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Fever

Fever

Definition

A fever is any body temperature elevation over 100.4°F (38°C).

Description

A healthy person's body temperature fluctuates between 97°F (36.1°C) and 100°F (37.8°C), with the average being 98.6°F (37°C). The body maintains stability within this range by balancing the heat produced by the metabolism with the heat lost to the environment. The "thermostat" that controls this process is located in the hypothalamus, a small structure located deep within the brain. The nervous system constantly relays information about the body's temperature to the thermostat, which in turn activates different physical responses designed to cool or warm the body, depending on the circumstances. These responses include: decreasing or increasing the flow of blood from the body's core, where it is warmed, to the surface, where it is cooled; slowing down or speeding up the rate at which the body turns food into energy (metabolic rate); inducing shivering, which generates heat through muscle contraction; and inducing sweating, which cools the body through evaporation.

A fever occurs when the thermostat resets at a higher temperature, primarily in response to an infection. To reach the higher temperature, the body moves blood to the warmer interior, increases the metabolic rate, and induces shivering. The chills that often accompany a fever are caused by the movement of blood to the body's core, leaving the surface and extremities cold. Once the higher temperature is achieved, the shivering and chills stop. When the infection has been overcome or drugs such as aspirin or acetaminophen have been taken, the thermostat resets to normal and the body's cooling mechanisms switch on: the blood moves to the surface and sweating occurs.

Fever is an important component of the immune response, though its role is not completely understood. Physicians believe that an elevated body temperature has several effects. The immune system chemicals that react with the fever-inducing agent and trigger the resetting of the thermostat also increase the production of cells that fight off the invading bacteria or viruses. Higher temperatures also inhibit the growth of some bacteria, while at the same time speeding up the chemical reactions that help the body's cells repair themselves. In addition, the increased heart rate that may accompany the changes in blood circulation also speeds the arrival of white blood cells to the sites of infection.

Demographics

Fevers are components of many disease entities. Virtually all persons experience fevers at some time in their lives. Elevations in temperature are not reportable events. Thus, accurate data regarding the prevalence of fevers are not available.

Causes and symptoms

Fevers are primarily caused by viral or bacterial infections, such as pneumonia or influenza . However, other conditions can induce a fever, including allergic reactions; autoimmune diseases; trauma, such as breaking a bone; cancer ; excessive exposure to the sun; intense exercise ; hormonal imbalances; certain drugs; and damage to the hypothalamus. When an infection occurs, fever-inducing agents called pyrogens are released, either by the body's immune system or by the invading cells themselves that trigger the resetting of the thermostat. In other circumstances, the immune system may overreact (allergic reactions) or become damaged (autoimmune diseases), causing the uncontrolled release of pyrogens. A stroke or tumor can damage the hypothalamus, causing the body's thermostat to malfunction. Excessive exposure to the sun or intense exercise in hot weather can result in heat stroke, a condition in which the body's cooling mechanisms fail. Malignant hyperthermia is a rare, inherited condition in which a person develops a very high fever when given certain anesthetics or muscle relaxants in preparation for surgery.

How long a fever lasts and how high it may go depends on several factors, including its cause, the age of the person, and his or her overall health. Most fevers caused by infections are acute, appearing suddenly and then dissipating as the immune system defeats the infectious agent. An infectious fever may also rise and fall throughout the day, reaching its peek in the late afternoon or early evening. A low-grade fever that lasts for several weeks is associated with autoimmune diseases such as lupus or with some cancers, particularly leukemia and lymphoma.

When to call the doctor

A doctor or other healthcare provider should be called when a fever does not resolve after two to three days. Anyone with a fever over 104°F (40.0°C) should seek immediate medical treatment.

A doctor should be called when an infant's temperature rises above 100°F (37.8°C) and cannot be brought down within a few minutes. Infants whose temperatures exceed 102°F (38.9°C) should be immersed in warm or tepid water to help reduce temperature slowly, while waiting for emergency help to arrive.

Diagnosis

A fever is usually diagnosed using a thermometer. A variety of different thermometers are available. Glass thermometer should not be used since they can break and release mercury, which is toxic. Digital thermometers can and should be used in place of glass thermometers rectally, orally, and under the arm in all age groups. Electronic thermometers can be inserted in the ear to quickly register the body's temperature.

As important as registering a person's temperature is determining the underlying cause of the fever. The presence or absence of accompanying symptoms, a person's medical history, and information about what he or she may have ingested, any recent trips taken, or possible exposures to illness all help the physician make a diagnosis. Blood tests can aid in identifying an infectious agent by detecting the presence of antibodies against it or providing samples for growth of the organism in a culture. Blood tests can provide the doctor with white blood cell counts. Ultrasound tests, magnetic resonance imaging (MRI) tests, or computed tomography (CT) scans may be ordered if the doctor cannot readily determine the cause of a fever.

Treatment

Physicians agree that the most effective treatment for a fever is to address its underlying cause, such as through the administration of antibiotics . Also, because a fever helps the immune system fight infection, it usually should be allowed to run its course. Drugs to lower fever (antipyretics) can be given if a person (particularly a child) is uncomfortable. These include acetaminophen and ibuprofen. Aspirin, however, should not be given to a child or adolescent with a fever since this drug has been linked to an increased risk of Reye's syndrome . Bathing a person in tepid water can also help alleviate a high fever.

A fever requires emergency treatment under the following circumstances:

  • newborn (three months or younger) with a fever over 100.5°F (38°C)
  • infant or child with a fever over 103°F (39.4°C)
  • fever accompanied by severe headache , neck stiffness, mental confusion, or severe swelling of the throat

A very high fever in a small child can trigger seizures (febrile seizures ) and, therefore, should be treated immediately. A fever accompanied by the above symptoms can indicate the presence of a serious infection, such as meningitis , and should be brought to the immediate attention of a physician.

KEY TERMS

Antipyretic drug Medications, like aspirin or acetaminophen, that lower fever.

Autoimmune disorder One of a group of disorders, like rheumatoid arthritis and systemic lupus erythematosus, in which the immune system is overactive and has lost the ability to distinguish between self and non-self. The body's immune cells turn on the body, attacking various tissues and organs.

Febrile seizure Convulsions brought on by fever.

Hyperthermia Body temperature that is much higher than normal (i.e. higher than 98.6°F).

Malignant hyperthermia A type of reaction (probably with a genetic origin) that can occur during general anesthesia and in which the patient experiences a high fever, muscle rigidity, and irregular heart rate and blood pressure.

Meningitis An infection or inflammation of the membranes that cover the brain and spinal cord. It is usually caused by bacteria or a virus.

Metabolism The sum of all chemical reactions that occur in the body resulting in growth, transformation of foodstuffs into energy, waste elimination, and other bodily functions. These include processes that break down substances to yield energy and processes that build up other substances necessary for life.

Pyrogen A chemical circulating in the blood that causes a rise in body temperature.

Reye's syndrome A serious, life-threatening illness in children, usually developing after a bout of flu or chickenpox, and often associated with the use of aspirin. Symptoms include uncontrollable vomiting, often with lethargy, memory loss, disorientation, or delirium. Swelling of the brain may cause seizures, coma, and in severe cases, death.

