Many Causes of a Fever or Causes Running a Higher Than Normal Temperature

Thermometers

A fever is when you body’s temperature is higher than normal, and its treatment depends on the cause of this fever.
A fever is not an illness.
Some of the possible causes for running a higher than normal temperature are:

Lupus
Cancer
Sepsis
Sinusitis
Cellulitis
Meningitis
Gonorrhea
Pneumonia
Appendicitis
Tuberculosis
Ear infections
Mononucleosis
Coxsackie virus
Acute bronchitis
Ulcerative colitis
Rheumatoid arthritis
Autoimmune disorders
AIDS and HIV infection
Colds or flu type illnesses
Viral or bacterial infections
Avian [...]

Fever Causes for a Higher than Its Normal Body Temperature

Thermometers

A fever is your body at a higher than “its normal” temperature. Increasing your body’s temperature is one weapon in defense against infection.
Most bacteria and viruses that cause infections thrive in the 98.6 F “normal” body temperature. Increasing this norm temp slightly (fever) creates a negative environment for their survival.
In addition, running a fever [...]

Dengue Fever High Fever, Frontal Headache and Joint/Muscle Pain Symptoms

Dengue is a disease found in most tropical and subtropical areas of the world, and is transmitted to humans by a bite of an infected mosquito. Its incubation period is 3-14 days.
Dengue fever is characterized by the sudden onset of high fever, severe frontal headache, and joint and muscle pain. Many experience:

nausea
vomiting
rash ~ [...]