Some Causes of Acute Fever

Predisposing Factor

Cause

None (healthy)

Upper or lower respiratory tract infection

Gastrointestinal infection

Urinary tract infection

Skin infection

Hospitalization

IV catheter–associated bloodstream infection

Urinary tract infection (particularly in patients with an indwelling catheter)

Pneumonia (particularly in patients using a ventilator)

Atelectasis

Surgical site infection (postoperatively)

Deep venous thrombosis or pulmonary embolism

Diarrhea (Clostridioides difficile–induced)

Medications

Hematoma

Transfusion reaction

Pressure injuries (decubitus ulcers)

Travel to endemic areas

Coccidioidomycosis

Dengue fever (less common)

Diarrheal disorders

Hantavirus

Histoplasmosis

Legionnaires' disease

Malaria

Rickettsial infections (eg, African tick typhus, Mediterranean spotted fever)

Multidrug-resistant bacteria

Plague

Tularemia

Typhoid fever

Viral hepatitis

Zika virus infection, chikungunya, Ebola, Japanese encephalitis, rabies, measles, and yellow fever

Vector exposure (in United States)

Ticks: Rickettsiosis, ehrlichiosis, anaplasmosis, Lyme disease, babesiosis, tularemia

Mosquitoes: Arboviral encephalitis

Wild animals: Tularemia, rabies, hantavirus infection, monkeypox

Fleas: Plague

Domestic animals: Brucellosis, cat-scratch disease, Q fever, toxoplasmosis

Birds: Psittacosis, avian influenza

Reptiles: Salmonella infection

Bats: Rabies, histoplasmosis

Immunocompromise

Viruses: Varicella-zoster virus or cytomegalovirus infection

Bacteria: Infection due to encapsulated organisms (eg, pneumococci, meningococci), Staphylococcus aureus, gram-negative bacteria (eg, Pseudomonas aeruginosa), Nocardia species, or mycobacteria species

Fungi: Infection due to Candida, Aspergillus, Histoplasma, or Coccidioides species; microsporidia, Pneumocystis jirovecii; or fungi that cause mucormycosis

Parasites: Infection due to Toxoplasma gondii, Strongyloides stercoralis, Cryptosporidium species, or Cystoisospora (previously Isospora belli)

Medications and illicit drugs that can alter thermoregulation

Amphetamines

Methylenedioxymethamphetamine (MDMA, or Ecstasy)

Antipsychotics (can cause neuroleptic malignant syndrome)

Anesthetics (inhaled anesthetics such as halothane can cause malignant hyperthermia)

Methamphetamine

Thyroxine

Interferons

Medications that can trigger fever by a hypersensitivity reaction

Beta-lactam antibiotics

Sulfa drugs

Phenytoin

Carbamazepine

Procainamide

Quinidine

Amphotericin B

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