Prognosis

Most fevers caused by infection end as soon as the immune system rids the body of the pathogen, and these fevers do not produce lasting effects. The prognosis for fevers associated with more chronic conditions, such as autoimmune disease, depends upon the overall outcome of the disorder.

Prevention

Fevers may be prevented by avoiding the various diseases that cause them.

Nutritional concerns

Adequate nutrition via a well-balanced diet and sufficient intake of liquid help to reduce many fevers. Adequate intake of electrolytes such as sodium, chloride, potassium, phosphate, and bicarbonate helps to prevent dehydration that often accompanies a fever.

Parental concerns

Parents should carefully monitor their infants and young children for symptoms of fever. Any fever that exceeds 103°F (39.4°C) for more than a few minutes should be promptly treated.

Resources

BOOKS

Barlam, Tamar F., and Dennis L. Kasper. "Approach to the Acutely Ill Infected Febrile Patient." In Harrison's Principles of Internal Medicine, 15th ed. Edited by Eugene Braunwald et al. New York: McGraw-Hill, 2001, pp. 95101.

Beutler, Bruce, and Steven M. Beutler. "The Pathogenesis of Fever." In Cecil Textbook of Medicine, 22nd ed. Edited by Lee Goldman et al. Philadelphia: Saunders, 2003, pp. 173032.

Bisno, Alan L. "Rheumatic Fever." In Cecil Textbook of Medicine, 22nd ed. Edited by Lee Goldman et al. Philadelphia: Saunders, 2003, pp. 178893.

Dale, David C. "The Febrile Patient." In Cecil Textbook of Medicine, 22nd ed. Edited by Lee Goldman et al. Philadelphia: Saunders, 2003, pp. 172930.

Dinarello, Charles A., and Jeffrey A. Gelfand. "Fever and Hyperthermia." In Harrison's Principles of Internal Medicine, 15th ed. Edited by Eugene Braunwald et al. New York: McGraw-Hill, 2001, pp. 914.

Dumler, J. Stephen. "Q Fever (Coxiella burnetii)." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 100910.

. "Spotted Fever Group Rickettsioses." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 9991003.

Halstead, Scott B. "Yellow Fever." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 10956.

. "Dengue Fever and Dengue Hemorrhagic Fever." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 10924.

Kaye, Elaine T., and Kenneth M. Kaye. "Fever and Rash." In Harrison's Principles of Internal Medicine, 15th ed. Edited by Eugene Braunwald et al. New York: McGraw-Hill, 2001, pp. 95101.

Powell, Keith R. "Fever without a Focus." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 8415.

. "Fever." In Nelson Textbook of Pediatrics, 17th ed. Edited by Richard E. Behrman et al. Philadelphia: Saunders, 2003, pp. 83940.

PERIODICALS

Dinarello, C. A. "Infection, fever, and exogenous and endogenous pyrogens: some concepts have changed." Journal of Endotoxin Research 10, no. 4 (2004): 20122.

Galache, C., et al. "Q fever: a new cause of 'doughnut' granulomatous lobular panniculitis." British Journal of Dermatology 151, no. 3 (2004): 6857.

Huang, S. Y., et al. "Effect of Recent Antipyretic Use on Measured Fever in the Pediatric Emergency Department." Archives of Pediatric and Adolescent Medicone 158, no. 10 (2004): 9726.

ORGANIZATIONS

American Academy of Emergency Medicine. 611 East Wells St., Milwaukee, WI 53202. Web site: <www.aaem.org/>.

American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 600071098. Web site: <www.aap.org/>.

American Association of Naturopathic Physicians. 8201 Greensboro Drive, Suite 300, McLean, VA 22102. Web site: <naturopathic.org/>.

American Society of Clinical Pathologists. 2100 West Harrison Street, Chicago IL 60612. Web site: <www.ascp.org/index.asp>.

College of American Pathologists. 325 Waukegan Road, Northfield, IL 60093. Web site: <www.cap.org/>.

Meningitis Foundation of America Inc. 7155 Shadeland Station, Suite 190, Indianapolis, IN 462563922. Web site: <www.musa.org/default.htm>.

WEB SITES

"Fever." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/ency/article/003090.htm> (accessed January 6, 2005).

"Typhoid Fever." Centers for Disease Control and Prevention. Available online at <www.cdc.gov/ncidod/dbmd/diseaseinfo/typhoidfever_g.htm> (accessed January 6, 2005).

"Yellow Fever." Centers for Disease Control and Prevention. Available online at <www.cdc.gov/travel/diseases/yellowfever.htm> (accessed January 6, 2005).

"Yellow Fever." World Health Organization. Available online at <www.who.int/csr/disease/yellowfev/en/> (accessed January 6, 2005).

L. Fleming Fallon Jr., MD, DrPH

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Fallon, L.. "Fever." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

Fallon, L.. "Fever." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1G2-3447200235.html

Fallon, L.. "Fever." Gale Encyclopedia of Children's Health: Infancy through Adolescence. 2006. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3447200235.html

Fever

Fever

Definition

A fever is a rise in body temperature to greater than 100°F (37.8°C).

Description

A healthy person's body temperature fluctuates between 97°F (36.1°C) and 100°F (37.8°C), with the average being 98.6°F (37°C). The body maintains stability within this range by balancing the heat produced by the metabolism with the heat lost to the environment. The "thermostat" that controls this process is located in the hypothalamus, a small structure located deep within the brain. The nervous system constantly relays information about the body's temperature to the thermostat. In turn, the thermostat activates different physical responses designed to cool or warm the body, depending on the circumstances. These responses include:

  • decreasing or increasing the flow of blood from the body's core, where it is warmed, to the surface, where it is cooled
  • slowing down or speeding up the rate at which the body turns food into energy (metabolic rate)
  • inducing shivering, which generates heat through muscle contraction
  • inducing sweating, which cools the body through evaporation

A fever occurs when the body's thermostat resets at a higher temperature, which primarily happens in response to an infection. To reach the higher temperature, the body moves blood to the warmer interior, increases the metabolic rate, and induces shivering. The chills that often accompany a fever are caused by the movement of blood to the body's core, which leaves the surface and extremities cold. Once the body reaches the higher temperature, the shivering and chills stop. When the infection has been overcome or drugs such as aspirin or acetaminophen (Tylenol) have

been taken, the thermostat resets to normal. When this happens, the body's cooling mechanisms switch on. The blood moves to the surface and sweating occurs.

Fever is an important component of the immune response, though its role is not completely understood. Physicians believe that an elevated body temperature has several effects. Certain chemicals in the immune system react with the fever-inducing agent and trigger the resetting of the thermostat. These immune system chemicals also increase the production of cells that fight off the invading bacteria or viruses. Higher temperatures also inhibit the growth of some bacteria and speed up the chemical reactions that help the body's cells repair themselves. Changes in blood circulation may cause the heart rate to increase, which speeds the arrival of white blood cells to the sites of infection.

