May 2000
BAL HARBOUR, Fla. - Although physicians are seeing fewer patients with meningitis, thanks to the Haemophilus influenzae type b (Hib) vaccine, they still grapple with the evaluation of a child with fever of unknown source.
The goal in evaluating these children, said Gary Fleisher, MD, chief, division of emergency medicine at The Children's Hospital in Boston, is to decide which of these children has a serious, life-threatening infection.
"Although we are seeing less meningitis than we used to before Hib vaccine, there are few, if any, absolutes. Each patient is different. There are some clinical guidelines but you must also look at each patient closely. No approach is perfect. No matter how you go about managing the febrile child, you will over treat some children and you will miss some that will turn out to have more serious infections," said Fleisher, who is also professor of pediatrics at Harvard Medical School.
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There are six important considerations: the toxicity of the patient, the patient's immune status, length of fever, age, whether a source of infection can be identified and severity of the source.
"First, consider the appearance and immune status of the child. These are the trump cards to the approach of the febrile child," he explained. "If this particular patient is toxic or appears acutely ill, you are going to pull out all the stops, do an aggressive work-up, admit the patient to the hospital and start intravenous (IV) antibiotics."
If the child is immunocompromised, there will be a protocol that guides admission, testing and presumptive therapy. These two groups characterize the minority of children, however, so good diagnostic acumen is needed to determine the extent of the problem in the remaining children.
If the child has been febrile for a long period, broaden the differential diagnosis away from infection.
"Do a careful examination and try to find a source of the fever and make a specific diagnosis," he said. "If the child is immunocompetent and nontoxic with a brief fever, consider the age, whether there is an identifiable source of infection and the seriousness of the source. Age is important in determining your approach.
"The reason age is so important is that young children tend to have a higher incidence of serious bacterial infection, which declines with advancing age. Young patients are harder to diagnose with a serious infection. You cannot pinpoint it as well; the symptomatology tends to be non-specific."
In addition, infants tend to deteriorate more quickly and have a more generalized involvement. "You want a lower threshold for an aggressive work-up in a young patient," said Fleisher, who breaks the age of consideration into three groups: 0-90 days, 3-24 months and older than 24 months.
If the child is nontoxic or immunocompromised, and the fever is brief, consider the source. Despite the symptoms, "a viral infection in this age range is a questionable source ... you may have the suggestion of a viral infection, but you may still treat this as no source," he said.
The incidence of serious infection is high in young infants, so Fleisher suggests being thorough to avoid missing a potentially serious infection. "Generally, we'll do a sepsis work-up in these infants, no matter what the degree of fever, if we do not find a specific source," Fleisher said.
If that septic work-up is positive, they will treat that child. If that work-up is negative, they will subdivide the age. If that child is younger than 28 days, he or she will be admitted and given antibiotics and maybe acyclovir in case herpes is present.
"My approach in the patient who is slightly older is to discharge after a dose of intramuscular ceftriaxone (Rocephin, Roche) to cover all the bases, in case I am missing a case of urinary tract infection (UTI) or bacteremia with a normal urinalysis and white blood cell count."
The incidence of serious bacterial infections declines in children 3 to 24 months of age, but bacteremia is still a problem.
"Once again, you need to be a good clinician, perform a thorough physical examination, and see if you can identify a source. If you see pneumonia, you'll treat that, an otitis, you'll treat that, varicella or herpes stomatitis, you will manage these conditions appropriately," he said.
If the child has a fever with no specific infection, Fleisher relies on the height of the fever. "In the infant younger than 90 days, any fever was sufficient to do a septic work-up. But in this child, I don't think one needs to do a lumbar puncture unless there is specific evidence of meningitis. Data have demonstrated that bacteremia is usually associated with a high fever. You will occasionally see a child with a low-grade fever and bacteremia, but that is unusual. If a child 3-24 months has no source of infection, doesn't appear toxic or immunocompromised and has a brief duration of low-grade fever, then you worry less about meningitis and bacteremia," he said.
UTI is still a concern. Fleisher recommended a urinalysis on all boys younger than 6 months and all girls younger than 2 years.
If the child has a high fever, do a blood culture and complete blood count. Use that blood count to stratify children who are at risk of occult bacteremia.
In children older than 2, there is a lower incidence of serious bacterial infection and a physician can rely on the physical exam.
"If you find a focus of bacterial infection, you are going to treat that. If it is viral, you are going to locate that and provide symptomatic therapy," he said. Presumptive antibiotics are contraindicated unless there are special circumstances.
For more information:
- Fleisher Gary R. Approach to the febrile child. Presented at the 35th Annual Postgraduate Course - Perspectives in Pediatrics. Feb. 4-10, 2000. Bal Harbour, Fla.
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