Types of Intermittent Fever
Intermittent fever is characterized by temperature elevations that return to normal between episodes, and can be classified into several distinct patterns based on the periodicity and characteristics of the fever spikes.
Classical Fever Patterns
Quotidian Fever
- Pattern: Fever spikes occur daily (every 24 hours)
- Characteristics: Temperature rises once daily, typically in late afternoon or early evening, then returns to normal
- Historical association: Traditionally linked to phlegm in Galenic humoural pathology 1
- Common causes: Adult-onset Still's disease (AOSD) commonly presents with quotidian fever exceeding 39°C, lasting under 4 hours 2
Tertian Fever
- Pattern: Fever spikes occur every 48 hours (every third day)
- Characteristics: Fever on days 1 and 3, with day 2 being afebrile
- Historical association: Attributed to yellow bile 1
- Common causes: Plasmodium vivax or P. ovale malaria [@2,3@]
Quartan Fever
- Pattern: Fever spikes occur every 72 hours (every fourth day)
- Characteristics: Fever on days 1 and 4, with days 2-3 being afebrile
- Historical association: Linked to black bile 1
- Common causes: Plasmodium malariae malaria [@2,3@]
Double Quotidian Fever
- Pattern: Two fever spikes within 24 hours
- Characteristics: Temperature rises twice daily with return to baseline between episodes
- Common causes: AOSD, mixed malarial infections 2
Clinical Context-Based Classification
Infectious Causes of Intermittent Fever
Tropical/Travel-Related [@1,2,3@]:
- Malaria (22.2% of tropical febrile illnesses): Most important potentially fatal cause; P. falciparum typically presents within 1 month of return, while P. vivax/ovale can present up to 1 year later
- Enteric fever (2.3% of cases): Typhoid/paratyphoid with 7-18 day incubation; fever "almost invariable" with non-specific symptoms
- Dengue fever (5.2% of cases): PCR positive days 1-8 post-symptom onset
- Rickettsioses (1.7% of cases)
- Leptospirosis: Viremia during first 5 days
Non-Tropical Infectious Causes 3:
- Focal bacterial infections: Urinary tract, biliary tract, colonic infections
- Foreign body infections: Prosthetic material, catheters
- Infective endocarditis: Less frequent but important
- Tuberculosis: Can present with intermittent fever
- Yersinia enterocolitica
- Rare causes: Borreliosis, rat-bite fever, chronic meningococcemia, chronic EBV infection
Inflammatory/Autoinflammatory Causes [@13,18@]:
Most Common:
- Adult-onset Still's disease: Quotidian or double quotidian pattern, fever >39°C, salmon-pink evanescent rash, arthritis/arthralgias 2
- Juvenile chronic arthritis
Periodic Fever Syndromes [@15,18@]:
- PFAPA syndrome (Periodic Fever, Aphthous stomatitis, Pharyngitis, Adenitis): Most common periodic fever in childhood with stereotypical clockwork periodicity
- Cyclic neutropenia: Approximately 21-day cycles
- Genetic autoinflammatory diseases: Monogenic disorders with recurrent stereotypical episodes
Other Inflammatory Causes 4:
- Ankylosing spondylitis (occasional)
- Pulmonary embolism
- Sarcoidosis
- Crohn's disease
- Vasculitis
- Polychondritis
- Castleman disease
Diagnostic Approach Considerations
Key Clinical Distinctions
Fever Pattern Reliability: Modern evidence shows fever patterns have limited diagnostic specificity 5. Most patients have remittent or intermittent fever regardless of etiology. The exception is sustained fever, which nearly always occurs with Gram-negative pneumonia or CNS damage 5.
Critical Initial Steps:
Temperature measurement method matters 6: Use central methods (bladder catheter thermistors, esophageal balloon thermistors) when devices are in place, or oral/rectal temperatures over less reliable methods (axillary, tympanic, temporal artery)
Travel history is essential [@2,3,9@]: Exact dates, destinations, activities, and timing of symptom onset relative to return. Median time between return and presentation is 7 days 7
Malaria must be excluded first in all febrile travelers from tropics [@2,3,9@]: Up to three daily blood films required
Red Flags Requiring Urgent Evaluation
- Infants <3 months with fever >40°C: Elevated risk of severe bacterial infection (OR 6.3) 8
- Impaired consciousness, cutaneous hemorrhage, dehydration, capillary refill >3 seconds 8
- Jaundice with fever: Consider leptospirosis, viral hepatitis, viral hemorrhagic fever, yellow fever [@2,5,6@]
- Hepatosplenomegaly: Amoebic liver abscess, brucellosis, trypanosomiasis, visceral leishmaniasis [@2,5,6@]
Common Pitfalls
Do not rely on fever pattern alone for diagnosis 5. Hectic fever occurred in all disease categories, not just bacteremia. The clinical context, associated symptoms, and epidemiologic factors are far more valuable than the fever pattern itself.
Fever of Unknown Origin accounts for 17.8% of returning travelers with fever 7, emphasizing that not all cases will have immediate explanations despite thorough evaluation.