Causes & symptoms

Fevers are primarily caused by viral or bacterial infections , such as pneumonia or influenza . However, other conditions can induce a fever, including these:

  • allergic reactions
  • autoimmune diseases
  • trauma, such as breaking a bone
  • cancer
  • excessive exposure to the sun
  • intense exercise
  • hormonal imbalances
  • certain drugs
  • damage to the hypothalamus

When an infection occurs, fever-inducing agents called pyrogens are released, either by the body's immune system or by the invading cells themselves. These pyrogens trigger the resetting of the thermostat. In other circumstances, an uncontrolled release of pyrogens may occur when the immune system overreacts due to an allergic reaction or becomes damaged due to an autoimmune disease. A stroke or tumor can damage the hypothalamus, causing the body's thermostat to malfunction. Excessive exposure to the sun or intense exercise in hot weather can result in heat stroke, a condition in which the body's cooling mechanisms fail. Malignant hyperthermia is a rare, inherited condition in which a person develops a very high fever when given certain anesthetics or muscle relaxants in preparation for surgery.

A recent study showed that most parents have misconceptions about fever and view it as a disease rather than a symptom. How long a fever lasts and how high it may go depend on several factors, including its cause and the patient's age and overall health. Most fevers caused by infections are acute, appearing suddenly and then dissipating as the immune system defeats the infectious agent. An infectious fever may also rise and fall throughout the day, reaching its peak in the late afternoon or early evening. A low-grade fever that lasts for several weeks is associated with autoimmune diseases such as lupus or with some cancers, particularly leukemia and lymphoma.

Diagnosis

A fever is usually diagnosed using a thermometer. A variety of different thermometers are available, including traditional oral and rectal thermometers made of glass and mercury, and more sophisticated electronic ones that can be inserted in the ear. For adults and older children, temperature readings are usually taken orally. Younger children who cannot or will not hold a thermometer in their mouths can have their temperatures taken by placing an oral thermometer under their armpits. Infants generally have their temperature taken rectally using a rectal thermometer.

As important as registering a patient's temperature is determining the underlying cause of the fever. The physician can make a diagnosis by checking for accompanying symptoms and by reviewing the patient's medical history, any recent trips he or she has taken, what he or she may have ingested, or any illnesses he or she has been exposed to. Blood tests hold additional clues. Anti-bodies in the blood point to the presence of an infectious agent, which can be verified by growing the organism in a culture. Blood tests can also provide the doctor with white blood cell counts. Ultrasound tests, magnetic resonance imaging (MRI) tests, or computed tomography (CT) scans may be ordered if the doctor cannot readily determine the cause of a fever.

Treatment

Often, doctors must remind patients, especially parents, not to "overtreat" low fevers but to remember that they are symptoms of an underlying disease or condition. Alternative therapies for treatment of fever focus not only on reducing fever but also on boosting the immune function to help the body fight infections more effectively. They include nutritional therapy, herbal therapy and traditional Chinese medicine .

Nutritional therapy

Naturopaths often recommend that patients take high doses of vitamin C to ward off diseases and prevent fever. In addition to vitamin C, other antioxidants such as vitamin A and zinc also boost the immune function. Naturopaths may also suggest reducing sugar intake (even fruit juices) because sugar depresses the immune system. To replace fluid that is lost during fever, patients are advised to drink vegetable juices and eat soups.

Herbal therapy

Western herbalists use tea preparations containing herbs such as bupleurum root or boneset to reduce fever. Mild herbs such as peppermint , elderflower, or yarrow can provide comfort to the child who has a mild fever. Others believe in sweating a fever out, literally. They often recommend that patients take hot baths to induce sweating. This helps induce or increase fever, which is believed to help the body get rid of infections.

Chinese medicine (TCM) offers many herbs and formulas for fevers. There are many distinct kinds of fevers, also called heat syndromes. For example, an excess-heat syndrome is characterized by a high fever, great thirst, and lots of sweating. Deficiency heat syndrome is characterized by a low-grade fever with afternoon fevers or night sweats. For excess heat, herbs that are dispersing and cold in nature are used. For chronic and low-grade fevers, herbs that tonify the yin (cooling aspect) are used as well as herbs that get rid of heat. There are even herbs such as bupleurum root (called Chai Hu in TCM) that are used for intermittent fevers or conditions alternating between fever and chills. Alternating fevers and chills occur in malaria , conditions connected to AIDS, chronic fatigue syndrome , and Epstein-Barr virus. The individual pattern should be diagnosed by a trained practitioner.

Aromatherapy

Patients can reduce feverish symptoms by inhaling essential oils of camphor, eucalyptus , lemon, and hyssop . These oils can also be mixed with an unscented body lotion or a vegetable oil for aromatherapy massage.

Homeopathy

Homeopathic doctors may prescribe herbal remedies based on the patient's overall personality profile as well as specific symptoms.

Allopathic treatment

Physicians agree that the most effective treatment for a fever is to address its underlying cause. Also, because a fever helps the immune system fight infection, some clinicians suggest it be allowed to run its course. Drugs to lower fever (antipyretics) can be given if a patient (particularly a child) is uncomfortable. These include aspirin, acetaminophen (Tylenol), and ibuprofen (Advil). Aspirin, however, should not be given to a child or adolescent with a fever since this drug has been linked to an increased risk of Reye's syndrome. Sponging a child or infant with tepid (lukewarm) water can also help reduce mild fevers.

A fever requires emergency treatment under the following circumstances:

  • Newborn (three months or younger) with a fever above 100.5°F (38°C).
  • Infant or child with a fever above 103°F (39.4°C). A very high fever in a small child can trigger seizures (febrile seizures) and therefore should be treated immediately.
  • Fever accompanied by severe headache , neck stiffness, mental confusion, or severe swelling of the throat. A fever accompanied by these symptoms can indicate the presence of a serious infection, such as meningitis , and should be brought to the immediate attention of a physician.

Expected results

Most fevers caused by infection end as soon as the immune system rids the body of the pathogen. Most fevers do not produce any lasting effects. The prognosis for fevers associated with more chronic conditions, such as autoimmune disease, depends upon the overall outcome of the disorder.

Resources

BOOKS

Bennett, J. Claude, and Fred Plum, eds. Cecil Textbook of Medicine. Philadelphia: W. B. Saunders, 1996.

"Children's Health." In Alternative Medicine: The Definitive Guide, compiled by The Burton Goldberg Group. Tiburon, CA: Future Medicine Publishing, 1999.

"Fever and Chills." In Reader's Digest Guide to Medical Cures and Treatment. New York: Reader's Digest Association, 1996.

Gelfand, Jeffrey, et al. "Fever, Including Fever of Unknow Origin." In Harrison's Principles of Internal Medicine, edited by Kurt Isselbacher, et al. New York: McGraw-Hill, 1997.

Tierney, Lawrence M., M.D., et al., eds. Current Medical Diagnosis and Treatment. Stamford, CT: Appleton & Lange, 1996.

PERIODICALS

Bernath, Vivienne F."Tepid Sponging and Paracetamol for Reduction of Body Temperature in Febrile Children." The Medical Journal of Australia (February 4, 2002):130.

Huffman, Grace B. "Parental Misconceptions about Fever in Children." American Family Physician (February 1, 2002):482.

