Fever with relative bradycardia is seen in?

Appeared in: BHU NO - 2015

Explanation

Typhoid fever classically presents with a dissociation between a high temperature and a relatively slow pulse rate.
This phenomenon is known as Faget's sign or relative bradycardia.
Normally, the heart rate increases by approximately 10 beats per minute for every 1°C increase in body temperature.
In typhoid, the pulse rate fails to rise in proportion to the fever, making it a key diagnostic clue.

Option A: Malaria is characterized by high-grade fever, often with severe chills and rigors. This physiological stress typically causes a significant increase in heart rate (tachycardia), not bradycardia.
Option C: Dengue fever usually presents with high fever and tachycardia. While bradycardia can sometimes occur, it is typically seen during the convalescent (recovery) phase or in severe dengue, not as the characteristic presentation during the febrile phase.
Option D: Diphtheria is a toxemic illness that typically causes a low-grade fever and tachycardia. The toxins can affect the heart (myocarditis), but this usually results in a rapid heart rate or other arrhythmias, not relative bradycardia.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Clinical signs of infectious diseases, specifically the relationship between fever and pulse rate (temperature-pulse dissociation) as background academic context rather than a clinical decision trigger.
A nurse's accurate assessment of vital signs, including temperature and pulse, is fundamental. Identifying a discrepancy like relative bradycardia can significantly shorten the time to diagnosis.
This finding should prompt the nurse to consider the patient's travel history and exposure to contaminated food or water, which are risk factors for typhoid.
What if? If the patient had a high fever and a pulse rate of 140 bpm, this would be relative tachycardia. In this case, conditions like sepsis, shock, or illnesses caused by toxins (like toxic shock syndrome) would be higher on the list of potential diagnoses, and typhoid would be less likely.

How to Approach the Question

First, identify the core clinical sign in the question: 'fever with relative bradycardia'.
Recognize this as a specific clinical pattern known as temperature-pulse dissociation or Faget's sign.
Recall or deduce the classic associations for this sign from your knowledge of infectious diseases.
Evaluate each option: Typhoid is the textbook example. Malaria, Dengue, and Diphtheria are typically associated with tachycardia during the febrile phase.
Select the option that is most famously and consistently linked with the described sign.

Concept Tested & Keywords

Concept Tested: Clinical signs of infectious diseases, specifically the relationship between fever and pulse rate (temperature-pulse dissociation).
Stem keywords: Fever, relative bradycardia
Lead-in keywords: seen in

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E6 Nelson Textbook of Pediatrics(2024) — Volume 1 p. 1643-1645

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