question: If the human body uses fever to kill infections, why can’t a limb be heated up, say, in a container of water, to eliminate an infection?
comment: For one thing, that would only heat up the external temperature. Your body is actually designed to prevent any external temperatures from impacting your internal temperature. It will do everything it can to fight any temperature changes coming from the outside like that. Also, you can't just heat up one limb. That won't work. The body is filled with fluids, especially blood and the blood is constantly circulating. Any temperature changes for the most part are body wide. In extreme casts you can't do locatlized temperature changes like frostbite, but those also cause damage, often permanently, to the tissue. It takes something that extreme for normal bloodflow to not spread it out. It's how you can walk around in (not too severe) winter with a coat and hat and not freeze in spite of not having winter gear covering every inch of you.
passages: Cost benefit trade-off actuary issues apply to the antibacterial and antiviral effects of fever (increased body temperature). Fever has the future benefit of clearing infections since it reduces the replication of bacteria and viruses. But it also has great present metabolic (BMR) cost, and the risk of hyperpyrexia. Where it is achieved internally, each degree raise in blood temperature, raises BMR by 10–15%. 90% of the total cost of fighting pneumonia, goes, for example, on energy devoted to raising body temperature. During sepsis, the resulting fever can raise BMR by 55%—and cause a 15% to 30% loss of body mass. Circumstances in which fever deployment is not selected or is reduced include:
   Because of the broad variety of operating conditions, these devices must meet specific requirements concerning their rate and duration of cooling, their power source, and their adherence to health and safety regulations. Among other criteria are the user's need for physical mobility and autonomy. For example, active-liquid systems operate by chilling water and circulating it through a garment; the skin surface area is thereby cooled through conduction. This type of system has proven successful in certain military, law enforcement, and industrial applications. Bomb-disposal technicians wearing special suits to protect against improvised explosive devices (IEDs) use a small, ice-based chiller unit that is strapped to one leg; a liquid-circulating garment, usually a vest, is worn over the torso to maintain a safe core body temperature. By contrast, soldiers traveling in combat vehicles can face microclimate temperatures in excess of 65 °C and require a multiple-user, vehicle-powered cooling system with rapid connection capabilities. Requirements for hazmat teams, the medical community, and workers in heavy industry vary further.
   When body temperature is significantly elevated, mechanical cooling methods are used to remove heat and to restore the body's ability to regulate its own temperatures. Passive cooling techniques, such as resting in a cool, shady area and removing clothing can be applied immediately. Active cooling methods, such as sponging the head, neck, and trunk with cool water, remove heat from the body and thereby speed the body's return to normal temperatures. Drinking water and turning a fan or dehumidifying air conditioning unit on the affected person may improve the effectiveness of the body's evaporative cooling mechanisms (sweating).
   There is the further difficulty inherent in the devices delivering energy. Regional devices may not uniformly heat a target area, even without taking into account compensatory mechanisms of the body. A great deal of current research focuses on how one might precisely position heat-delivery devices (catheters, microwave and ultrasound applicators, etc.) using ultrasound or magnetic resonance imaging, as well as developing new types of nanoparticles that can more evenly distribute heat within a target tissue.
   Bathing or sponging with lukewarm or cool water can effectively reduce body temperature in those with heat illness, but not usually in those with fever. The use of alcohol baths is not an appropriate cooling method, because there have been reported adverse events associated with systemic absorption of alcohol.
  
  Section::::Medications.
  
  Many medications have antipyretic effects and thus are useful for fever but not in treating illness, including:
  
  BULLET::::- NSAIDs such as ibuprofen, naproxen, ketoprofen, and nimesulide
  
  BULLET::::- Aspirin, and related salicylates such as choline salicylate, magnesium salicylate, and sodium salicylate
  
  BULLET::::- Paracetamol (USAN and JAN: acetaminophen)
   There are arguments for and against the usefulness of fever, and the issue is controversial. There are studies using warm-blooded vertebrates with some suggesting that they recover more rapidly from infections or critical illness due to fever. Studies suggest reduced mortality in bacterial infections when fever was present.
  
  In theory, fever can aid in host defense. There are certainly some important immunological reactions that are sped up by temperature, and some pathogens with strict temperature preferences could be hindered.
  