Mai Tran

Teresa G. Odle

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Tran, Mai; Odle, Teresa. "Fever." Gale Encyclopedia of Alternative Medicine. 2005. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

Tran, Mai; Odle, Teresa. "Fever." Gale Encyclopedia of Alternative Medicine. 2005. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1G2-3435100308.html

Tran, Mai; Odle, Teresa. "Fever." Gale Encyclopedia of Alternative Medicine. 2005. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3435100308.html

Fever

Fever

Definition

A fever is any body temperature elevation over 100 °F (37.8 °C).

Description

A healthy person's body temperature fluctuates between 97 °F (36.1 °C) and 100 °F (37.8 °C), with the average being 98.6 °F (37 °C). The body maintains stability within this range by balancing the heat produced by the metabolism with the heat lost to the environment. The "thermostat" that controls this process is located in the hypothalamus, a small structure located deep within the brain. The nervous system constantly relays information about the body's temperature to the thermostat, which in turn activates different physical responses designed to cool or warm the body, depending on the circumstances. These responses include: decreasing or increasing the flow of blood from the body's core, where it is warmed, to the surface, where it is cooled; slowing down or speeding up the rate at which the body turns food into energy (metabolic rate); inducing shivering, which generates heat through muscle contraction; and inducing sweating, which cools the body through evaporation.

A fever occurs when the thermostat resets at a higher temperature, primarily in response to an infection. To reach the higher temperature, the body moves blood to the warmer interior, increases the metabolic rate, and induces shivering. The "chills" that often accompany a fever are caused by the movement of blood to the body's core, leaving the surface and extremities cold. Once the higher temperature is achieved, the shivering and chills stop. When the infection has been overcome or drugs such as aspirin or acetaminophen (Tylenol) have been taken, the thermostat resets to normal and the body's cooling mechanisms switch on: the blood moves to the surface and sweating occurs.

Fever is an important component of the immune response, though its role is not completely understood. Physicians believe that an elevated body temperature has several effects. The immune system chemicals that react with the fever-inducing agent and trigger the resetting of the thermostat also increase the production of cells that fight off the invading bacteria or viruses. Higher temperatures also inhibit the growth of some bacteria, while at the same time speeding up the chemical reactions that help the body's cells repair themselves. In addition, the increased heart rate that may accompany the changes in blood circulation also speeds the arrival of white blood cells to the sites of infection.

Causes and symptoms

Fevers are primarily caused by viral or bacterial infections, such as pneumonia or influenza. However, other conditions can induce a fever, including allergic reactions; autoimmune diseases; trauma, such as breaking a bone; cancer ; excessive exposure to the sun; intense exercise; hormonal imbalances; certain drugs; and damage to the hypothalamus. When an infection occurs, fever-inducing agents called pyrogens are released, either by the body's immune system or by the invading cells themselves, that trigger the resetting of the thermostat. In other circumstances, the immune system may overreact (allergic reactions) or become damaged (autoimmune diseases), causing the uncontrolled release of pyrogens. A stroke or tumor can damage the hypothalamus, causing the body's thermostat to malfunction. Excessive exposure to the sun or intensely exercising in hot weather can result in heat stroke, a condition in which the body's cooling mechanisms fail. Malignant hyperthermia is a rare, inherited condition in which a person develops a very high fever when given certain anesthetics or muscle relaxants in preparation for surgery.

How long a fever lasts and how high it may go depends on several factors, including its cause, the age of the patient, and his or her overall health. Most fevers caused by infections are acute, appearing suddenly and then dissipating as the immune system defeats the infectious agent. An infectious fever may also rise and fall throughout the day, reaching its peek in the late afternoon or early evening. A low-grade fever that lasts for several weeks is associated with autoimmune diseases such as lupus or with some cancers, particularly leukemia and lymphoma.

Diagnosis

A fever is usually diagnosed using a thermometer. A variety of different thermometers are available, including traditional glass and mercury ones used for oral or rectal temperature readings and more sophisticated electronic ones that can be inserted in the ear to quickly register the body's temperature. For adults and older children, temperature readings are usually taken orally. Younger children who cannot or will not hold a thermometer in their mouths can have their temperature taken by placing an oral thermometer under their armpit. Infants generally have their temperature taken rectally using a rectal thermometer.

As important as registering a patient's temperature is determining the underlying cause of the fever. The presence or absence of accompanying symptoms, a patient's medical history, and information about what he or she may have ingested, any recent trips taken, or possible exposures to illness help the physician make a diagnosis. Blood tests can aid in identifying an infectious agent by detecting the presence of antibodies against it or providing samples for growth of the organism in a culture. Blood tests can also provide the doctor with white blood cell counts. Ultrasound tests, magnetic resonance imaging (MRI) tests, or computed tomography (CT) scans may be ordered if the doctor cannot readily determine the cause of a fever.

Treatment

Physicians agree that the most effective treatment for a fever is to address its underlying cause, such as through the administration of antibiotics. Also, because a fever helps the immune system fight infection, it usually should be allowed to run its course. Drugs to lower fever (antipyretics) can be given if a patient (particularly a child) is uncomfortable. These include aspirin, acetaminophen (Tylenol), and ibuprofin (Advil). Aspirin, however, should not be given to a child or adolescent with a fever since this drug has been linked to an increased risk of Reye's syndrome. Bathing a patient in cool water can also help alleviate a high fever.

A fever requires emergency treatment under the following circumstances:

  • newborn (three months or younger) with a fever over 100.5 °F (38 °C)
  • infant or child with a fever over 103 °F (39.4 °C)
  • fever accompanied by severe headache, neck stiffness, mental confusion, or severe swelling of the throat

A very high fever in a small child can trigger seizures (febrile seizures) and therefore should be treated immediately. A fever accompanied by the above symptoms can indicate the presence of a serious infection, such as meningitis, and should be brought to the immediate attention of a physician.

Prognosis

Most fevers caused by infection end as soon as the immune system rids the body of the pathogen and do not produce any lasting effects. The prognosis for fevers associated with more chronic conditions, such as autoimmune disease, depends upon the overall outcome of the disorder.

Resources

BOOKS

Gelfand, Jeffrey. "Fever, Including Fever of Unknown Origin." In Harrison's Principles of Internal Medicine, edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.

KEY TERMS

Antipyretic A drug that lowers fever, like aspirin or acetaminophen.

Autoimmune disease Condition in which a person's immune system attacks the body's own cells, causing tissue destruction.

Febrile seizure Convulsions brought on by fever.

Malignant hyperthermia A rare, inherited condition in which a person develops a very high fever when given certain anesthetics or muscle relaxants in preparation for surgery.

Meningitis A potentially fatal inflammation of the thin membrane covering the brain and spinal cord.

Metabolism The chemical process by which the body turns food into energy, which can be given off as heat.

Pyrogen A chemical circulating in the blood that causes a rise in body temperature.

Reye's syndrome A disorder principally affecting the liver and brain, marked by the rapid development of life-threatening neurological symptoms.

