Diphtheria is an acute, highly contagious toxin-mediated infection caused by Cory-nebacterium diphtheriae, a gram-positive rod that usually infects the respiratory tract, primarily the tonsils, nasopharynx, and larynx. The GI and urinary tracts, conjunctivae, and ears are rarely involved.
Transmission usually occurs through intimate contact or by airborne respiratory droplets from asymptomatic carriers or convalescing patients. Many more people carry this disease than contract active infection. Diphtheria is more prevalent during the colder months because of closer person-to-person indoor contact, however it may be contracted at any time during the year.
Thanks to effective immunization, diphtheria is rare in many parts of the world, including the United States. Since 1972, the incidence of cutaneous diphtheria has been increasing, especially in the Pacific Northwest and the Southwest, in areas where crowding and poor hygienic conditions prevail. Most victims are children younger than age 15; about 10% of patients die.
Most infections go unrecognized, especially in partially immunized individuals. After an incubation period of less than a week, clinical cases of diphtheria characteristically show a thick, patchy, grayish green membrane over the mucous membranes of the pharynx, larynx, tonsils, soft palate, and nose; fever; sore throat; and a rasping cough, hoarseness, and other symptoms similar to croup. Attempts to remove the membrane usually cause bleeding, which is highly characteristic of diphtheria. If this membrane causes airway obstruction (particularly likely in laryngeal diphtheria), symptoms include tachypnea, stridor, possibly cyanosis, suprasternal retractions, and suffocation, if untreated. Adenopathy and cervical swelling can occur. In cutaneous diphtheria, skin lesions resemble impetigo.
Complications include thrombocytopenia, myocarditis, neurologic involvement (primarily affecting motor fibers but possibly also sensory neurons), renal involvement, and pulmonary involvement (bronchopneumonia) due to C. diphtheriae or other superinfecting organisms.
CONFIRMING DIAGNOSIS Examination showing the characteristic membrane and a throat culture, or culture of other suspect lesions growing C. diphtheriae, confirm this diagnosis.
Treatment must not wait for confirmation by culture. Standard treatment includes diphtheria antitoxin administered I.M. or I.V.; antibiotics, such as penicillin or erythromycin, to eliminate the organisms from the upper respiratory tract and other sites and terminate the carrier state; measures to prevent complications; and possible tracheotomy if airway obstruction occurs.
Diphtheria requires comprehensive supportive care with psychological support.
❑To prevent the spread of this disease, stress the need for droplet precautions. Teach proper disposal of nasopharyngeal secretions. Maintain infection precautions until after two consecutive negative naso-pharyngeal cultures — at least 1 week after discontinuing drug therapy. Treatment of exposed individuals with antitoxin remains controversial. Suggest that the patient's family receive diphtheria toxoid if they haven’t been immunized.
❑Give drugs as ordered. Although time-consuming and risky, desensitization should be attempted if tests are positive, because diphtheria antitoxin is the only specific treatment available. If sensitivity tests are negative, the antitoxin is given before laboratory confirmation, because mortality increases directly with any delay in antitoxin administration. Before giving diphtheria antitoxin, which is made from horse serum, obtain eye and skin tests to determine sensitivity. After giving antitoxin or penicillin, be alert for anaphylaxis; keep epinephrine 1:1,000 and resuscitation equipment handy. In patients who receive erythromycin, watch for thrombophlebitis.
❑Monitor respirations carefully, especially in laryngeal diphtheria (usually, such patients are in a high-humidity environment). Watch for signs of airway obstruction, and be ready to give immediate life support, including intubation and tracheotomy.
❑Watch for signs of shock, which can develop suddenly.
❑Obtain cultures as ordered.
❑If neuritis develops, tell the patient it's usually transient. Be aware that peripheral neuritis may not develop until 2 to 3 months after the onset of illness.
Alert Be alert for signs of myocarditis, such as the development of heart murmurs or electrocardiogram changes. Ventricular fibrillation is a common cause of sudden death in patients with diphtheria.
❑Stress the need for childhood immunizations to all parents. Protective immunity doesn't last longer than 10 years after the last vaccination, so it's important to get tetanus-diphtheria boosters every 10 years.
❑Report all cases to local public health authorities.
Review other book chapters online related to Diphtheria:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
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