Unexplained Fever. It's Hot

Singer Peggy Lee [1] gained notoriety with her version of this John Davenport song in 1959, and it was rerecorded by Elvis, Madonna, and, most recently, Beyonce. Fever is hot. Popular culture’s description of fever over the decades parallels the terminology used in medical literature. In 1955, Keefer and Leard [2]first coined the term “prolonged and perplexing fevers”. Petersdorf and Beeson [3] added “Fever of Unknown Origin” (FUO) to the medical lexicon in 1961. In a survey in 1980, Schmitt [4] found that 52% of parents feared that fever of 40°C or even less can result in neurologic damage. He introduced the term “fever phobia.” Misconceptions about fever continue to persist almost 4 decades later in both patient and caregiver populations. Unexplained fever continues to be the “bread and butter” of primary care providers with the frequent support and guidance of pediatric infectious disease subspecialists. Infectious disease education has long categorized the causes of fever as follows: infectious, inflammatory, neoplastic, and other [5]. Definitions of FUO have changed, and the evaluation of FUO has moved to the outpatient arena, whereas it previously required hospitalization. Over the past 40 years, infectious diseases have become less common in published cases series of FUO with “no diagnosis” becoming more common. In this month’s Journal of Pediatric Infectious Diseases, Statler and Marshall [6] report their findings from a retrospective review of the charts of 221 patients referred to a pediatric infectious diseases clinic for the evaluation of unexplained fever over a 5-year period from 2008 to 2012. Approximately one third of the patients had prolonged, unexplained fever as the reason for referral with the remainder referred because of recurrent unexplained fever. Two thirds of the patients (33 of 48 patients) with FUO in this study never received a definitive diagnosis. This might be the result of the availability of more diagnostic modalities to the primary care provider such that the diagnosis was apparent before the referral to a pediatric infectious diseases subspecialist. However, the unmeasured influence of pediatric infectious disease telephone consultation guidance to provide a structured algorithm for evaluation of the pediatric patient with fever is a significant factor in earlier diagnosis prior to referral. Patients with prolonged fever underwent an average of 10 diagnostic studies before referral ranging from simple blood tests to more invasive studies such as lymph node biopsies. Median duration of fever was 30 days, which is longer than previous studies. This extended time period suggests that primary care providers are waiting longer before referring patients. Statler and Marshall’s [6] study describes patients with unexplained fever at the point in time when they are referred to a pediatric infectious disease subspecialist. The authors found that at this point in time serious diagnoses were unusual. The generalizability of the study pertains to the population that has been evaluated by a primary care provider, which often included telephone consultation with a pediatric infectious diseases subspecialist, and evidences that at this point very few cases of prolonged fever are serious and most are without a specific diagnosis. What is different now compared with 1970 or 1990? Although the timing of evaluation for unexplained fever and the etiologies of unexplained fevers have changed, the value of the pediatric infectious diseases subspecialist in supporting the primary care provider at the onset of a child’s illness and throughout the course of illness remains significant and even critical. A pediatric infectious diseases consultant who performs a careful history Editorial Commentary