Pyrexia/Fever of Unknown Origin

In case of pyrexia of unknown origin, which is a common presenting symptom for all ages, in adults there usually would be some localising signs or symptoms, which point to a likely focus of infection.

If after careful examination no clear focus of infection is identified, the following should be considered in a previously healthy patient admitted from the community with fever of less than two weeks' duration:

Viral infections (frequently resolve after 4-5 days, or may be the prodromal phase, for example, hepatitis)
Malaria
Tyhoid
Urinary tract infection
Bacteraemia
HIV related causes of fever

If HIV is suspected see guidelines in the chapter on HIV related diseases.

If the patient's general condition is satisfactory, it is reasonable to withhold antibiotics while carrying out a few basic investigations: that is urinalysis (dip-stick), urine microscopy, haemoglobin, white cell count and differential and malarial parasites which are all within the capabilities of e.g. a district hospital laboratory. If possible send a blood culture to the nearest microbiology diagnostic laboratory (NMRL and the TB laboratories). Liver function tests and urine testing for bile products are appropriate if hepatitis is suspected. If no improvement occurs after 3-4 days and there is still no identifiable focus of infection, and there is no evidence of malaria (at least two negative blood films) the subsequent management of the patient should be guided by further results of the investigations.

In those patients who present very ill or toxic, or whose condition deteriorates, antibiotic therapy should be initiated on the basis of clinical suspicion. (typhoid - ciprofloxacin; staphylococcal septicaemia - cloxacillin, etc, anaerobes - metronidazole).

Recommended 'blind' therapy for septicaemia with no identifiable source is as follows:

	Medicine	Dose	Frequency	Duration
	ceftriaxone iv	2g	twice a day	7-14 days
and	gentamicin iv	4-5mg/kg	once a day	max 2 weeks

Alternative:

	Medicine	Dose	Frequency	Duration
	chloramphenicol iv	1g	4 times a day	review
and	gentamicin iv	4-5mg/kg	once a day	max 2 weeks