Respiratory diphtheria in the United States, 1980 through 1995

The purpose of this study was to describe the epidemiologic, laboratory, and clinical features of respiratory diphtheria cases reported in the United States during 1980 through 1995. Respiratory diphtheria cases reported to the Centers for Disease Control and Prevention were reviewed. Cases were defined as physician-diagnosed cases with signs and symptoms compatible with respiratory diphtheria, including the presence of a pseudomembrane without other apparent cause. From 1980 through 1994, 41 respiratory diphtheria cases were reported; none were reported in 1995, and no secondary cases were identified. Nine (22%) case patients were 4 years of age or younger, and 28 (68%) were 15 years of age or older. None of the case patients were up to date with diphtheria vaccination; 4 unvaccinated children died. Seventeen (43%) of 40 case patients had positive culture results. Available surveillance data suggest that respiratory diphtheria has become a rare disease in the United States. However, importation and circulation of toxigenic strains continue to present a threat and require achieving and maintaining high coverage with diphtheria toxoid-containing vaccines in both children and adults.