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Febrile intoxication syndrome

 
, medical expert
Last reviewed: 04.07.2025
 
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Feverish-intoxication syndrome is a symptom complex that characterizes the non-specific adaptive response of a macroorganism to microbial aggression. The degree of expression of feverish-intoxication syndrome is a universal criterion for assessing the severity of the infectious process. The concept of "feverish-intoxication syndrome" includes fever, myasthenia, symptoms of damage to the central nervous system and the autonomic nervous system, and the cardiovascular system.

The term "febrile intoxication syndrome" does not include manifestations of intoxication caused by organ damage and organ failure (renal, hepatic, cardiac), and symptoms caused by the specific action of microbial toxins, in particular myasthenia in botulism, convulsions in tetanus, diarrhea in cholera, cellular edema in diphtheria. Febrile intoxication syndrome is classified according to the severity of its individual components. In this case, the severity is determined by the most pronounced symptoms.

The presented classification allows us to assess the severity of the patient's condition, but does not exclude variants of the condition of a specific patient that do not fit into this scheme.

If a patient with criteria corresponding to a mild degree of intoxication has lethargy or severe arterial hypotension, then the intoxication and the patient's condition should be considered severe.

If individual criteria of intoxication do not correspond to the others, the corresponding organ pathology should be excluded, for example: intense headache with nausea and vomiting, disturbances of consciousness, convulsions allow us to think about neuroinfection, tachycardia, arterial hypotension - about heart damage, nausea, vomiting, anorexia - about damage to the digestive tract, high fever with a mild degree of intoxication requires exclusion of non-infectious etiology of the disease. The severity of the febrile-intoxication syndrome varies significantly in individual infectious diseases. In brucellosis, high fever often occurs without significant intoxication and patients can maintain their ability to work at a body temperature of 39.0 ° C and above. In severe infectious mononucleosis, severe myasthenia dominates with weak expression of other manifestations of intoxication.

Classification of febrile intoxication syndrome

Degree of expression

Main symptoms

Light

Medium degree

Heavy

Very heavy

Fever

Up to 38.0 °C

38.1-39.0 °C

39.1-40.0 °C

Over 40.0 °C

Weakness (myasthenia)

Fatigue

Limitation of mobility

Lying position

Lying position. Difficulty with active movements.

Algia (pain in muscles, joints, bones)

Weak, absent

Moderate

Strong

Strong, may be absent

Chills

-

Chilliness, shivering

Expressed

Amazing

Headache

Weak

Moderate

Strong

Strong, may be absent

Nausea

-

Possible

Often

Possible

Vomit

-

-

Possible

Often

Meningeal syndrome

-

-

Possible

Often

Disturbances of consciousness

-

-

Stupor, stupor

Stupor, coma

Cramps

-

-

Possible

Possible

Delirium, delirium

-

-

Possible

Often

Heart rate, beats per minute

Up to 80

81-90

91-110

Over 110 (bradycardia possible)

BP, mmHg

Norm

Lower limit of normal

80/50-90/60

Less than 80/50

Decreased appetite

Maybe

Constantly

Anorexia

Anorexia

Sleep disturbance

Maybe

Often

Insomnia, drowsiness

Insomnia. drowsiness

The main manifestation of febrile-intoxication syndrome is fever. In infectious diseases, it is caused by the effect on the hypothalamic thermoregulation centers of exogenous (microbial) and endogenous pyrogens formed by granulocytes and macrophages or accumulating in inflammatory foci. Fever is assessed by the following parameters: the severity of the development of the febrile reaction, the height of the rise in body temperature, the duration of fever, the rate of decrease in body temperature, the type of temperature curve.

If the body temperature rises to its maximum values within 1-2 days, its increase is considered acute, within 3-5 days - subacute, more than 5 days - gradual. Fever up to 38 °C is considered subfebrile (up to 37.5 °C - low subfebrile, 37.6-38.0 °C - high subfebrile). Fever within the range from 38.1 to 41.0 °C is designated as febrile (up to 39.0 °C - moderate, from 39.1 to 41.0 °C - high), over 41.0 °C - hyperpyretic. Fever lasting up to 5 days is considered short-term, 6-15 days - long-term, over 15 days - protracted. A decrease in body temperature from a febrile or hyperpyretic level to normal within 24 hours is designated as critical, or a crisis; within 48-72 hours - as accelerated lysis; more gradual - as lysis.

Depending on the daily fluctuations and the type of temperature curve, several types of temperature curves are distinguished.

A constant curve with daily fluctuations within 1 °C; body temperature exceeds 39 °C. Typical for severe forms of typhoid and typhus.

Remittent (weakening) fever is characterized by daily fluctuations from 1.0 to 3.0 °C. It is observed in many infectious diseases.

With hectic fever, daily fluctuations in body temperature are 3.0-5.0 °C. As a rule, an increase in temperature is accompanied by chills, and a decrease by profuse sweating. It is observed in sepsis, severe purulent inflammatory processes.

Intermittent fever is characterized by febrile attacks that last up to a day and alternate with fever-free days. Typical of malaria.

In relapsing fever, periods of elevated temperature last for several days and are followed by several days of normal temperature, after which the fever resumes. It is observed in relapsing fevers. In many infections, repeated increases in temperature are caused by complications (flu) or a relapse of the disease (typhoid fever).

In the case of protracted infectious diseases, a wave-like fever is observed, when periods of elevated body temperature alternate with periods of subfebrile temperature. Currently, it is rarely encountered in infectious diseases. In bacterial infections, a repeated wave of fever may be associated with the ineffectiveness of etiotropic therapy.

Fever of an irregular type is common , when the temperature curve has an irregular appearance. In severe septic processes, perverted fever is possible, in which the morning temperature exceeds the evening temperature.

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Causes of febrile intoxication syndrome

Fever accompanied by intoxication is typical for most bacterial, viral and protozoal infectious diseases, generalized mycoses. It is possible with helminthic invasions (opisthorchiasis, trichinosis, schistosomiasis). Fever-intoxication syndrome is not typical for cholera, botulism, viral hepatitis B and viral hepatitis C, uncomplicated amoebiasis, cutaneous leishmaniasis, giardiasis, localized mycoses and many helminthic invasions.

The level of fever generally reflects the severity of the disease. Fever may be absent or subfebrile in mild cases of many diarrheal and acute respiratory infections.

What causes febrile intoxication syndrome?

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Treatment of febrile intoxication syndrome

Treatment is aimed at detoxification and reducing excessive temperature reaction. In case of mild intoxication and subfebrile fever, home regimen is recommended, exclusion of hot spices, fried foods, smoked foods, canned food, plenty of fluids (tea, juices, fruit drinks, mineral water, rosehip decoction, compote - up to 3 liters per day).

In case of moderate intoxication and moderate fever, bed rest is indicated, hospitalization according to individual indications in some cases (fever over 5 days, aggravated premorbid background), the same diet as in case of mild intoxication with the exclusion of refractory fats, plenty of fluids with the inclusion of diaphoretics - honey, raspberries, lingonberries, ascorbic acid. In case of poor subjective tolerance of fever - antipyretics: acetylsalicylic acid, paracetamol, metamizole sodium, cold on the forehead.

Treatment of febrile intoxication syndrome

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