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Travers, Bridget. "Fever." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

Travers, Bridget. "Fever." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1G2-3451600638.html

Travers, Bridget. "Fever." Gale Encyclopedia of Medicine, 3rd ed.. 2006. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3451600638.html

Fever

Fever

Description

Normal body temperature varies somewhat from one individual to another but displays a general range and pattern around the "normal" temperature of 98.6°F. Early morning body temperature may be as low as 97°F, and as high as 99.3°F in the afternoon hours yet still be considered normal. Higher temperatures may be observed in healthy people, but an abnormal elevation (pyrexia) is classified as hyperthermia , or fever. Fever results from a failure in the body's ability to regulate and dissipate heat. Any fever presents an unpleasant and uncomfortable state for the patient. Fever may cause the patient to experience fatigue , chills, sweats, nausea, andin some caseslife-threatening conditions. When fevers occur in the elderly or the very young, the effects can be more harmful than in individuals who fall between those two age groups. The elderly may experience poor blood circulation, heart failure, an irregular heartbeat, or mental episodes. Children may lapse into fever-induced seizures. It is possible to treat fever with lukewarm sponge baths or bathing, removing excess clothing or bedding, and increasing the patient's fluid intake; however an important treatment is medication that lowers the body temperature to its normal range.

Causes

Fever associated with cancer can generally be categorized into four major causal groups: infection, tumors, allergic reactions to a drug, or allergic reaction to blood components in transfusion therapies. For cancer patients, fever should be considered a result of infection until an alternative cause is diagnosed. When a fever develops in a cancer patient, the individual must be thoroughly examined to determine the cause. A comprehensive physical examination should be administered by the physician and blood drawn for laboratory analysis.

Once a diagnosis has been made and treatment initiated, it is important to address problems created by the fever itself. It may be necessary to increase fluids and nutritional supplements. Because fever places increased demands on the body, this can be critical in restoring normal health for patients who may already be nutritionally compromised. Fever in a patient with neutropenia (low white blood cell count) represents the potential for a critical, life-threatening situation, and treatment should begin as quickly as the patient can reach the emergency room.

Physicians do not fully understand how tumors can cause fever, but certain correlations are well documented. Fever spikes may indicate that a tumor has grown or spread to other areas of the body, or that the tumor has produced some type of blockage. The fever associated with a tumor tends to be cyclic, and subsides with tumor treatment and recurs when the tumor returns or increases in size. In the case of drug-associated fever, the fever is an allergic-type reaction to a particular medication or combination of medications. Similarly, an immune response to donor blood cells is the typical cause of fever associated with blood components.

Treatments

Each of the major causes for fever associated with cancer has recommended conventional treatment procedures. For infection-related fever, broad-spectrum antibiotics , given orally, rectally, or intravenously, are the principle method of control. Some antibiotics may be started before a definitive diagnosis is made to retard additional complications caused by the infection. Treatment typically is administered for five to seven days as long as the fever and infection show a positive response.

Fever from a tumor is best treated by treating the tumor itself. Supplemental treatment for the fever may include the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and acetaminophen. Aspirin should only be used in patients with no risk of bleeding problems. The allergic responses manifesting in drug-or blood-associated fever may be treated by various methods: antihista-mines and acetaminophen may be administered prior to drug therapy or blood transfusion therapy ; discontinuing the present drug and choosing alternate medication may be required; blood may require irradiation or removal of white blood cells from the donor blood.

Alternative and complementary therapies

Some patients are investigating and adhering to the use of alternative treatments and complementary therapies. These choices may include holistic healing or herbal medication, and therapy utilizing biofeedback, relaxation therapy, and imagery techniques. Patients maintain that these alternative and complementary therapies add a sense of control to their life during a period when they have little control over anything. No conclusive data exists on the effectiveness of the therapies used alone; however in conjunction with conventional methods of fever management, they do not appear to hinder therapy and may provide the patient increased goodwill and a positive outlook.

Resources

PERIODICALS

Kern, Winfried., et al. "Oral versus Intravenous Empirical Antimicrobial Therapy for Fever in Patients with Granulocytopenia Who Are Receiving Cancer Chemotherapy."

The New England Journal of Medicine 341, no. 5 (29 July 1999): 312-318

OTHER

Herbs for Relieving Cancer. InnerSelf 2000 Copyright. 21April 2001, 1 July 2001 <http://www.innerself.com>

Jane Taylor-Jones, M.S.

KEY TERMS

Acetaminophen

The generic name for a common nonprescription medication useful in the treatment of mild pain or fever.

Antibiotic

A drug that fights infection.

Antihistamine

A drug that counteracts allergic responses.

Biofeedback

A process by which a person learns to influence two kinds of physiologic responses: those that are not ordinarily under voluntary control; and those that are easily regulated but for which regulation has broken down because of trauma or disease.

Immune response

An alteration in the reactivity of the body's immune system in response to a foreign substance.

Neutropenia

Lowered blood cell counts, especially in white blood cells, chiefly the neutrophils that aid in fighting infection.

Nonsteroidal anti-inflammatory drugs (NSAIDs)

A family of anti-inflammatory drugs that work by inhibiting the production of prostaglandins (a group of compounds that affect diverse bodily processes).

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Taylor-Jones, Jane. "Fever." Gale Encyclopedia of Cancer. 2002. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

Taylor-Jones, Jane. "Fever." Gale Encyclopedia of Cancer. 2002. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1G2-3405200183.html

Taylor-Jones, Jane. "Fever." Gale Encyclopedia of Cancer. 2002. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1G2-3405200183.html

fever

fever a term derived from the Latin febris, refers to an elevation of body temperature due to disease or injury. Man is a homeotherm, meaning that body temperature is kept within narrow limits by complex control mechanisms. This is distinct from poikilotherms, such as reptiles and amphibians, whose body temperature is just above the ambient temperature, and varies with it. Measured in the mouth, body temperature is close to 37°C (98.6°F), and does not usually vary by more than 1.5°C, although a rise up to 40°C can occur transiently in strenuous muscular exercise. In excessive heat exposure, normal temperature regulation is defeated, resulting in heat stroke. In other circumstances any deviation from the norm in an upward direction constitutes fever. Fever, or pyrexia, refers to a rise of up to 40.5°C and hyperpyrexia to a greater rise. Above about 41.5°C a person loses orientation and may become unconscious.

In some diseases the word ‘fever’ is incorporated into the common names, such as in puerperal, scarlet, typhoid, and yellow fevers, indicating that a rise in termperature is associated with the condition. Before the advent of mass vaccination programmes those with infectious fevers were taken in to isolation hospitals, often called fever hospitals. The word ‘fever’ is sometimes used in other contexts, such as ‘fever pitch’, when an individual, group, or crowd (such as a football crowd) becomes over-excited or agitated.

