Consider non-infectious causes of fever like rheumatologic diseases and malignancies.
Ask four key questions: Who is the host? What are the notable exposures? What is the syndrome? What doesn't fit?
Deep dives
Consider the broad differential diagnosis of fever
When encountering a patient with a fever, it is crucial to consider not only infectious causes but also non-infectious causes such as rheumatologic diseases and malignancies. Although infectious diseases are the main focus, physicians should also consider factors such as recent travel, new medications, and exposure to insects or pets that may contribute to the fever.
A framework for evaluating a fever of unknown cause
To effectively evaluate a fever of unknown cause, doctors can ask four overarching questions: 1) Who is the host? This includes considering factors like age, baseline immune status, and anatomical risk factors. 2) What are the notable exposures? This involves asking about time of year, insect or tick bites, travel history, sick contacts, sexual activity, and substance use history. 3) What is the syndrome? Assessing the chronicity of illness and identifying associated symptoms helps guide the diagnostic workup. 4) What doesn't fit? Keeping in mind that multiple infections can coexist and being attentive to any data that contradicts the initial diagnosis.
Diagnostic workup and evolving clinical reasoning
In conducting a focused diagnostic workup for a patient with fever, doctors should consider specific tests based on the suspected etiology. For tick-borne diseases, tests may include lime antibody and Western blot, anaplasma PCR, and blood smear or Babesia PCR. Additionally, evaluation for sexually transmitted infections, including HIV antibody testing, gonorrhea, chlamydia, and syphilis screening, is important. It is crucial to remember that clinical reasoning is an iterative process, and additional data obtained over time may shift the initial diagnostic approach.
Dr. Solomon, an Infectious Diseases specialist at Brigham and Women's Hospital, discusses his approach to fever with host, Walker Redd. In discussing Dr. Solomon's framework for clinical reasoning in infectious diseases and applying it to a case of fever of unclear etiology, they ask: Who is the host? What are the notable exposures? What is the syndrome? What doesn't fit?
