What is considered a fever?

Introduction

Fever is a common physiological response characterized by an elevation in body temperature. It is often associated with various diseases and conditions, both infectious and non-infectious. Understanding what constitutes a fever and its underlying mechanisms is crucial for accurate diagnosis and treatment.

Key Insights

Definition of Fever:
- Fever is generally defined as a body temperature of at least 38°C (100.4°F) .
- It is a rise in core body temperature measured at the tympanic membrane, greater than 37.8°C, which is one standard deviation beyond the upper limit of the normal range.
Mechanisms and Causes:
- Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 (PGE2) in the preoptic area of the hypothalamus, raising the body's temperature set point.
- It is a complex, coordinated autonomic, neuroendocrine, and behavioral response orchestrated largely by the hypothalamus .
- Fever can be triggered by a wide variety of infectious organisms and non-infectious inflammatory conditions .
Physiological and Evolutionary Aspects:
- Fever is a regulated resetting of body temperature, not a failure of control, and has a long evolutionary history, suggesting its beneficial effects.
- It is part of the acute-phase reaction to immune challenges and involves the coordination of multiple physiological, endocrinologic, and immunologic systems .
Clinical Considerations:
- Normal body temperature for a healthy adult is around 98.6°F (37°C), but it varies throughout the day and in response to certain conditions like physical activity or hot weather.
- Fever is a symptom of a wide array of diseases, including infectious, non-infectious, neurogenic, drug-induced, and fever of unknown origin.
- Trends in body temperature over time are more telling than any single temperature reading.

Conclusion

Fever is defined as an elevated body temperature of at least 38°C (100.4°F) and is a complex physiological response involving the hypothalamus and various pyrogens. It serves as a part of the body's defense mechanism against infections and other inflammatory conditions. Understanding the mechanisms, causes, and clinical implications of fever is essential for effective diagnosis and treatment.

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What is considered a fever?

Summary

Introduction

Key Insights

Conclusion

Sources and full results

Current concepts of fever

Fever is a regulated re-setting of body temperature, with its evolutionary history suggesting beneficial effects, but its precise nature has only recently been established.

The neurologic basis of fever.

Fever is a complex, adaptive response to immune challenge, involving autonomic, neuroendocrine, and behavioral mechanisms.

Concepts of fever: recent advances and lingering dogma.

Modern concepts of fever have evolved from a simple rise in core temperature to a complex physiological response involving cytokine-mediated temperature rise, acute-phase reactants, and activation of various physiological, endocrinologic, and immunologic systems.

Fever

Fever is a symptom of various diseases, with various etiologies, and can lead to short and long-term dysfunction and death.

Combating infection: should you treat a fever?

A fever is a temporary state of elevated core temperature, and should be treated if it persists for more than 24 hours or if it is caused by a viral or bacterial infection.

Fever

Fever is a rise in core body temperature of greater than 37.8°C, with common causes being viral infections, bacterial infections, and parasitic infections.

The experimental approach to the mechanism of fever.

Fever is a manifestation of disease, and its pathogenesis is influenced by tissue injury, infection, and inflammation.

The evolution of the concept of 'fever' in the history of medicine: from pathological picture per se to clinical epiphenomenon (and vice versa).

The medical concept of fever has evolved from a systemic disease to a clinical sign of various diseases, with the clinical thermometer being widely used in medical practice only in the mid-19th century.

Inhibition of Fever

Fever is a common cause of death in livestock, with its severity varying by the type of infection, tissue damage, or neoplasms present.

Fever and sickness behavior: Friend or foe?

Fever and sickness behaviors are both brain-controlled symptoms and can be beneficial or harmful during various illnesses, influencing our approach to antipyretics during illness.

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