The body has a complex mechanism for controlling temperature that balances heat production against heat loss. Heat is continually produced by metabolism of all body cells, to an extent that varies with the activity of glands and organs, and of the muscles (shivering is an effective way to increase heat production). Heat is lost by radiation and convection, particularly from exposed parts such as the face and hands, and by evaporation of sweat. The control of the balance between heat production and heat loss is centred in the brain, in the hypothalamus, which acts basically as a thermostat. Input signals from heat- and cold-sensitive receptors in the skin relay information to the hypothalamus (these receptors are extremely sensitive: the heat receptors are able to detect a rapid rise in temperature of 0.007°C, while the cold receptors can detect a rapid fall of 0.012°C) and the ‘thermostat’ also senses the temperature of the blood passing through. While the discomfort of the experience of hot and cold environments resides in the skin, it is the body's ‘core’ temperature that matters, as many processes within the body are disrupted if the core temperature changes. Thus if the blood temperature rises, then the output signals from the thermostat lead to vasodilation of blood vessels in the skin and to sweating, thus increasing heat loss. Or, if body temperature falls, then heat loss is curtailed by vasoconstriction of surface blood vessels, and heat production may be increased by shivering.

In fever the hypothalamic thermostat becomes set at a higher temperature. The normal blood temperature is therefore sensed as being too low, and temperature-raising mechanisms come into action, accounting for initial pallor and shivering. Conversely, when fever is abating the set temperature is lowered, and the warm skin and sweating represent heat loss mechanisms.

The commonest cause of fever is infection by viruses, bacteria, yeasts, or parasites. Substances are released by these organisms which are collectively called pyrogens (substances causing a rise in temperature — pyrexia). The pyrogens act upon white blood cells to produce further, endogenous, pyrogens; these latter can also be released from tumours, from the brain after injury or stroke, from blood clots, or in autoimmune disease. The endogenous pyrogens interact in the brain with prostaglandin synthetase, the enzyme necessary for synthesis of prostaglandins, which in turn are the main agents that alter the setting of the ‘thermostat’. This explains why taking aspirin can abolish fever, since it inhibits prostaglandin synthetase; it also explains why, in the absence of fever, aspirin has no effect on body temperature.

In general, it is the practice to use drugs to reduce fever, but this may reduce the effectiveness of macrophages (white cells) to engulf and destroy bacteria. Experimental evidence indicates that prevention of pyrexia is detrimental to survival in infected animals. It is equivocal whether or not fever can be universally regarded as a body defence mechanism, particularly as its usefulness or otherwise where there is no infection is obscure.

Alan W. Cuthbert


See also heat exposure; injury; prostaglandins; temperature regulation.

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COLIN BLAKEMORE and SHELIA JENNETT. "fever." The Oxford Companion to the Body. 2001. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

COLIN BLAKEMORE and SHELIA JENNETT. "fever." The Oxford Companion to the Body. 2001. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1O128-fever.html

COLIN BLAKEMORE and SHELIA JENNETT. "fever." The Oxford Companion to the Body. 2001. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O128-fever.html

fever

fever, elevation of body temperature above the normal level, which in humans is about 98°F (37°C) when measured orally. Fever is considered to be a symptom of a disorder rather than a disease in itself. Under normal conditions the heat that is generated by the burning of food by the body is dissipated through such processes as perspiration and breathing. It is believed that infectious diseases, injury to the body tissues, and other conditions that cause inflammation lead to the release of prostaglandins, a type of hormone, which bind to sites in the hypothalamus, the center of temperature control in the body. The rise in temperature that is triggered as a result acts as part of the body's defenses against infection; white blood cells become more active, and most bacteria do not thrive as well. The effects of fever on the body are weakness, exhaustion, and sometimes a depletion of body fluids through excessive perspiration. Extremely high fevers may cause convulsive reactions and eventual death. In addition to infectious diseases (such as pneumonia and tonsillitis), disorders of the brain, certain types of cancer, and severe heatstroke may cause fever. There are also cases of fever where the cause cannot be detected. Treatment includes increasing the intake of fluids and administering aspirin and other fever-reducing medications. Aspirin may be dangerous in fevers of children because of Reye's syndrome. However, primary treatment is directed at the underlying cause unless the fever is very high (above 104°F/40°C). Persons with such dangerously high fevers are sometimes sponged with cool water or immersed in cool baths.

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"fever." The Columbia Encyclopedia, 6th ed.. 2016. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

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Fever

Fever

How Is Body Temperature Controlled?

How Does Illness Cause Fever?

Who Gets Fever?

How Is Fever Diagnosed?

When Should a Doctor Be Consulted?

How Is Fever Treated?

How Can Fever Be Prevented?

Resource

Fever is an abnormally high body temperature that usually occurs during an infection, inflammation, or some other kind of illness. Fever is not a disease itself but it is one of the most common signs of illness, especially among children.

KEYWORDS

for searching the Internet and other reference sources

Body temperature

Febrile convulsion

Hyperthermia

Infection

Inflammation

Pyrexia

Ups and Downs

A persons temperature normally varies each day by about 1 degree F (0.6 degrees C). It is lowest in the early morning and highest in the late afternoon. This daily variation is called the circadian (sir-KADE-ee-an) rhythm. When a person has a fever, it usually follows the same daily pattern.

Other factors also can affect what is normal. In women of childbearing age, for instance, the early morning temperature usually goes up each month just before ovulation (ov-u-LA-shun), the release of an egg from the ovary. It stays elevated briefly and then returns to the lower level.

Fever of Unknown Origin

Sometimes a person has a fever that lasts for two or three weeks, and the doctor cannot find a cause, despite performing the usual array of medical tests. This condition is referred to as fever of unknown origin.

In about 90 percent of cases, a cause eventually is found. The most common causes are infectious diseases. Fever of unknown origin is particularly common in people infectedwith HIV, the human immunodeficiency virus that causes AIDS.

How Is Body Temperature Controlled?

The body adjusts its temperature in much the same way that the thermostat in a house works. With a thermostat, people set the temperature they want, and the heating or cooling system clicks on until the inside of the house reaches the right temperature. After that, the heater or air conditioner clicks on and off automatically to keep the temperature in the house hovering around the desired temperature.

The bodys thermostat is located in the hypothalamus (hy-po-THAL-a-mus), a small part of the brain that also helps control hunger, thirst, pleasure, and pain. The thermostat, called the thermoregulatory (ther-mo-REG-u-la-tor-ee) center, normally keeps the bodys temperature hovering around 98.6 degrees Fahrenheit (F) (37 degrees Centigrade).

Like a house, the body has sensors that tell the thermostat if the temperature inside is rising or falling. In the body, these sensors are cells located in the skin and in the brain itself. If the sensors report that the bodys temperature is rising, the bodys cooling system clicks on, telling the cells to burn less fuel and produce less heat. The blood vessels expand to let heat escape from the skin, sweat pours out to cool the body as it evaporates, and the brain may get a bright idea: Lets go into the shade and have a cold drink.

Fever

With fever, the thermostat in the brain is reset to a higher temperature. Instead of keeping the bodys temperature hovering around 98.6 degrees F, the bodys heating and cooling systems may keep the temperature at 100 to 102 degrees F or even higher.

Normal temperature varies a bit from person to person and from morning to evening, making it hard to state precisely where normal ends and fever begins. Many doctors, however, say that a temperature of more than 99 or 100 degrees F (37.2 or 37.8 degrees C) should be considered a fever. A temperature of 104 degrees F or higher could be considered a high fever.

