Chills is a feeling of coldness occurring during a high
fever
Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
, but sometimes is also a common
symptom which occurs alone in specific people. It occurs during fever due to the release of
cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrin ...
s and
prostaglandins as part of the
inflammatory response
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molecu ...
, which increases the
set point for body temperature in the
hypothalamus
The hypothalamus () is a part of the brain that contains a number of small nuclei with a variety of functions. One of the most important functions is to link the nervous system to the endocrine system via the pituitary gland. The hypothalamu ...
. The increased set point causes the body
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer.
Thermometers are calibrated in various Conversion of units of temperature, temp ...
to rise (
pyrexia
Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
), but also makes the patient feel cold or chills until the new set point is reached.
Shivering
Shivering (also called shuddering) is a bodily function in response to cold and extreme fear in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Skeletal muscles begin to sh ...
also occurs along with chills because the patient's body produces heat during muscle contraction in a physiological attempt to increase body temperature to the new set point. When it does not accompany a high fever, it is normally a light chill.
Sometimes a chill of medium power and short duration may occur during a scare, especially in scares of fear, commonly interpreted like or confused by
trembling
A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the hands, arms, eyes, f ...
.
Severe chills with violent shivering are called rigors.
Causes
Chills are commonly caused by inflammatory diseases, such as
influenza. It is also common in urinary tract infections.
Malaria
Malaria is a mosquito-borne infectious disease that affects humans and other animals. Malaria causes symptoms that typically include fever, tiredness, vomiting, and headaches. In severe cases, it can cause jaundice, seizures, coma, or death. S ...
is one of the common reasons for chills and rigors. In malaria, the
parasites
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson ha ...
enter the
liver
The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
, grow there and then attack the red blood cells which causes rupture of these cells and release of a toxic substance
hemozoin
Haemozoin is a disposal product formed from the digestion of blood by some blood-feeding parasites. These hematophagous organisms such as malaria parasites (''Plasmodium spp.''), ''Rhodnius'' and ''Schistosoma'' digest haemoglobin and release high ...
which causes chills recurring every 3 to 4 days. Sometimes they happen in specific people almost all the time, in a slight power, or it less commonly happens in a generally healthy person.
See also
*
Cold chill
Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute thermodynamic ...
*
Goose bumps
Goose bumps, goosebumps or goose-pimples are the bumps on a person's skin at the base of body hairs which may involuntarily develop when a person is tickled, cold or experiencing strong emotions such as fear, euphoria or sexual arousal.
The ...
*
Night sweats
Night sweats, also referred to as nocturnal hyperhidrosis (Hyperhidrosis - a medical term for excessive sweating + nocturnal - night), is the repeated occurrence of excessive sweating during sleep
Sleep is a sedentary state of mind and bo ...
References
External links
{{General symptoms and signs
Symptoms and signs
Cold
Thermoregulation
fr:Frissonnement