  Research has demonstrated that fever assists the healing process in several important ways:
  
  BULLET::::- Increased mobility of leukocytes
   Treatment to reduce fever is generally not required. Treatment of associated pain and inflammation, however, may be useful and help a person rest. Medications such as ibuprofen or paracetamol (acetaminophen) may help with this as well as lower temperature. Measures such as putting a cool damp cloth on the forehead and having a slightly warm bath are not useful and may simply make a person more uncomfortable. Children younger than three months require medical attention, as might people with serious medical problems such as a compromised immune system or people with other symptoms. Hyperthermia does require treatment.
   Methods in preventing amputation, limb-sparing techniques, depend on the problems that might cause amputations to be necessary. Chronic infections, often caused by diabetes or decubitus ulcers in bedridden patients, are common causes of infections that lead to gangrene, which would then necessitate amputation.
  
  There are two key challenges: first, many patients have impaired circulation in their extremities, and second, they have difficulty curing infections in limbs with poor vasculation (blood circulation).
   Medical devices often include fan-cooled heat sinks, to cool their electronic components. While these systems sometimes include HEPA filters to collect microbes, some pathogens do pass through these filters, collect inside the device and are eventually blown out and infect other patients. Devices used in operating rooms rarely include fans, so as to minimize the chance of transmission. Also, medical equipment, high-end computers, swimming pools, drinking-water systems and other products that utilize liquid lines run the risk of biofouling as biological growth occurs inside them.
   As of 2004, such an application of anhydrobiosis is being applied to vaccines. In vaccines, the process can produce a dry vaccine that reactivates once it is injected into the body. In theory, dry-vaccine technology could be used on any vaccine, including live vaccines such as the one for measles. It could also potentially be adapted to allow a vaccine's slow release, eliminating the need for boosters. This proposes to eliminate the need for refrigerating vaccines, thus making dry vaccines more widely available throughout the developing world where refrigeration, electricity, and proper storage are less accessible.
   Limited supplies and resources may prevent a health facility from using all the standard precautions all the time. However, health facilities should establish and maintain a basic, practical level of standard precautions that can be used routinely with patients in their health facility. This requires a source of clean water, routine handwashing before and after any contact with a person who has fever, and safe handling and disposal of sharp instruments and equipment.
   The amphibian chytrid fungus appears to grow best between 17 and 25 °C, and exposure of infected frogs to high temperatures can cure the frogs. In nature, the more time individual frogs were found at temperatures above 25 °C, the less likely they were to be infected by the amphibian chytrid. This may explain why chytridiomycosis-induced amphibian declines have occurred primarily at higher elevations and during cooler months. Naturally produced cutaneous peptides can inhibit the growth of "B. dendrobatidis" when the infected amphibians are around temperatures near 10 °C (50 °F), allowing species like the northern leopard frog ("Rana pipiens") to clear the infection in about 15% of cases.
   Some limited evidence supports sponging or bathing feverish children with tepid water. The use of a fan or air conditioning may somewhat reduce the temperature and increase comfort. If the temperature reaches the extremely high level of hyperpyrexia, aggressive cooling is required (generally produced mechanically via conduction by applying numerous ice packs across most of the body or direct submersion in ice water). In general, people are advised to keep adequately hydrated. Whether increased fluid intake improves symptoms or shortens respiratory illnesses such as the common cold is not known.
  
  Section::::Management.:Medications.
   Activating the immune system has the present and future benefit of clearing infections, but it is also both expensive in regard to present high metabolic energy consumption, and in the risk of resulting in a future immune related disorder. Therefore, an adaptive advantage exists if an animal can control its deployment in regard to actuary-like evaluations of future benefits and costs as to its biological fitness. In many circumstances, such trade-off calculations explain why immune responses are suppressed and infections are tolerated. Circumstances where immunity is not activated due to lack of an actuarial benefit include:
  
  BULLET::::- Malnutrition
   Pyrotherapy
  
  Pyrotherapy (artificial fever) is a method of treatment by raising the body temperature or sustaining an elevated body temperature (caused by a fever). In general, the body temperature was maintained at 41°C (105°F). Many diseases were treated by this method in the first half of the 20th century. In general, it was done by exposing the patient to hot baths, warm air, or (electric) blankets.
  
  Section::::Use.
  