Hyperthermia

Sometimes a persons temperature can rise for a different reason. Hyperthermia (hy-per-THER-me-a) occurs if the heat outside is too much for the bodys cooling system to handle, making body temperature rise. The most severe cases of hyperthermia tend to occur in people who can not sweat as much as normal, such as elderly people or those taking certain medications.

How Does Illness Cause Fever?

Bacteria and viruses themselves, as well as toxins (poisonous waste products) produced by some bacteria, cause fever. In some cases, they work directly on the brain to raise the thermostat. More commonly, they cause the bodys immune system* to produce proteins called cytokines (SY-to-kines). The cytokines help fight the infection, but they also reset the brains thermostat, causing fever.

* immune system
(im-YOON SIS-tem) is the body system made up of organs and cells that defend the body against infection or disease.

The Name Is Familiar

Many infectious diseases are named for the major symptom of fever. Most of those listed below lead to fevers of about 102 to 104 degrees F (39 to 40 degrees C). Dengue fever, Lassa fever, and yellow fever are caused by viruses. The others are caused by bacteria.

  • Dengue (DENG-e) fever causes sudden high fever, headache, extreme tiredness, severe joint and muscle pain, swollen lymph nodes, and a rash. It is spread by mosquitoes.
  • Lassa (LAH-sa) fever causes fever, headache, dry cough, back pain, vomiting, diarrhea, sore throat, and facial swelling. It is spread by rats and from person to person.
  • Q fever causes sudden high fever, severe headache, and chills. It is spread by farm animals and insects.
  • Rheumatic (roo-MAT-ik) fever causes painful, swollen joints, fever, and heart murmurs (abnormal heart sounds). It is caused by the same bacterium that causes strep throat.
  • Rat-bite fever causes sudden chills, fever, headache, vomiting, back pain, a rash on the hands and feet, and temporary arthritis (joint inflammation). It is spread by rats and mice.
  • Relapsing (re-LAPS-ing) fever causes sudden chills and high fever, fast heartbeat, severe headache, vomiting, muscle pain, and sometimes mental confusion. Symptoms can recur several times. It is spread by ticks and lice.
  • Rocky Mountain spotted fever causes fever, headache, skin ulcers (open sores), and a rash. It is spread by ticks.
  • Scarlet fever causes high fever, sore throat, flushed cheeks, and a rash, especially in children. It is caused by the same bacterium that causes strep throat.
  • Typhoid (TY-foid) fever causes fever along with abdominal pain, headache, and extreme fatigue. It is spread by food and water that contain Salmonella bacteria.
  • Yellow fever causes sudden fever, slow pulse, nausea, vomiting, constipation, muscle pains, liver failure, and severe fatigue. It is spread by mosquitoes.

Any substance that causes fever is called a pyrogen (PY-ro-jen), from the Greek word for fire-causer. If the substance comes from outside the body, such as a toxin from bacteria, it is called an exogenous (ek-SOJ-e-nus) pyrogen. The prefix exo- means outside in Greek. If the substance comes from inside the body, such as a cytokine, it is called an endogenous (en-DOJ-e-nus) pyrogen. The prefix endo- means inside in Greek.

Sometimes the immune system produces pyrogens even without an infection. For instance, this may happen if a person:

  • has an autoimmune disease*, such as rheumatoid arthritis or lupus
  • has inflammation* anywhere in the body
  • has cancer, such as leukemia or lymphoma
  • was a given a blood transfusion* that is not compatible with the persons own blood type
  • has a reaction to a medication
* autoimmune disease
(aw-to-i-MYOON disease) is a disease resulting from an immune system reaction against the bodys own tissues or proteins.
* inflammation
(in-fla-MAY-shun) is an immune system reaction to an injury irritation, or infection. It often includes swelling, pain, warmth, and redness.
* transfusion
(trans-FYOO-zhun) is the transfer of blood or blood products directly into a persons bloodstream.

People sometimes say that fever is a sign that the immune system is active, working to protect the body from illness. That may be true in some cases, but it is not always so. People often get fevers, for instance, if their immune system is weak or damaged. In reality, scientists are not sure exactly what, if anything, fever indicates about the state of the immune system.

Who Gets Fever?

Fever is caused by so many common illnesses, including colds and flu, that it happens to everyone many times in the course of a lifetime. Young children are particularly likely to get bacterial and viral infections that cause fever, such as strep throat and ear infections. Sometimes minor viral infections cause high fevers in children, while illnesses that are more serious cause milder fevers. People of all ages get fever.

Helpful fever

There is some evidence that fever can make the immune system more effective and weaken certain bacteria. However, most of this evidence comes from animals or experiments on human cells in test tubes. Scientists really do not know whether fever helps people fight off infections in real life. It could turn out that fever helps in certain cases but not in others.

Fever often can help in another way, however. It can be an important sign that a person is sick. Its movements up and down can indicate whether a person is getting better or worse.

Harmful fever

Fever often makes an illness more unpleasant. In addition, a feverish body needs more oxygen, which means that the heart and lungs have to work harder as the fever rises. This can be a problem for people who already have heart or lung problems.

Fever can make mental problems worse for elderly people who have dementia (de-MEN-sha), which is a form of mental confusion and loss of memory that can develop gradually as people age. High fever also can cause temporary mental confusion, called delirium (de-LEER-e-um), even in healthy people.

Febrile convulsion

Children under age 5 can have a different problem if their temperature rises quickly. They may experience a kind of seizure called a febrile convulsion (FEB-ryl kon-VUL-shun). Their muscles may twitch, and they may lose consciousness for several minutes. Usually, a febrile convulsion needs no treatment and may not recur. However, febrile convulsions can be very upsetting and frightening. They also can lead to injury; for example, if a child falls.

Extremely high temperatures of around 107 degrees F or higher can do permanent brain damage at any age if they last for a long time. Temperatures that high usually are caused by hyperthermia, not by fever from an illness.

How Is Fever Diagnosed?

People with a fever often feel hot, tired, achy, and generally sick. They sometimes have shaking chills as their temperature rises. Shaking helps raise the temperature to the feverish level set by the bodys thermostat. They may sweat heavily when the fever breaks (starts to go away) or if it falls temporarily as part of an up-and-down pattern. Sweating helps lower the temperature to the new, lower point set by the thermostat.

Although the classic way of checking for fever at home is to touch the persons forehead to see how warm it feels, this often does not work. The only way to tell for sure if a person has a fever is by taking the temperature with a thermometer. Three kinds of thermometers can be used: digital, mercury, or tympanic.

Digital thermometers, usually used in medical offices and hospitals as well as at home, are electronic. They can take an oral temperature when placed under the tongue, a rectal temperature when placed into the rectum, or an axillary (AK-si-lar-y) temperature when placed in the armpit. In general, rectal temperatures are about 1 degree F higher than oral ones.

Mercury thermometers, which used to be the only kind available, are made out of glass and contain liquid mercury. They come in oral or rectal versions. Either kind can be used in the armpit as well. They are cheaper than digital thermometers, but they take longer to use.

