swelling and inflammation, and the individual may present with a “bulk neck” appearance (Vitek and Wharton, 2008).
While diphtheria in the respiratory tract is the most common manifestation, aural, conjunctival, cutaneous, and vaginal diphtheria can also occur and taken together account for approximately 2 percent of diphtheria cases (Vitek and Wharton, 2008).
The obvious consequences of diphtheria are manifested in the complications that arise from the presence and subsequent shedding of the membrane. In severe cases, the membrane may extend into the tracheo-bronchial tree causing pneumonia and expiratory respiratory obstruction and membrane aspiration (Vitek and Wharton, 2008). Other complications are caused by the effect of the absorbed diphtheria toxin on organs and organ systems proportional to the severity of the disease (Vitek and Wharton, 2008). Evidence of myocarditis has been found in up to 66 percent of patients with 10 to 25 percent developing clinically significant cardiac dysfunction (MacGregor, 2010). Neuropathy occurs rarely in mild disease but occurs in up to 75 percent of patients with severe diphtheria (MacGregor, 2010). Hypotension, pneumonia, and renal failure are also common in severe cases, while encephalitis and cerebral infarction has been described in rare cases (MacGregor, 2010). Death occurs most frequently within 3 to 4 days from disease onset and is most often caused by asphyxia or myocarditis (MacGregor, 2010).
Immunization with diphtheria toxoid has dramatically altered the epidemiology of diphtheria in the United States and data obtained from the 1988–1994 National Health and Nutrition Examination Survey (NHANES) III serosurvey indicated that 80 percent of persons age 12 to 19 years were immune to diphtheria (McQuillan et al., 2002).
The first vaccine against diphtheria was developed in the early 1800s and was widely used in the United States as early as 1914 (Vitek and Wharton, 2008). The vaccine consisted of a toxin-antitoxin formulation and was found to be 85 percent effective in preventing diphtheria (Vitek and Wharton, 2008). In the 1920s, Ramon found that by treating the toxin with formalin and creating the toxoid, the toxicity of the preparation could be reduced while maintaining the immunogenic properties (Vitek and Wharton, 2008). In 1926, Glenny and his associates discovered that alum-precipitated toxoid was even more effective, and by the mid-1940s diphtheria toxoid was being combined with tetanus toxoid and whole-cell pertussis vaccine to create the diphtheria-tetanus-pertussis (DTP) vaccine (Vitek and Wharton, 2008). Soon after, the DTP combination vaccine was adsorbed onto an aluminum salt and researchers noted the enhanced immunogenicity of the diphtheria and tetanus toxoid in the presence of pertussis vaccine and the aluminum salt (Vitek and Wharton, 2008).