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The following text is from an archived Red Book® edition and may not reflect current recommendations or information. To view the current edition, click here.
Section 3. Summaries of Infectious Diseases
Diphtheria
Clinical Manifestations
Etiology
Epidemiology
Diagnostic Tests
Treatment
Isolation of the Hospitalized Patient
Control Measures
CLINICAL MANIFESTATIONS: Diphtheria usually occurs as membranous nasopharyngitis or obstructive laryngotracheitis. Local infections are associated with a low-grade fever and the gradual onset of manifestations over 1 to 2 days. Less commonly, the disease presents as cutaneous, vaginal, conjunctival, or otic infection. Cutaneous diphtheria is more common in tropical areas and among the homeless. Serious complications of diphtheria include upper airway obstruction caused by extensive membrane formation, toxic myocarditis, and peripheral neuropathies.
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ETIOLOGY: Corynebacterium diphtheriae is an irregularly staining, gram-positive, nonspore-forming, nonmotile, pleomorphic bacillus with 4 colony types (mitis, intermedius, bellanti, and gravis). Strains of C diphtheriae may be toxigenic or nontoxigenic. Extracellular toxin consists of an enzymatically active A domain and a binding B domain, which promotes the entry of A into the cell. The toxin gene is carried by a family of related corynebacteria phages. The toxin inactivates elongation factor-2, thereby inhibiting protein synthesis, in myocardial and peripheral nerve cells.
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EPIDEMIOLOGY: Humans are the only known reservoir of C diphtheriae, which is present in discharges from the nose, throat, and eye and skin lesions for 2 to 6 weeks after infection. Patients treated with an appropriate antimicrobial agent usually are communicable for fewer than 4 days. Transmission results primarily from intimate contact with a patient or carrier; rarely, fomites and foodborne sources serve as vehicles of transmission. Although infection can occur in people who are immunized, partially immunized, or not immunized, disease is most common and most severe in people who are not immunized or inadequately immunized. The incidence of respiratory diphtheria is greatest during autumn and winter, but summer epidemics may occur in warm, moist climates in which skin
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