Merck Manual

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Some Causes of Fever Based on Risk Factors

Some Causes of Fever Based on Risk Factors

Risk Factor

Cause

None (healthy)

Upper or lower respiratory tract infection

Gastrointestinal infection

Infection related to a catheter inserted in a vein (IV catheter infection)

Urinary tract infection, particularly in people with a urinary catheter

Infection or a pocket of blood (hematoma) at the site of surgery

Drugs

Transfusion reaction

Travel to areas where an infection is common (endemic areas)

Disorders that cause diarrhea

Zika virus Epidemic encephalitis Encephalitis is inflammation of the brain that occurs when a virus directly infects the brain or when a virus, vaccine, or something else triggers inflammation. The spinal cord may also be involved... read more , chikungunya Arboviruses Arbovirus, arenavirus, and filovirus are viruses that are spread from animals to people and, with some viruses, from people to people. The animal involved depends on the type of virus. Many... read more , Ebola virus Ebola Virus and Marburg Virus Infections Marburg and Ebola virus infections cause bleeding and organ malfunction. These infections often result in death. Marburg and Ebola infections are spread through handling live or dead infected... read more , Japanese encephalitis Encephalitis is inflammation of the brain that occurs when a virus directly infects the brain or when a virus, vaccine, or something else triggers inflammation. The spinal cord may also be involved... read more , rabies Rabies Rabies is a viral infection of the brain that is transmitted by animals and that causes inflammation of the brain and spinal cord. Once the virus reaches the spinal cord and brain, rabies is... read more , measles Measles Measles is a highly contagious viral infection that causes various cold-like symptoms and a characteristic rash. Measles is caused by a virus. Symptoms include fever, runny nose, hacking cough... read more Measles , and yellow fever Yellow Fever Yellow fever is a mosquito-borne viral disease that occurs mainly in the tropics. Yellow fever occurs only in the tropical areas of Central Africa, southern Panama, and South America. Some people... read more

Exposure to insects or animals that carry disease-causing organisms, called vectors (in the United States)

Birds: Psittacosis

A weakened immune system (immunocompromise)

Fungi: Infection due to Candida Candidiasis Candidiasis is a fungal infection caused by several species of the yeast Candida, especially Candida albicans. The most common type of candidiasis is a superficial infection of the mouth, vagina... read more Candidiasis , Aspergillus Aspergillosis Aspergillosis is an infection, usually of the lungs, caused by the fungus Aspergillus. A ball of fungus fibers, blood clots, and white blood cells may form in the lungs or sinuses. People may... read more Aspergillosis , Histoplasma Histoplasmosis Histoplasmosis is an infection caused by the fungus Histoplasma capsulatum. It occurs mainly in the lungs but can sometimes spread throughout the body. Histoplasmosis is acquired by inhaling... read more Histoplasmosis , Coccidioides Coccidioidomycosis Coccidioidomycosis is an infection, usually of the lungs, caused by the fungus Coccidioides immitis or Coccidioides posadasii. The infection is caused by inhaling spores of the fungus. If mild... read more Coccidioidomycosis , microsporidia Microsporidiosis Microsporidiosis is infection caused by Microsporidia, which are parasitic fungi. Symptoms depend on the organs infected, but infections can cause diarrhea, other intestinal symptoms, or eye... read more , Pneumocystis jirovecii Pneumonia is infection of the lungs. Pneumonia in people whose immune system is weakened or impaired (for example, by acquired immunodeficiency syndrome [AIDS], cancer, organ transplantation... read more , or fungi that cause mucormycosis Mucormycosis Mucormycosis is a fungal infection that can be caused by many different molds. Mucormycosis is acquired when spores produced by the mold are inhaled or, much less commonly, when they enter the... read more Mucormycosis

Drugs that can increase heat production

Anesthetics

Drugs that can trigger fever

Sulfa drugs

Phenytoin

Carbamazepine

Procainamide

Quinidine

Amphotericin B

Interferons (drugs that are based on substances produced by the immune system and that help block the reproduction of viruses)