| Clinical Features |
Respiratory diphtheria presents as a sore throat with low-grade fever and an adherent pseudomembrane of the tonsils, pharynx, or nose. Neck swelling is usually present in severe disease. Cutaneous diphtheria presents as infected skin lesions which lack a characteristic appearance. |
| Etiologic Agent |
Toxin-producing strains of Corynebacterium diphtheriae. Toxin- producing strains of Corynebacterium ulcerans can also cause a diphtheria-like illness. |
| Incidence |
A confirmed case has not been reported in the U.S. since 2003. Approximately 0.001 cases per 100,000 population in the U.S. since 1980; before the introduction of vaccine in the 1920s incidence was 100-200 cases per 100,000 population. Diphtheria remains endemic in developing countries with low vaccination coverage. During the 1990s, the countries of the former Soviet Union reported >150,000 cases in a large epidemic. |
| Complications |
Myocarditis, polyneuritis, and airway obstruction are common complications of respiratory diphtheria; death occurs in 5%-10% of respiratory cases. Complications and deaths occur less frequently from cutaneous diphtheria. |
| Transmission |
Direct person- to-person transmission by contact with respiratory secretions and cutaneous lesions. Cutaneous lesions are important in transmission particularly in countries warm climates. |
| Risk Groups |
In the pre-vaccine era, children were at highest risk for respiratory diphtheria. Sporadic cases are more likely to occur among adults due to waning immunity and because of sustained high vaccine coverage for children in the U.S. Unvaccinated or inadequately vaccinated persons who travel to countries where diphtheria is endemic are at increased risk |
| Surveillance |
National surveillance through the National Notifiable Disease Surveillance System (NNDSS). Cases are also identified by requests for diphtheria antitoxin (DAT); since 1997 DAT is available for U.S. providers only through CDC. Click here for more information about DAT suppliers. |
| Trends |
Respiratory diphtheria is a rare disease in the U.S. (prior to 2003, 0-5 cases per year; no reported cases since 2003) In the pre-vaccine era, younger children were most often affected; in the post-vaccine era, an increasing proportion of cases has occurred among older children and adults. |
| Challenges |
Circulation appears to continue in some settings even in populations with >80% childhood immunization rates. An asymptomatic carrier state exists even among immune individuals.
Immunity wanes over time; decennial booster doses are required to maintain protective antibody levels. Large populations of older adults may be susceptible to diphtheria in developed countries as well as in developing countries.
In countries with low incidence, the diagnosis may not be considered by clinician and laboratory scientists. Prior antibiotic treatment can prevent recovery of the organism.
Limited epidemiologic, clinical, and laboratory expertise on diphtheria. |
| Opportunities |
New molecular typing methods allow for characterization of strains and closely related groups (clones) of strains. Will facilitate epidemiologic studies and possibly identification of other virulence factors.
Diphtheria antitoxin is available in the United States only through CDC; this should improve the reporting of suspected diphtheria cases. |
