervous system dysfunction, which oftentimes becomes fatal as the patient becomes delerious, then comatose, often with seizures thrown in. Even if this is not fatal, permanent brain damage is common. Meanwhile, death from dehydration in this situation is also not uncommon.

The mechanism for this effect of hyperthermia is not fully understood, but it appears that at high temperatures, the nervous system stops becoming a relatively coherent, regulated control system, and begins to ‘short circuit’, in a way that is often incompatable with life. Consult the linked text for a better description of what really goes on when temperature is high.

CMIIW, but i was told that if the body could be raised to 112 degrees F, that the AIDS virus could be killed off and the patient could be cured. The problem is that the human body only functions properly within a rather narrow temperature range. 112 F will kill it.

If that information is correct then there you have it. Fever fights infection but too high of a fever will interfere with other functions of the body and they will shut down.

BTW it seems that part of how fever helps fight off infection is that WBC receptors change their conformation slightly at different temperatures - as you go through a wider range of temperatures you increase the possibility that a WBC reacts to a particular germ’s antigens and responds to attack it.

Nothing to do with the op but hey, cool anyway! Fever is our friend - to a … degree … anyway.

That is an intruiging theory. But wouldn’t it mean that the antigens that the body started producing pre-fever stop working? And is it really true that the receptors change in a specific, repeatable way vs. just being randomly distorted? And would the body change the temperature up and down until it found the right point at which the right antibody is produced? And stay there? Fever varies over the course of the day. It all seems far fetched…

To illustrate the process to a kid, explain that you can warm a raw egg up a little and when it cools it will still be cear and runny, but if you heat it ‘too much’ it changes and it will stay white and solid even after it cools down. Chemicals in your body are more or less the same.

Someone has a few wires crossed. The naked virus (i.e. floating about in the bloodstream, or yet to insert itself into the cell DNA) might be killed (by any number of ideas), but an infected cell would not be cured of its infection. The only way to kill the DNA form of the HIV retrovirus in the cell is to kill the cell. It is in this form that it reproduces. So it is kill and cure.

HIV treatments, in general, try to stop the virus from infecting new cells. As do most antivirals. If the infection rate can be slowed it gives the immune system a chance to mop up, and once the infected cells all die, rid the body of infection. Viruses that don’t aggressively reproduce all the time, and bide their time secreted in a cell’s DNA, are hard, if not impossible, to be totally rid of. HIV is example of the moment. Chickenpox is another well known one.