Fever
A fever was a medical symptom that describes an abnormally high increase in body temperature. It was most often a sign of systemic infection or sepsis and was often accompanied by delirium. Alternatively, the expression "running a temperature" means that someone has a fever. 

When Dr. Phlox visited Captain Jonathan Archer in his cell on Narendra III in 2152, Phlox pretended to diagnose Archer with xenopolycythemia in order to talk to him. Phlox asked Archer if he had any residual symptoms, such as a fever or dizziness, to which Archer replied that he only had a scratchy throat. ()

In 2154, Archer suffered from fever after T'Pau performed a Vulcan ritual on him. ()

In 2155, Elizabeth, a Human/Vulcan hybrid who was a binary clone from Trip Tucker and T'Pol's DNA, suffered from an elevated white blood cell count and a low-grade fever. ()

Leonard McCoy ran a high fever as a bad side effect of an accidental drug overdose of cordrazine, thus becoming horribly delusional and weak. He was nursed back to health by Edith Keeler. ()

In 2267, Spock suffered from fever, when he was undergoing plak tow, thus causing him some obvious physical discomfort and disorientation during his fight with James T. Kirk. ()

In 2268, having had Kirk incapacitated by Wu, Ronald Tracey told Hikaru Sulu that Kirk couldn't talk as he was feverish and delirious. ()

In 2269, Scotty named feverish as one of the emotional states he had seen Kirk in in the past. ()

After unknowingly returning from the  with polywater intoxication, Doctor Beverly Crusher noted of Geordi La Forge's medical readout that there was "still nothing wrong with him", but based on her visual assessment, "He looks like he's running a temperature but every instrument we have says he's not." ()

A high fever was a symptom of the "unknown virus" epidemic that infected 1/3 of the imhabitants of the  in 2364. ()

In 2366, Beverly Crusher treated Patahk's fever by keeping it down and trying to let the body heal itself. ()

In 2367, a simulation of Crusher told Will Riker that, among other symptoms, a strain of Altarian encephalitis had resulted in his experiencing fever. ()

Kamin had been feverish for three days when Jean-Luc Picard awakened in his place. ()

A high fever was a late symptom of the aphasia virus which Chief Miles O'Brien suffered from in 2369. ()

A fever was a symptom of the Larosian virus. ()

Victims of the Harvester biogenic weapon would show a fever. () 

Fever was an early sign of the macrovirus. ()

Vargas, a Starfleet officer stationed on AR-558, contracted a fever in 2375. ()

That same year, while looking after The Doctor, Captain Kathryn Janeway fell asleep. When she awoke suddenly, he stated that she looked ill and she admitted to having a headache. He examined her and, finding that she had a fever, tried to declare a medical emergency, but she told him she was busy helping a friend. ()

Types 
 Anaprolean Fever
 Anchilles fever
 Cartalian fever
 Correllium fever
 Rigelian fever
 Rigelian Kassaba fever
 Rugalan fever
 Zanthi fever

External link 
 

de:Fieber
Medical conditions