Fever of Unknown Origin (FUO)
Normal body temperature is between 36.5 to 37.5 degrees centigrade. Any body temperature above 38 degrees centigrade is considered as fever. We should remember that rectal temperature is 0.7 degrees centigrade higher than the oral temperature. Temperature regulation is not exact until the child reaches the age of 14 years for girls and 18 years for boys.
There are very many etiologies of fever. Commonly, this could be due to dehydration, drug hypersensitivity, acute infections and collagen diseases.
When you say Fever of Unknown Origin (FUO), this term refers to fever which lasts for days, weeks or months, is resistant to ordinary methods of therapy and whose etiology is not immediately clear.
By doing an excellent history taking and thorough physical examination, a physician can diagnose cases of fever of unknown origin. Some of the historical data worth mentioning include the following:
1. History of contact with a tuberculous individual, exposure to contaminated food and water, infected urine and stool and animal or insect bites
2. History of travel to endemic areas ( malaria, amoebiasis)
3. History of pica ( parasitic and protozoal infections)
4. Immunization history
5. History of drug intakes
6. History of earaches, headache, cough, vomiting, pain and chills
The following are the causes of FUO in children:
1. Bacterial
2. Viral
3. Chlamydial
4. Rickettsial
5. Fungal
6. Parasitic
7. Unclassified ( sarcoidosis)
8. Collagen vascular diseases
9. Malignancies
10. Drug fever, factitious fever, pancreatitis, thyrotoxicosis
Laboratory evaluations are helpful in the diagnosis of FUO.
1. Blood and urine cultures are taken for aerobic and anaerobic organisms.
2. Tuberculin skin test and chest xrays
3. Urine cultures and radiographic investigation of the urinary tract is mandatory in
infants with recurrent FUO
4. Radiographic examibation of the sinuses and mastoids
5. Tests for salmonella
6. Bone marrow examinations
7. Radiographic examination of the skull, mandibles, clavicles, scapulae and ribs
8. Scanning to detect intraabdominal masses
Some patients may need hospitalization for continuous and close observation and supportive therapy. Most of the pediatric patients may improve and resume their normal growth and development.