febris

Febris is the Latin term for fever, a historical and clinical concept that remains central in modern medicine. In English usage, fever denotes a temporary elevation of core body temperature, typically above 38°C (100.4°F). Normal temperatures vary by person and method of measurement; fever is often a sign of the body's immune response to infection, inflammation, or other disease processes. More severe hyperthermia, exceeding about 41°C (105.8°F), is a medical emergency.

Mechanism and signs: fevers are usually produced when pyrogens—exogenous substances from pathogens or endogenous cytokines such as IL-1, IL-6 and TNF-alpha—act on the hypothalamus to raise the body's set point. The result is heat production through shivering and reduced heat loss, followed by sweating as the set point falls back toward normal. Common accompanying symptoms include malaise, chills, sweating, and dehydration.

Causes and classification: the most frequent cause is infection (viral, bacterial, fungal, parasitic). Non-infectious triggers include autoimmune or inflammatory diseases, malignancies, drugs, and environmental heat exposure. Fever patterns can be intermittent, remittent, quotidian, or sustained. Fever of unknown origin (FUO) is a historical and clinical concept describing fever above 38.3°C lasting several weeks with no diagnosis after systematic evaluation; definitions vary by setting.

Management and prognosis: evaluation aims to identify an underlying cause. Treatment emphasizes treating the root condition and symptom relief with antipyretics such as acetaminophen or NSAIDs, while considering age, pregnancy, and comorbidities. Aspirin is discouraged in children due to the risk of Reye syndrome. Fever is a common, often adaptive response but requires careful assessment in certain populations.