History
Respiratory diphtheria symptoms typically follow an incubation period of 2-5 days (range, 1-10 d). [2, 11] Symptoms initially are general and nonspecific, often resembling a typical viral upper respiratory infection (URI). Respiratory involvement usually begins with sore throat and mild pharyngeal inflammation. Development of a localized or coalescing pseudomembrane can occur in any portion of the respiratory tract. The pseudomembrane (shown below) is characterized by the formation of a dense, gray debris layer composed of a mixture of dead cells, fibrin, RBCs, WBCs, and organisms.
The characteristic thick membrane of diphtheria infection in the posterior pharynx.
Removal of the membrane reveals a bleeding, edematous mucosa. The distribution of the membrane varies from local (eg, tonsillar, pharyngeal) to widely covering the entire tracheobronchial tree. The membrane is intensely infectious, and droplet and contact precautions must be followed when examining or caring for infected patients. A combination of cervical adenopathy and swollen mucosa imparts a "bull's neck" appearance to many of the infected patients (shown below). The most frequent cause of death is airway obstruction or suffocation following aspiration of the pseudomembrane. [19]
Cervical edema and cervical lymphadenopathy from diphtheria infection produce a bull's neck appearance in this child. Source: Public Domain www.immunize.org/images/ca.d/ipcd1861/img0002.htm.
Cutaneous diphtheria is characterized by indolent, nonhealing ulcers covered with a gray membrane. The ulcers often are co-infected with Staphylococcus aureus and group A streptococci. This form of the disease is seen with increasing frequency in poor inner-city dwellers and alcoholics. The lesions of cutaneous diphtheria are infectious, and bacteria from cutaneous lesions have been found to cause pharyngeal infections and thus serve as a reservoir for infection.
Patients with diphtheria may present with the following complaints:
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Low-grade fever (rarely >103°F) (50-85%) and chills
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Malaise, weakness, prostration
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Sore throat (85-90%)
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Headache
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Cervical lymphadenopathy and respiratory tract pseudomembrane formation (about 50%)
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Serosanguineous or seropurulent nasal discharge, white nasal membrane
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Hoarseness, dysphagia (26-40%)
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Dyspnea, respiratory stridor, wheezing, cough
Respiratory diphtheria may quickly progress to respiratory failure due to airway obstruction or aspiration of pseudomembrane into the tracheobronchial tree.
Cutaneous diphtheria often develops at a site of previous trauma or a primary dermatologic disease. It follows an indolent course, typically lasting weeks to months. Occasionally, it may cause respiratory diphtheria. [19]
Physical
General: Patient has a low-grade fever but is toxic in appearance, and also may have a swollen neck.
Pharyngeal diphtheria:
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Patients may present with general symptoms of fever, halitosis, tachycardia, and anxiety.
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Tonsils and pharynx: Pharyngeal erythema and edema; thick, gray, leathery membrane variably covers the tonsils, soft palate, oropharynx, nasopharynx, and uvula. Attempts at scraping the pseudomembrane cause bleeding of the underlying mucosa.
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Neck: Extensive anterior and submandibular cervical lymphadenopathy imparts a bull's neck appearance. The patient may hold his or her head in extension. It occasionally can also be associated with dysphonia.
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Respiratory distress manifesting as stridor, wheezing, cyanosis, accessory muscle use, and retractions.
Cardiac toxicity typically occurs after 1-2 weeks of illness following improvement in the pharyngeal phase of the disease. It may manifest as follows:
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Myocarditis is seen in as many as 60% of patients (especially if previously unimmunized) and can present acutely with congestive heart failure (CHF), circulatory collapse, or more subtly with progressive dyspnea, diminished heart sounds, cardiac chamber dilatation, and weakness. [21]
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Atrioventricular blocks, ST-T wave changes, and various dysrhythmias may be evident.
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Endocarditis may be present, especially in the presence of an artificial valve. [22]
Neurologic toxicity is proportional to the severity of the pharyngeal infection. Most patients with severe disease develop neuropathy. Deficits include the following:
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Cranial nerve deficits including oculomotor, ciliary paralysis, facial, and pharyngeal, or laryngeal nervous dysfunction.
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Occasionally, a stocking and glove peripheral sensory neuropathy pattern can be observed.
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Most C diphtheriae associated neurologic dysfunction eventually resolves.
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Peripheral neuritis develops anywhere from 10 days to 3 months after the onset of pharyngeal disease. It manifests initially as a motor defect of the proximal muscle groups in the extremities extending distally. Various degrees of dysfunction exist, ranging from diminished DTRs to paralysis. [23]
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Other systems involvement: Diphtheria is occasionally seen in the female genital tract, conjunctivae, or ear.
Causes
The following factors may predispose to diphtheria infection:
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Incomplete or absent immunization, which is especially important in the adult population, and the pediatric population in underdeveloped countries, may predispose to infection. In some cases, immunity does not prevent infection but lessens the severity of the disease. [11]
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Antitoxin titers decrease over time and immunity wanes, thus older people who have not received booster vaccination are more susceptible to contract the disease from carriers. Studies suggest if titer level is greater than 0.1 UI/mL, an individual is characterized as immune from infection.
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Low herd immunity, possibly leading to increasing prevalence of diphtheria infections
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Travel to endemic areas or regions with current epidemics
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Immunocompromised states - Due to pharmacologic immune suppression, disease states including HIV, or relative compromise such as from diabetes or alcoholism
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Low socioeconomic status
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Large-scale population movements - Implicated in the spread of the epidemic in the Newly Independent States of the former Soviet Union [24]
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Poor healthcare care system infrastructure
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Overcrowding - Military barracks, homeless shelters, jails
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Domestic animals such as cats may act as reservoir for human infection. [16]
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The characteristic thick membrane of diphtheria infection in the posterior pharynx.
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Cervical edema and cervical lymphadenopathy from diphtheria infection produce a bull's neck appearance in this child. Source: Public Domain www.immunize.org/images/ca.d/ipcd1861/img0002.htm.
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Photomicrograph depicts a number of gram-positive Corynebacterium diphtheriae bacteria, which had been stained using the methylene blue technique. The specimen was taken from a Pai's slant culture.
