Fever of unknown origin Dr Rafat Mosalli

Different body sites Rectal standardRectal standard Oral  lowerOral  lower Axillary  lowerAxillary  lower Tympanic  lowerTympanic  lowerDocumented: In the absence of antipyreticsIn the absence of antipyretics In ED or office or by hx from reliable parents/adultsIn ED or office or by hx from reliable parents/adults

Fever Without Source “An acute febrile illness in which the etiology of the fever is not apparent after a careful history and physical examination.”“An acute febrile illness in which the etiology of the fever is not apparent after a careful history and physical examination.” Baraff et al, Pediatrics 1993; 92:1-12 Baraff et al, Pediatrics 1993; 92:1-12

Fever of Unknown Origin 1. Fever of 38  C or greater which has continued for a 2 to 3 weeks 2. Absence of localizing clinical signs 3. Negative simple investigations

Occult bacteremia “…a positive blood culture in the setting of well appearance and without focus (e.g. no pneumonia)“…a positive blood culture in the setting of well appearance and without focus (e.g. no pneumonia) Fleisher et al, J Pediatrics 1994 Fleisher et al, J Pediatrics 1994

Serious Bacterial Infection “…Include meningitis, sepsis, bone and joint infections, urinary tract infections, pneumonia and enteritis”“…Include meningitis, sepsis, bone and joint infections, urinary tract infections, pneumonia and enteritis” Baraff et al, Pediatrics 1993; 92:1-12 Baraff et al, Pediatrics 1993; 92:1-12

Frequency of febrile illness 35% of unscheduled ambulatory care visits35% of unscheduled ambulatory care visits 65% of kids see doc before age 2y65% of kids see doc before age 2y Majority (75%) for T < 39  CMajority (75%) for T < 39  C 13% T > 39.5 13% T > 39.5 

Epidemiology Incidence of bacteremia in febrile infants in post-Hib eraIncidence of bacteremia in febrile infants in post-Hib era 2-3% if 38  C2-3% if 38  C 39  C 39  C

Occult bacteremia organisms Streptococcus pneumonia > 85% Streptococcus pneumonia > 85% Neisseria meningitidis 3-5% Neisseria meningitidis 3-5% Others:Others: S. aureus S. aureus S. pyogenes (GAS) S. pyogenes (GAS) Salmonella species Salmonella species Haemophilus influenzae type B Haemophilus influenzae type B (now rare – previously 10%)

Outcomes of occult bacteremia without antibiotics Persistent fever56%Persistent fever56% Persistent bacteremia21%Persistent bacteremia21% Meningitis9%Meningitis9% S. pneumonia 6% S. pneumonia 6% H. Influenzae 26% (now rare) H. Influenzae 26% (now rare)

Should fever be treated? ProsPros Decrease discomfortDecrease discomfort Calm the familyCalm the family Extreme (>41  C) may cause permanent brain damage rare,rare,rareExtreme (>41  C) may cause permanent brain damage rare,rare,rare Decrease risk of febrile convulsions in prone kids??Decrease risk of febrile convulsions in prone kids??

Should fever be treated? ConsCons Adverse effect of antipyretic may outweigh benefitsAdverse effect of antipyretic may outweigh benefits May obscure diagnostic/prognostic signsMay obscure diagnostic/prognostic signs Fever usually short-lived and benignFever usually short-lived and benign Fever is normal and adaptive physiologic responseFever is normal and adaptive physiologic response

What is the eventual etiology of fever in children with FUO?

How should a child with FUO be evaluated? FUO is more likely to be an unusual presentation of a common disorder than a common presentation of a rare disorder.FUO is more likely to be an unusual presentation of a common disorder than a common presentation of a rare disorder. detailed history and thorough physical examinationdetailed history and thorough physical examination avoid indiscriminately ordering a large battery of tests.avoid indiscriminately ordering a large battery of tests.

Causes

Evaluation options [ ] CBC [ ] blood culture [ ] urinalysis [ ] urine culture [ ] CXR [ ] LP [ ] Nothing

Management options [ ] Admit [ ]Treat empirically, or [ ]Observe, no treatment [ ] Send home, follow-up within 24 hours [ ]Treat empirically, or [ ]No treatment

Treatment options [ ] Oral [ ]Amoxicillin [ ]Amoxicillin/clavulanate [ ]Other [ ] Intravenous [ ]Ceftriaxone [ ]Other

Fever Without Source Age 3 – 36 Months Risk of occult bacteremiaRisk of occult bacteremia 3-11%, mean 4.3% for T>39  C3-11%, mean 4.3% for T>39  C Risk greater withRisk greater with Higher temperaturesHigher temperatures WBC > 15,000 (13% vs 2.6%)WBC > 15,000 (13% vs 2.6%) Risk of pneumococcal meningitis (w/o abx tx) 0.21% (1:500)Risk of pneumococcal meningitis (w/o abx tx) 0.21% (1:500)

FWS – age 3-36 months: Consensus Recommendations CHILD APPEARS TOXIC:CHILD APPEARS TOXIC: ADMIT to hospitalADMIT to hospital Sepsis w/uSepsis w/u Parenteral abxParenteral abx

FWS – age 3-36 months: Consensus Recommendations CHILD NON-TOXIC, T < 39  CCHILD NON-TOXIC, T < 39  C No diagnostic tests or antibioticsNo diagnostic tests or antibiotics Acetaminophen 15 mg/kg prn for feverAcetaminophen 15 mg/kg prn for fever Return if fever persists > 48 hours or clinical condition deterioratesReturn if fever persists > 48 hours or clinical condition deteriorates

Heptavalent conjugate pneumococcal vaccine very efficaciousvery efficacious Likely to make most of the foregoing pneumococcal in 3-36 month group obsoleteLikely to make most of the foregoing pneumococcal in 3-36 month group obsolete Finally become routine by MCHFinally become routine by MCH Given at 2,4,6 month and 12-15m