Fever Patterns - Differential Diagnosis Framework



Continuous Fever:

Temp > 38°C with only 1 degree fluctuation in 24 hours

	• Viral and bacterial infections

	• Typhoid fever (Step ladder: fever plateaus at 103-104°F)

	• Lobar pneumonia

	• Rickettsial diseases

	• Brucellosis

	• Typhus, gram-negative pneumonia

	• Acute bacterial meningitis



Remittent Fever:

Temp > 38°C with fluctuation more than 2°C in 24 hours

	• Viral infections

	• Acute bacterial endocarditis

	• Typhoid fever

	• Rickettsiae infections



Intermittent Fever:

High spike and rapid resolution falling to normal

	• Pyogenic/focal infection

	• Abscess, bacteremia

	• Malaria

	• Lymphoma

	• TB

	• Juvenile idiopathic arthritis

	• Infective endocarditis, malaria

	• Leptospira

	• Borrelia, schistosomiasis

	• Pyemia



Malarial Intermittent Fevers:

 • Intermittent tertian: P. vivax & ovale

 • Intermittent subtertian: P. falciparum

 • Quotidian (daily): P. knowlesi



Double Quotidian Fever:

2 distinct daily peaks of fever

	• Visceral leishmaniasis

	• Adult Still's

	• Gonococcal endocarditis



Other Recurrent Fevers:

	• Still's disease

	• Crohn disease

	• Behcet disease

	• Drug fever

	• Factitious fever



Periodical Fever:

Periods with low-grade fever or no fever

	• Malaria

	• Lymphoma

	• Borrelia

	• Rat-bite fever

Fever months/years without bacterial/viral source

Non-Infectious Causes:

	• Still's disease

	• Rheumatoid arthritis

	• Crohn's disease

	• Behcet's syndrome

	• Cyclic neutropenia



Typhus Inversus Pattern:

Reversal of the usual diurnal pattern (Temp high in AM > PM)

	• Disseminated tuberculosis

	• Typhoid fever

	• Polyarteritis nodosa

	• Endocarditis

	• Hepatic abscess



Hereditary Periodic Fever:

	• Familial Mediterranean fever

	• Hyper-IgD syndrome

	• Tumor necrosis factor receptor-associated periodic syndrome



Biphasic Fever:

	• Dengue fever

	• Leptospirosis



Pel-Ebstein Fever:

Fever 1-2 weeks followed by an afebrile period of 1-2 weeks

	• Hodgkin lymphoma



Relapsing Fever:

Fever followed by an afebrile period of several days

	• Tick-borne relapsing fever

	• Louse-borne relapsing fever



Undulant Fever:

Temperature rises gradually and falls (like a wave) over days to weeks

	• Brucellosis



Faget's Sign - Temperature Pulse Dissociation:

For every 1°F rise in temp, HR incrementally increases by 8-10 bpm (Liebermeister’s rule)

Fever Associated with Relative Bradycardia:

	• Legionnaire's disease

	• Chlamydia

	• Salmonella typhi (typhoid fever)

	• Dengue

	• Babesiosis

	• Leishmaniasis

	• Brucellosis

	• Psittacosis

	• Mycoplasma pneumonia

	• Yellow fever

	• Tuberculous meningitis

	• Blackwater fever (Falciparum malaria with profound hemolysis)

	• Malaria

	• Leptospirosis

	• Viral hemorrhagic fevers



Fever + Night Sweats:

	• TB

	• Nocardia

	• Brucellosis

	• Liver or lung abscess

	• Sub-acute infective endocarditis

Non-Infectious Diseases:

	• Polyarteritis nodosa

	• Lymphomas



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