CHAPTER 16 Fever
Diagnostic reasoning: focused history
Measurement of temperature
Many people use touch to determine whether a fever is present. Although not a precise indication, touch can signal a high fever. During the early stages of fever, perfusion to the skin is decreased and skin temperature falls. In later stages, when temperature within the muscles has risen significantly, increased body temperature is reflected by increased skin temperature. In children, hands and feet should not be used to gauge a fever because they may be vasoconstricted and feel cold. Accurate temperature should be measured using a thermometer. Because of the diurnal variation in normal body temperature and the effect of physiological factors and body rhythms, frequent recordings throughout the day are needed to monitor fever.
Height of fever
Is the fever caused by a localized infection?
Key questions
Do you have frequency, burning, or urgency with urination?
Are you having unusual vaginal/penile discharge?
Do you have face or sinus pain?
Do you have nasal discharge? If so, what color is the discharge?
Do you have a cough? Is it productive? What color is the sputum?
Do you have any sores (aphthous ulcers) in your mouth?
Are you having any nausea/vomiting or diarrhea?
Genitourinary tract
Upper urinary tract infection (UTI) in adults commonly produces systemic symptoms with flank pain and fever (see Chapters 17, 31, and 32). Fever with cystitis is uncommon in adults, but children with UTIs present with systemic rather than localized signs and symptoms. UTI is the most common infection in girls younger than 2 years who present with a high fever and in all infants younger than 90 days with fever. Pelvic inflammatory disease in women may cause fever as well as an increased amount of vaginal discharge and bleeding after intercourse. Men who have an acute UTI often present with chills, high fever, urinary frequency and urgency, perineal pain, and low back pain. They may also have penile discharge.
Ear, nose, and throat symptoms
Viral infections of the upper respiratory tract are common and usually produce fever (see Chapters 14, 22, and 29). Otitis media is common in children. Fever may accompany both viral and bacterial pharyngitis. Pharyngitis is frequently manifested only by fever, with the infection localizing 1 or 2 days later. Acute sinusitis can produce a fever. Aphthous ulcers with pharyngitis and cervical lymphadenopathy are seen in children with periodic fevers.
Respiratory or gastrointestinal symptoms
Most febrile illnesses are caused by viral upper respiratory infection (URI), lower respiratory infection (LRI) (see Chapters 10 and 13), or gastrointestinal (GI) tract infection (see Chapter 2). Localized symptoms can help pinpoint the cause of the fever. Vomiting occasionally signals pneumonia.
Joint pain
Joint pain may indicate connective tissue disorders in adults and in children more than 6 years of age (see Chapter 20). Osteomyelitis or septic arthritis may also produce fever.
Skin rash
The prodromal period of a rash is an important historical clue to diagnosis (see Chapter 25). Fever and rash usually appear together 1-5 days after infection. Common eruption periods are as follows:
Chronic disease
Chronic conditions and systemic disorders (such as diabetes mellitus, human immunodeficiency virus [HIV], malignancies, neutropenia, and sickle cell anemia) compromise host resistance and increase susceptibility to infection. Prosthetic devices, such as heart valves or joint prostheses, also increase susceptibility to infection.
Tuberculosis or hepatitis exposure
Travel
Patients can be exposed to an emerging infectious disease based on their travel activities. A history of travel out of the country presents the possibility of infection with amebiasis, malaria, schistosomiasis, typhoid fever, or hepatitis A and B. Dengue is the most common vector-borne disease worldwide and is a differential diagnosis for acute febrile illnesses in patients who live or have recently traveled to the tropics or subtropical areas of the United States. Epidemiological surveillance data continually provide updates on patterns of occurrence of infections such as severe acute respiratory syndrome (SARS), avian influenza or “bird flu,” and West Nile virus (see Box 16-1).