Tympanic (tim-PAN-ik) thermometers are a special kind of digital thermometer that is placed into the ear. While the other thermometers take several minutes to give a reading, the tympanic thermometer takes only a few seconds. However, tympanic thermometers are more expensive and can be inaccurate if placed improperly in the ear.

When Should a Doctor Be Consulted?

A doctor should be consulted if a fever is high, lasts longer than a few days, or is accompanied by other symptoms, such as a rash; pain in the joints, neck, or ears; unusual sleepiness; or a dazed or very sick feeling. For babies under about 3 months old, a doctor should be consulted about any fever.

Fiery Language

Many medical terms dealing with fever start with the prefix pyro- or pyr-, from the Greek word for fire. Fever itself is called pyrexia (pi-RECKS-ee-a). Substances that cause fever are called pyrogens, and medicines that reduce fever are called antipyretics.

The same Greek root has given rise to words outside medicine. A funeral pyre is a consuming blaze used to cremate (turn to ashes) a body. Pyromania is a compulsion to set fires. Pyrotechnics are fireworks. Pyrex is the trade name for a kind of glass used in baking pans because it can withstand high heat.

The doctor will try to find and treat the underlying cause of the fever. Antibiotics can cure many bacterial infections, such as those that cause many earaches and sore throats. There are no medications to treat most viral infections.

How Is Fever Treated?

In a basically healthy adult or older child, there usually is no medical reason to treat the fever itself unless it is very high. In fact, lowering the fever with drugs can make it harder to tell if a person is actually getting better or if the drugs are just keeping the fever down. In younger children, though, doctors often treat fevers of 100 or 101 degrees F, in part to avoid febrile convulsions. Of course, if a person of any age is very uncomfortable or unable to sleep, even a low fever can be treated to provide relief.

Fever can be lowered by drugs called antipyretics (an-ti-py-RET-iks) that do not require prescriptions. The major ones are acetaminophen (a-seet-a-MIN-oh-fen), Ibuprofen (i-byoo-PRO-fen), and aspirin. However, aspirin should not be given to children with a fever. If children have a viral illness, such as influenza or chickenpox, aspirin makes it likelier that they may get a rare but dangerous illness called Reyes syndrome*. This does not happen with acetaminophen or Ibuprofen.

* Reyes syndrome
(RYZESIN-drome) is a rare and sometimes fatal disease that causes vomiting, confusion, and coma. It occurs mainly in children, usually after a viral infection such as influenza or chickenpox.

Antipyretic medicines are available in pills for adults, chewable tablets for children, and liquid drops for babies. Acetaminophen also comes in suppositories (su-POZ-i-tor-eez), waxy pellets that are inserted into the rectum. They are used for people who cannot take medicine by mouth for some reason.

A lukewarm bath also can help lower a high temperature. However, cold water or alcohol rubs can do more harm than good by causing the body to shiver, which just raises body temperature more. In addition to these treatments, it is important for a person with a fever to drink plenty of liquids to avoid dehydration*. In extreme cases, a person in the hospital with a very high fever may be wrapped in a special cooling blanket or immersed in ice water.

* dehydration
(de-hy-DRAY-shun) is a condition caused by the loss of fluids from the body faster than they can be replaced. Babies, small children, and the elderly may become dehydrated faster than older children and adults.

How Can Fever Be Prevented?

Many of the diseases that cause fever can be prevented by vaccination*. These include influenza, measles, mumps, rubella (German measles), chickenpox, diphtheria, and typhoid fever. A number of other diseases that cause widespread fever in poorer nations are prevented in the United States by good sanitation systems and access to clean water. Still other diseases, such as colds and strep infections, often can be prevented by washing the hands properly before eating and, if possible, by avoiding contact with people who already have those infections.

* vaccination
(vak-si-NAY-shun) means giving a person a vaccine to protect against a particular disease. A vaccine is a preparation of a weakened or killed germ or of part of the germs structure. It stimulates the immune system to fight the germ but does not cause infection itself.

See also

Bacterial Infections

Dengue Fever

Diphtheria

German Measles (Rubella)

Heat-Related Injuries

Infection

Influenza

Lassa Fever

Mumps

Reye’s Syndrome

Rheumatic Fever

Rocky Mountain Spotted Fever

Scarlet Fever

Seizures

Strep Throat

Typhoid Fever

Yellow Fever

Viral Infections

Resource

American College of Emergency Physicians, P.O. Box 619911, Dallas, TX 75261-9911. An organization of physicians that provides information about fever on its website. http://www.acep.org

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fever

fever (pyrexia) (fee-ver) n. a rise in body temperature above the normal, i.e. above an oral temperature of 98.6°F (37°C) or a rectal temperature of 99°F (37.2°C), usually caused by bacterial or viral infection. Fever is generally accompanied by shivering, headache, nausea, constipation, or diarrhoea. intermittent f. a periodic rise and fall in body temperature, as in malaria. remittent f. a fever in which body temperature fluctuates but does not return to normal. See also relapsing fever.

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fever

fe·ver / ˈfēvər/ • n. an abnormally high body temperature, usually accompanied by shivering, headache, and in severe instances, delirium. ∎  a state of nervous excitement or agitation: I was mystified, and in a fever of expectation. ∎  the excitement felt by a group of people about a particular public event: election fever reaches its climax tomorrow.

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fever

fever OE. fēfor m., corr. to MLG. feber, OHG. fiebar m. (G. fieber) — L. febris fem., of obscure orig. Reinforced in ME. from AN. fevre, (O)F. fièvre :- L. febris.
Hence feverish XIV.

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T. F. HOAD. "fever." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

T. F. HOAD. "fever." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 26, 2016). http://www.encyclopedia.com/doc/1O27-fever.html

T. F. HOAD. "fever." The Concise Oxford Dictionary of English Etymology. 1996. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O27-fever.html

fever

fever Elevation of the body temperature above normal, that is 37°C (98.6°F). It is mostly caused by bacterial or viral infection and can accompany virtually any infectious disease.

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"fever." World Encyclopedia. 2005. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O142-fever.html

fever

fevercadaver, slaver •halva, salver, salvor •balaclava, Bratislava, carver, cassava, Costa Brava, guava, Java, kava, larva, lava, palaver •woodcarver •clever, endeavour (US endeavor), ever, forever, however, howsoever, never, never-never, sever, Trevor, whatever, whatsoever, whenever, whensoever, wheresoever, wherever, whichever, whichsoever, whoever, whomever, whomsoever, whosoever •delver, elver •Denver •Ava, caver, craver, deva, engraver, enslaver, favour (US favor), flavour (US flavor), graver, haver, laver, paver, quaver, raver, saver, savour (US savor), shaver, vena cava, waiver, waver •lifesaver • semiquaver •achiever, beaver, believer, cleaver, deceiver, diva, Eva, fever, Geneva, griever, heaver, leaver, lever, Neva, perceiver, receiver, reiver, reliever, retriever, Shiva, underachiever, viva, weaver, weever •cantilever

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"fever." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 26 May. 2016 <http://www.encyclopedia.com>.

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"fever." Oxford Dictionary of Rhymes. 2007. Retrieved May 26, 2016 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O233-fever.html

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