Fever
Labels Fever
- Definition .
- 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?
Showing posts with label Fever. Show all posts
Showing posts with label Fever. Show all posts
Labels Fever
Definition
Fever is an abnormally elevated 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.
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.
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 body’s thermostat is located in the hypothalamus (hy-po-THALa-
mus), a small part of the brain that also helps to regulate hunger, thirst,
awareness of pleasure, and awareness of pain. The thermostat region of the
hypothalamus, called the thermoregulatory (ther-mo-REG-u-la-tor-ee)
center, normally keeps the body’s temperature hovering at around 98.6
degrees Fahrenheit (F) (36.8 degrees Centigrade [C]).
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
body’s temperature is rising, the body’s 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 (the evaporating sweat draws heat away
from blood vessels), sweat pours out to cool the body as it evaporates,
and the brain may get a bright idea: “Let’s 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 body’s temperature hovering at around
98.6 degrees F, the body’s 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. In fact, temperature measured at different places in the
body can also be different. Temperature measured at the mouth can be
one whole degree Fahrenheit lower than the actual core body temperature.
For this reason, core body temperature is best measured at the rectum
or at the ear. Most doctors say that a core body temperature at or above
100.4 degrees F (38 degrees C) should be considered a fever. Core body
temperature above 104 degrees F (40 degrees C) is generally considered a
high fever.
Hyperthermia
Sometimes a person’s temperature can rise for a different
reason. Hyperthermia (hy-per-THER-me-a), quite different from fever,
occurs when the heat outside is too much for the body’s cooling system to
handle, making body temperature (and the set point) rise. The most severe
cases of hyperthermia tend to occur in people who cannot sweat as much
as others, such as elderly people or those taking certain medications.
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 body’s thermostat is located in the hypothalamus (hy-po-THALa-
mus), a small part of the brain that also helps to regulate hunger, thirst,
awareness of pleasure, and awareness of pain. The thermostat region of the
hypothalamus, called the thermoregulatory (ther-mo-REG-u-la-tor-ee)
center, normally keeps the body’s temperature hovering at around 98.6
degrees Fahrenheit (F) (36.8 degrees Centigrade [C]).
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
body’s temperature is rising, the body’s 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 (the evaporating sweat draws heat away
from blood vessels), sweat pours out to cool the body as it evaporates,
and the brain may get a bright idea: “Let’s 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 body’s temperature hovering at around
98.6 degrees F, the body’s 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. In fact, temperature measured at different places in the
body can also be different. Temperature measured at the mouth can be
one whole degree Fahrenheit lower than the actual core body temperature.
For this reason, core body temperature is best measured at the rectum
or at the ear. Most doctors say that a core body temperature at or above
100.4 degrees F (38 degrees C) should be considered a fever. Core body
temperature above 104 degrees F (40 degrees C) is generally considered a
high fever.
Hyperthermia
Sometimes a person’s temperature can rise for a different
reason. Hyperthermia (hy-per-THER-me-a), quite different from fever,
occurs when the heat outside is too much for the body’s cooling system to
handle, making body temperature (and the set point) rise. The most severe
cases of hyperthermia tend to occur in people who cannot sweat as much
as others, 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 body’s immune system to produce proteins called cytokines (SY-tokines).
The cytokines help fight the infection, but they also reset the
brain’s thermostat, causing fever.
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-enus)
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 the following:
produced by some bacteria, cause fever. In some cases, they work
directly on the brain to raise the thermostat. More commonly, they cause
the body’s immune system to produce proteins called cytokines (SY-tokines).
The cytokines help fight the infection, but they also reset the
brain’s thermostat, causing fever.
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-enus)
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 the following:
- an autoimmune disease, such as rheumatoid arthritis or lupus
- inflammation anywhere in the body
- cancer, such as leukemia or lymphoma
- received a blood transfusion* that is not compatible with his or her
own blood type - has a reaction to a medication
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, such
as strep throat and ear infections, that cause fever. Sometimes minor viral
infections cause high fevers in children, whereas illnesses that are more
serious cause milder fevers. People of all ages get fever.
Helpful fever
Some evidence suggests that an elevated body temperature
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 actually helps people fight off infections. It may be that fever helps
in certain cases but not in others.
Fever often can be helpful in another way. It can be an important sign
that a person is sick. The movements of temperature 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, which 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 five years of age 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 frightening. They also can lead
to injury; for example, if a child falls.
Extremely high temperatures of around 107 degrees F or higher can
cause permanent brain damage at any age if they last for a long time.
Temperatures that high usually result from hyperthermia, not from an
illness-related fever.
that it happens to everyone many times in the course of a lifetime. Young
children are particularly likely to get bacterial and viral infections, such
as strep throat and ear infections, that cause fever. Sometimes minor viral
infections cause high fevers in children, whereas illnesses that are more
serious cause milder fevers. People of all ages get fever.
Helpful fever
Some evidence suggests that an elevated body temperature
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 actually helps people fight off infections. It may be that fever helps
in certain cases but not in others.
Fever often can be helpful in another way. It can be an important sign
that a person is sick. The movements of temperature 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, which 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 five years of age 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 frightening. They also can lead
to injury; for example, if a child falls.
Extremely high temperatures of around 107 degrees F or higher can
cause permanent brain damage at any age if they last for a long time.
Temperatures that high usually result from hyperthermia, not from an
illness-related fever.
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 that has been set by the body’s
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
person’s forehead to see how warm it feels, doing so 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 are available:
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. The measured rectal temperature is the closest to what
the core of the body actually feels and thus is considered to be the most
accurate.
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.
sometimes have shaking chills as their temperature rises. Shaking helps
raise the temperature to the feverish level that has been set by the body’s
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
person’s forehead to see how warm it feels, doing so 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 are available:
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. The measured rectal temperature is the closest to what
the core of the body actually feels and thus is considered to be the most
accurate.
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 three months of age, a doctor should be consulted
about any fever.
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. No medications are available to treat
most viral infections.
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 three months of age, a doctor should be consulted
about any fever.
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. No medications are available 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 above 100 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, and aspirin. However, aspirin should
not be given to children or teenagers 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 Reye’s syndrome. This possibility
does not exist with their taking acetaminophen or ibuprofen.
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 whatever reason.
A lukewarm bath can also 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.
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 above 100 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, and aspirin. However, aspirin should
not be given to children or teenagers 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 Reye’s syndrome. This possibility
does not exist with their taking acetaminophen or ibuprofen.
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 whatever reason.
A lukewarm bath can also 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.
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 have been eradicated 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 these infections.
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 have been eradicated 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 these infections.
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