Season of year Age General health Weight change Fever—presence, duration, and pattern Previous similar symptoms Previous infections and other illnesses Previous surgeries, dental procedures Preceding trauma Presence of outbreaks or epidemics in the community Exposures to infected individuals Exposures to farm or feral animals and pets Exposures to ticks and mosquitoes Sexual history, including possibility of sexual abuse Illicit drug use Transfusion of blood or blood products Travel history Daycare or school attendance Sources of water and food (e.g., undercooked meat, unpasteurized dairy products) Home sanitary facilities and hygiene Pica Exposure to soil-borne and waterborne organisms (e.g., swimming in brackish water) Presence of foreign bodies (e.g., indwelling catheters, shunt, grafts) Immunization history Immunodeficiency (chemotherapy, acquired, congenital) Current medications molecular microbiologic methods such as polymerase chainreaction, and assessment of the immune response with antibodytiters or skin testing. The acute phase response is a nonspecificmetabolic and inflammatory response to infection, trauma, autoimmune disease, and some malignancies. Acute phase reactantssuch as erythrocyte sedimentation rate and C-reactive proteinare commonly elevated during an infection but are not specificfor infection and do not identify any specific infection. Thesetests are often used to monitor response to therapy.
A complete blood count is frequently obtained for evidence of infection. The initial response to infection, especially in children, is usually a leukocytosis (increased number of circulating leukocytes) with an initial neutrophilic response to both bacterial and viral infections. With most viral infections, this response is transient and is followed quickly by a characteristic mononuclear response. In general, bacterial infections are associated with greater neutrophil counts than viral infections (Table 93-3). A shift-to-the-left is an increase in the numbers of circulating immature cells of the neutrophil series, including band forms, metamyelocytes, and myelocytes and indicates the rapid release of cells from the bone marrow. It is characteristic of the early stages of infection and, if sustained, bacterial infections. Transient lymphopenia at the beginning of illness and lasting 24 to 48 hours has been described with many viral infections. Atypical lymphocytes are mature T lymphocytes with larger, eccentrically placed, and indented nuclei classically seen with infectious mononucleosis caused by Epstein-Barr virus. Other infections associated with atypical lymphocytosis include cytomegalovirus infection, toxoplasmosis, viral hepatitis, rubella, roseola, mumps, and some drug reactions. Eosinophilia is characteristic of allergic diseases but may be seen with tissue-invasive multicellular parasites, such as the migration of the larval stages of parasites through skin, connective tissue, and viscera. High-grade eosinophilia (>30% eosinophils, or a total eosinophil count >3000/μL) frequently occurs during the muscle invasion phase
Table 93-2 Localizing Manifestations of Infection SITE LOCALIZING SYMPTOMS LOCALIZING SIGNS* Eye Eye pain, double vision, photophobia, conjunctival discharge Periorbital erythema, periorbital edema, drainage, chemosis, limitation of extraocular movements
Ear pain, drainage Red bulging tympanic membrane, drainage from ear canal
Upper respiratory Rhinorrhea, sore throat, cough, drooling, stridor, Nasal congestion, pharyngeal erythema, enlarged tonsils with exudate, tract trismus, sinus pain, tooth pain, hoarse voice swollen red epiglottis, regional lymphadenopathy