  One example is the malariotherapy, the treatment of syphilis by the introduction of malaria, for which Julius Wagner-Jauregg won the Nobel Prize for Medicine in 1927.
   BULLET::::3. Steaming ("futha") – Medicinal herbs are commonly inhaled by steaming them in a bucket of boiling water. A blanket is used to cover the patient and container. Hot rocks or a portable stove may be included to keep the bucket boiling. The patient sits under the blanket or plastic(preferably) as blankets get to absorb the heat and the steam doesn't rotate well, breathes in the herbal steam and sweats.
   With these technologies, cold water circulates through a blanket, or torso wraparound vest and leg wraps. To lower temperature with optimal speed, 70% of a person's surface area should be covered with water blankets. The treatment represents the most well studied means of controlling body temperature. Water blankets lower a person's temperature exclusively by cooling a person's skin and accordingly require no invasive procedures.
   However, legionella can be safely and easily controlled with good design and engineering protocols. For instance raising the temperature of water heaters once a day or even once every few days to at the coldest part of the water heater for 30 minutes effectively controls legionella. In all cases and in particular energy efficient applications, Legionnaires' disease is more often than not the result of engineering design issues that do not take into consideration the impact of stratification or low flow.
   If fever-reducing drugs lower the body temperature, even if the temperature does not return entirely to normal, then hyperthermia is excluded.
  
  Section::::Prevention.
   Currently, no vaccine against relapsing fever is available, but research continues. Developing a vaccine is very difficult because the spirochetes avoid the immune response of the infected person (or animal) through antigenic variation. Essentially, the pathogen stays one step ahead of antibodies by changing its surface proteins. These surface proteins, lipoproteins called variable major proteins, have only 30–70% of their amino acid sequences in common, which is sufficient to create a new antigenic "identity" for the organism. Antibodies in the blood that are binding to and clearing spirochetes expressing the old proteins do not recognize spirochetes expressing the new ones. Antigenic variation is common among pathogenic organisms. These include the agents of malaria, gonorrhea, and sleeping sickness. Important questions about antigenic variation are also relevant for such research areas as developing a vaccine against HIV and predicting the next influenza pandemic.
   Jenner inoculated Phipps in both arms that day, subsequently producing in Phipps a fever and some uneasiness, but no full-blown infection. Later, he injected Phipps with variolous material, the routine method of immunization at that time. No disease followed. The boy was later challenged with variolous material and again showed no sign of infection.
   An organism at optimum temperature is considered "afebrile" or "apyrexic", meaning "without fever". If temperature is raised, but the setpoint is not raised, then the result is hyperthermia.
  
  Section::::Concepts.:Hyperthermia.
   BULLET::::- Aged individuals—the burden of tolerating infection will exist for a short time which reduces the actuarial future benefits of clearing an infection compared to the costs of its removal. This change favors reduced or no deployment of fever.
  
  BULLET::::- When internal resources are limited (such as in winter), and the ability to afford high expenditure on increased metabolism is reduced. This increases the risks of activating fever relative to its potential benefit, and animals are less likely to use fever to fight infections.
  
  BULLET::::- Late Pregnancy
  
  Section::::Antioxidants.
   In healthy adults, the range of normal, healthy temperatures for oral temperature is , for rectal it is , for tympanic membrane (the ear drum) it is , and for axillary (the armpit) it is . Harrison's Principles of Internal Medicine defines a fever as a morning oral temperature of 37.2 °C (98.9 °F) or an afternoon oral temperature of 37.7 °C (99.9 °F) while the normal daily temperature variation is typically 0.5 °C (0.9 °F).
   This was first demonstrated by Khalaf Bushara and colleagues as the first nonmuscular use of BTX-A in 1993. BTX-A has since been approved for the treatment of severe primary axillary hyperhidrosis (excessive underarm sweating of unknown cause), which cannot be managed by topical agents. 
  
  A microwave-based device has been tried for excessive underarm perspiration and appears to show promise.
  
  Tap water iontophoresis as a treatment for palmoplantar hyperhidrosis was originally described in the 1950s. Studies showed positive results and good safety with tap water iontophoresis. One trial found it decreased sweating by about 80%.
  
  Section::::Treatment.:Surgery.
  
presuppositions: Apply heat to raise external temperature will also easily raise internal temperature. Heating a limb in a container of water could heat internal temperatures.
corrections: The body has very strong defense from letting external temperatures affect internal temperatures. Heating a limb in a container of water would only heat external temperatures.
raw_presuppositions: Apply heat to raise external temperature will also easily raise internal temperature. Heating a limb in a container of water could heat internal temperatures.
raw_corrections: The body has very strong defense from letting external temperatures affect internal temperatures. Heating a limb in a container of water would only heat external temperatures.