• Diphtheria is caused by toxin-producing bacteria, Corynebacterium diphtheriae, and less frequently by one of two other, zoonotic, Corynebacteria.
  • Diphtheria toxin destroys tissue, which builds up in the throat and tonsils, making breathing and swallowing almost impossible.
  • The bacteria are transmitted by respiratory droplets, by direct physical contact with skin lesions, via secretions from infected patients, or contaminated materials.
  • Clinically, tonsillitis, pharyngitis, laryngitis, and skin infections (wound infection; ulcers) appear;  diphtheria once was a terrible killer of young children.
  • Antibiotics (penicillin, erythromycin, others) are used to eradicate the bacteria; for respiratory infections, diphtheria antitoxin is used to neutralize circulating toxins and reduce/prevent complications like myocarditis, neuritis (nerve palsies).
  • Case fatality rates of up to 10% have been reported during diphtheria outbreaks, and are even higher in settings where diphtheria antitoxin is unavailable.
  • Diphtheria vaccines consist of inactivated toxins, called toxoids, and are available in combinations with other antigens such as tetanus, pertussis, and others.
  • These combinations are usually well-tolerated, local reactions are the most frequently observed side effects.
  • Efficacy studies are not available but various observational studies consistently indicate high vaccine effectiveness between 87% and 96%.