Russell Lewis
Associate Professor, Infectious Diseases
Department of Molecular Medicine
MEP 2491 Infectious Diseases
13 March 2023
The legend of Febris was said to center around the haunting marshes of Camagna in Southern Italy where like clockwork every year, the people would become deathly ill with a mysterious disease. She was so feared by the Romans that the suffering population had created a cult to Febris. They went so far as to wear protective amulets and build her temples in order to worship her to win her favour.
Wunderlich’s pioneering studies of thermometry-normal 37°C
Since the 19th century, humans have become gradually colder-0.05° to 0.5°C per decade
Current normal range is 36.3 to 36.5°C
Temperature of > 38.3°C > 3 weeks
Fever >2 separate outpatient visits with diagnostic investigations or
Fever >2 visits in hospital of 3 days with diagnostic investigations
Infections (geography dependent)
Inflammatory conditions (age dependent)
Cancer (age dependent)
Undiagnosed /unknown
Infectious causes decrease in patients above age 65 years
Travel
Contacts
Animal and insect exposure
Medications
Immunizations
Family history
Cardiac valve disorder
Temporal arteritis
Polymyalgia rheumatic syndromes
intraabdominal abscess
Complicated UTIs
Tuberculosis
Endocarditis
Drug fever
Post-operative complications (e.g., occult abscess)
Decubitus ulcers
Septic thrombophlebitis
Recurrent pulmonary emboli
Myocardial infarction
Cancer
Blood transfusion
Reactions to contrast media
Clostridium difficile colitis
Abscess
Drug fever
Postoperative complications
Septic thrombophlebitis
Recurrent pulmonary emboli
Myocardial infarction
ANC= Total WBC x (% Segs + % Bands)
Neutropenia is defined as an ANC of < 500 cells/mm3 or an ANC that is expected to decrease to < 500 cells/mm3 during the next 48 h.
Fever occurs frequently during chemotherapy-induced neutropenia:
10%–50% of patients with solid tumors
80% of those with hematologic malignancies will develop fever during >1 chemotherapy cycle associated with neutropenia
Most patients will have no infectious etiology documented.
Signs of inflammation are notoriously absent other than fever
Signs and symptoms | Infection | % of patients with ANC< 100 | % of patients with ANC>1000 |
---|---|---|---|
Fever | Overall | 98 | 76 |
Bacteremia | Overall | 43 | 13 |
Fluctuance | Anorectal | 8 | 67 |
Exudate | Skin | 5 | 92 |
Purulent sputum | Pneumonia | 8 | 84 |
Pyuria | UTI | 11 | 97 |
Temperature >37.8°C at least once a day;
Duration of fever >2 weeks;
Lack of evidence of infection (eg physical examination, laboratory examinations, and imaging studies);
Absence of allergic mechanisms (eg, drug allergy, transfusion reaction, and radiation or chemotherapeutic drug reaction);
Lack of response of fever to an empiric, adequate antibiotic therapy for at least 7 days;
Prompt complete lysis by the naproxen test with sustained normal temperature while receiving naproxen.
Comprehensive history |
---|
Repeated physical exams |
Complete blood count |
Routine blood chemistry |
Urinalysis including microscopic examination |
Chest radiograph |
Erythrocyte sedimentation rate, C-reactive protein |
Antinuclear antibodies |
Rheumatoid factor |
Blood cultures- three separate specimens in the absence of antimicrobial therapy |
CMV IgM antibodies or viral detection in blood |
Heterophil antibody test in children and young adults |
Tuberculin skin test |
Computed tomography of abdomen, pelvis and other sites |
MRI/Radionucleotide scans |
HIV antibodies or viral detection assay |
Further evaluation of any abnormality detected by above tests |
Various duplex imaging of lower limbs |
Recent travel
Exposure to pets and other animals
Work environment
Recent contact with people with similar symptoms
Family history (e.g., familial Mediterranean fever)
Lymphoma
Rheumatic fever
Intraabdominal disorders
Hydration, ambient temperature
Accuracy of temperature measurements
Use of antipyretics, corticosteroids
Blood transfusions, other medical interventions etc.
Febrile paroxysms may occur every other day for P. vivax, P. ovale, and P. falciparum and every third day for P. malariae. Paroxysms occurring at regular intervals are more common in the setting of infection due to P. vivax or P. ovale than P. falciparum. With improvements in early diagnosis and treatment, this traditional description of cyclic fever is seen infrequently.
Miliary TB
Salmonelloses
Hepatic abscess
Bacterial endocarditis
“The cause is more often a common disease presenting in an atypical fashion than a rare disease presenting in a typical fashion.
False positives
Misguided treatment plans
CT of abdomen, chest
Ultrasound of gallbladder and hepatobiliary systems
CT pulmonary angiograms for pulmonary embolus
MRI for CNS, abdomen spleen and lymph nodes Aortic arch and proximal cervical arteries (vasculitis)
The indium 111- tagged white blood cell (WBC) scan (becoming less comon)
Gallium-67 (67Ga) scan (replaced by PET-CT)
Histopathological examination of tissues obtained by excisional biopsy , needle biopsy or laparotomy can provide definitive diagnosis in some cases
Majority of FUO patients will undergo at least one procedure
A fundamental principle in classic FUO is that therapy should be withheld until the cause of fever is determined
Non-specific treatment rarely “cures” FUO
Empiric treatment may delay the clinical diagnosis
Clinical reality is that therapeutic trials with corticosteroids, aspirin, antimicrobial agents may be considered
May delay correct diagnosis/treatment
The road to diagnosis of FUO is, by definition, long and frustrating
Clinicians are often pressured to treat symptoms
Intra-abdominal infections
Miliary tuberculosis
Disseminated fungal infections
Recurrent pulmonary emboli