Prolonged Fever in Children

Father taking child's temperature
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Having a child with a prolonged or persistent fever can be frustrating, both for a parent and their pediatrician. On the one hand, you don't want to overreact and put a child through a lot of unnecessary tests for what could be "just a virus," but then you also don't want to miss anything treatable or even more importantly, miss something very serious. Doctors usually use a step-wise approach when managing a child with this symptom.

Prolonged Fever of Unknown Origin

A prolonged fever is simply one that lasts longer than usual, for example, more than the seven to 10 days that you would expect with a simple viral infection. Antibiotics usually aren't prescribed just because a child has a fever that is lasting a long time. In many cases, no specific cause of the fever is found, and it just stops.

Fever of unknown origin (FUO) has often been defined as having a fever for three weeks or more without a known reason after one week of doctors trying to figure out the cause of the fever.

Evaluating a Child With Prolonged Fever

If your doctor sees your child early in the illness, within the first three to five days, she may decide to just observe your child after a full physical exam and depending on how well or sick your child seems. After that, your pediatrician will likely do more testing if the fever persists, like the strep test and blood count, depending on your child's other symptoms.

At that point, if your child still has a fever, he almost certainly needs to be seen again. This is especially important since you think he is getting worse. If you're not comfortable seeing your pediatrician again, then consider getting a second opinion from another pediatrician or by going to the emergency room at a children's hospital.

Further testing might include:

  • Chest X-ray
  • Urinalysis and urine culture
  • Blood culture
  • Testing for mono
  • Repeat blood count
  • Liver function tests
  • PPD to test for tuberculosis
  • HIV test
  • Sedimentation rate (ESR) and C-reactive protein (CRP) test
  • Viral respiratory panel

A detailed physical exam might provide further clues, especially looking out for mouth ulcers, rashes, swollen lymph glands, or classic symptoms of pediatric diseases such as Kawasaki disease.

After several weeks of a child having a fever of unknown origin (FUO), testing for less common things is done. This might include an abdominal sonogram or CT scan to look for a hidden abscess, stool cultures, an ANA (arthritis test), thyroid function tests, and antibody testing for other infections.

If all of that is normal, then testing for non-infectious causes of fever, like juvenile rheumatoid arthritis, malignancies, and inflammatory bowel disease usually comes next.

Coughing might point to a respiratory illness as the cause of his fever, like a cold that turned into pneumonia or a sinus infection. Walking pneumonia or mycoplasma pneumonia can cause a high fever and may also be a possible cause of his symptoms. It is not unusual for this infection to last one to three weeks before a child starts to show improvement.

Clues to FUO Cause

In addition to your pediatrician, a pediatric infectious disease specialist and a pediatric rheumatologist might be helpful if your child has a prolonged fever. To help your doctors narrow down what is causing your child's fever, consider the following questions and possible sources of the fever:

  • Has he been around anyone else that has been sick?
  • Has he missed any of his routine vaccines? (Your doctor might not think of vaccine-preventable diseases, figuring he should be vaccinated and protected against them)
  • Has he traveled out of the country recently? (malaria or other diseases)
  • Has he been around any farm animals or wild animals? (brucellosis, tularemia)
  • Do you have any pets? (Salmonella infections from reptiles and psittacosis from birds)
  • Has he been bitten by a tick? (Lyme Disease, Q fever, Rocky Mountain spotted fever)
  • Has he been scratched by a kitten? (cat-scratch disease)
  • Has he eaten any raw or undercooked foods or drink unpasteurized milk or juice?
  • Does he have a heart murmur? (bacterial endocarditis)
  • Has he been taking any medications? (drug fever)
  • Does anything like this run in the family? (familial Mediterranean fever)
  • In addition to the fever, has he had other symptoms, like night sweats and weight loss? (lymphoma)
  • Has he had episodes like this before and were they associated with ulcers in his mouth? (PFAPA syndrome)
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    Article Sources

    1. Rigante D, Esposito S. A roadmap for fever of unknown origin in children. International Journal of Immunopathology and Pharmacology. 2013;26(2):3I5-326.  doi:10.1177/039463201302600205

    2. Marshall GS. Prolonged and recurrent fevers in children. J Infect. 2014;68 Suppl 1:S83-93.  doi:10.1016/j.jinf.2013.09.017

    3. Colvin JM, Muenzer JT, Jaffe DM, et al. Detection of viruses in young children with fever without an apparent source. Pediatrics. 2012;130(6):e1455-62.  doi:10.1542/peds.2012-1391

    4. Niehues T. The febrile child: diagnosis and treatment. Dtsch Arztebl Int. 2013;110(45):764-73.  doi:10.3238/arztebl.2013.0764

    5. Manual on Paediatric HIV Care and Treatment for District Hospitals: Addendum to the Pocket Book of Hospital Care of Children. World Health Organization. 2011.

    6. Rowley A, Ryan S. Kawasaki Disease. Clinician Reviews. 2013;23(2):34-38.

    7. Eken Y. Fever of unknown origin with polyarthritis. J Pediatr Care. 2016; 2:3. doi:10.21767/2471-805X.100017

    8. Cuffari C. Diagnostic Considerations in Pediatric Inflammatory Bowel Disease Management. Gastroenterol Hepatol (N Y). 2009; 5(11): 775–783.

    9. Pneumonia: Atypical (Walking) Pneumonia. Cleveland Clinic. 2015.

    10. Statler VA, Marshall GS. Characteristics of Patients Referred to a Pediatric Infectious Diseases Clinic With Unexplained Fever. J Pediatric Infect Dis Soc. 2016;5(3):249-56.  doi:10.1093/jpids/piv008

    11. Soon G. Approach to recurrent fever in childhood. Can Fam Physician. 2017;63(10): 756–762.

    Additional Reading

    • American Academy of Pediatrics. Red Book: 2015 Report of the Committee on Infectious Diseases. Elk Grove Village, IL: American Academy of Pediatrics; 2015.
    • Long SS, Pickering LK, Prober CG. Prolonged, Recurrent, and Periodic Fever Syndromes. Principles and Practice of Pediatric Infectious Diseases (Fourth Edition), Part II, 2012, Pages 117-127.