Touch is sensitive (90%) but not specific (50%) for fever - so don't dismiss parental reporting entirely. J Trop Pediatr. 2008 Feb;54(1):70-3 PMID 18039678 Tympanic thermometer does not reliably correlate (wax? angle?) and misses about 1 in 8 fevers Acad Emerg Med. 2000 Sep;7(9):1061-4. PMID 11044005 (although NICE offers as option).
The quoted 1% risk of invasive bacterial disease in young children with unexplained fever presenting to hospital is almost certainly a considerable overestimate. The NICE guideline differentiates Red symptoms/signs that clearly indicated serious illness, whereas the Amber group includes the vast majority of children. And anyway, we know signs and symptoms other than classic neck stiffness etc fails to predict outcome; best predictor was "something is wrong" - hence most important primary care action is prompt clinical assessment by experienced clinician. BrJGP 2007;57:538, pmid 17727746
Under 3 months - if previously healthy, no evidence of focus, normal WCC then risk is minimal. Empirical treatment for the under 1 month, see Baraff. (Peds 97;100) Ambulatory care suggested by Dagan back in 1988 (J ped 112). With universal conjugate Pneumococcal vaccine, the chances of invasive bacterial infection are much less than they used to be. Remember that if fever has been of short duration eg under 12 hrs, inflammatory markers become less reliable. Pratt, Peds International 2007 PMID 17250502
Baraff now recommends that all febrile neonates get full sepsis screen including LP. Between 1 and 3 months of age the rate of serious bacterial infection is much lower - if non-toxic looking (see below), use inflammatory markers only.
Over 3 months - fever greater than 39 predicts bacteraemia in 3% of kids before Prevenar (conj pneumococcal vaccine) - now more like 0.7%; but usually transient and not requiring antibiotics! Children vaccinated against Pneumococcus have 10% the risk of invasive pneumococcal disease. If non-toxic, and vaccinated, then urinalysis and urine culture. (Annals Emerg Med 2000;36)
NB even if a risk falls to 1%, the cumulative chance of getting at least 1 positive after 100 patients rises to 50%!
Lacour scoring system ("Laboratory-Score") based on CRP, PCT and urinalysis. Has sensitivity of 94%, spec of 81%. Would reduce incidence of antibiotic use from 65 to 40% but good enough? Lacour, PIDJ 2008 PMID 18536624
Convalescent serology for culture negative cases may reveal causative organism eg Flu, EBV, CMV, Parvo.
Hyperpyrexia (> 41.1.degC): 20% will have serious bacterial infection. Chronic underlying illness or diarrhoea increases the risk, rhinorrhoea or other viral symptom decreases it. Age, maximum temperature, and total white blood cell count were surprisingly not predictive of either bacterial or viral illness! (n=103). (Pediatrics. 118(1):34-40, 2006 PMID 16818546)
A systematic history and repeated, careful examination is the key to diagnosis. Measure and document the temperature during a period of close observation (beware factitious fever). If possible, stop all drugs. Antipyretics may add to the comfort of the child, and response to these drugs, particularly to NSAIDs may assist in the characterization of fever. But they may not do much for infection, may obscure the pattern of fever, and can occasionally be its cause. Investigate for common conditions presenting in an unusual way before thinking of rare causes of FUO, resist the temptation to work down lists of tests - be guided by the clues given in the history and examination. Unless the child is critically ill, do not treat empirically. If the diagnosis remains obscure, go back and take the history again, send the specimens again!
The most widely accepted definition of FUO is fever with documented temperatures of 38.3C on several occasions, persisting for more than 3 weeks, and uncertain diagnosis after intensive study during hospital admission for at least a week. However, this is used for adults, and with better, quicker diagnostic tests, and better imaging techniques, a FUO could reasonably be defined as the presence of fever for 8 days or more in a child in whom a careful thorough history and physical examination, and preliminary laboratory data fail to reveal a probable cause for the fever. There are reports of over 200 causes of FUO. Infection is the commonest cause in children in whom a diagnosis is eventually reached, amounting to around 40% of cases. 12-15% have collagen vascular disease. Malignancy is even less common (cf adults), chiefly leukaemia and lymphoma, 5-13% of cases.
| Infectious diseases - Bacterial |
| Brucellosis |
| Bacterial endocarditis |
| Liver abscess |
| Mastoiditis |
| Osteomyelitis |
| Pelvic abscess |
| Perinephric abscess |
| Pyelonephritis |
| Salmonellosis |
| Sinusitis |
| Subdiaphragmatic abscess |
| Tuberculosis |
| Infectious disease - Viral |
| CMV |
| Hepatitis |
| HIV |
| EBV |
| Infectious diseases - Other |
| Leptospirosis |
| Lyme disease |
| Q fever (dead animals) |
| malaria |
| syphilis |
| toxocariasis |
| Chlamydial |
| Tularaemia |
| Collagen vascular disease |
| Juvenile idiopathic arthritis |
| Systemic lupus erythematosus |
| Behcet's disease |
| Kawasaki disease |
| Sarcoid |
| Familial Mediterranean Fever - arthritis, serositis |
| Malignancy |
| Hodgkin disease |
| Leukaemia/lymphoma |
| Neuroblastoma |
| Diencephalic fever - usually with failure to thrive & vomiting. |
| Hepatoma |
| Atrial myxoma |
| Miscellaneous |
| Drug fever - usually after 2+ weeks broad spectrum antibiotics |
| Factitious fever - look for absence of tachycardia, rapid defervescence without sweating, absence of diurnal variation, normal rectal temperature |
| Familial dysautonomia |
| Ectodermal dysplasia |
| Crohn's disease |
| Periodic fever - see Immunology |
| Thyrotoxicosis |
| Cystic Fibrosis |
Maximum/minimum temperature, the method of measurement used, any association with location, or with time of day, and whether there are afebrile periods, and if so, how long they last. Some diseases have characteristic fever patterns, such as malaria (spikes every 2, 3 or 4 days depending on species) and juvenile idiopathic arthritis (big spikes with return to or below baseline). Weight loss, infectious contacts (TB), visitors from abroad (typhoid) and sexual contact. Blood transfusions, and exposure to needles (accidental or otherwise). Animal, bird and insect exposure. Pets (anybody's) - kittens spread bartonella (cat-scratch disease), farm visits, recreational pursuits and local surroundings. Animal or tick bites or scratches (Mediterranean Spotted Fever = Rickettsia coronae, tick bite on leg from scrub ?eschar). Foreign travel, local travel eg farmland. Unpasteurized milk (M bovis). Pica (worms, toxoplasmosis). Drugs (incl over-the-counter preparations, herbal/alternative remedies). The immunization record esp recent or omitted doses, BCG. Family history (immunodeficiency, familial Mediterranean Fever, or dysautonomia).
Child with Kawasaki's disease is utterly miserable, unable to play, whereas a child with systemic juvenile arthritis looks quite well except at the peak of fever. A child who looks completely well despite a documented high temperature may raise the suspicion of factitious fever.
In those with low or episodic fever, and normal ESR and haematocrit, less than 10% will have a definitive diagnosis.
The pace at which further investigations need to be performed will be dictated by the general condition of the patient. Resist the temptation to initiate empirical treatment unless fear that untreated disease is becoming life-threatening.
See Prescribing for antipyretics.
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