1. Strep or Sore Throat Slideshow Pictures
2. Take the MRSA Quiz!
3. Infectious Mononucleosis Slideshow Pictures

Medical Author:

Steven Doerr, MD

Steven Doerr, MD

Steven Doerr, MD, is a U.S. board-certified Emergency Medicine Physician. Dr. Doerr received his undergraduate degree in Spanish from the University of Colorado at Boulder. He graduated with his Medical Degree from the University Of Colorado Health Sciences Center in Denver, Colorado in 1998 and completed his residency training in Emergency Medicine from Denver Health Medical Center in Denver, Colorado in 2002, where he also served as Chief Resident.

View Full Profile

Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

View Full Profile

In this Article

• What is diphtheria?
• What is the history of diphtheria?
• What causes diphtheria?
• How is diphtheria transmitted?
• What are the signs and symptoms of diphtheria?
• How is diphtheria diagnosed?
• What is the treatment for diphtheria?
• What are the complications of diphtheria?
• How is diphtheria prevented?
• Diphtheria At A Glance
• Diphtheria Index

Diphtheria is transmitted to close contacts via airborne respiratory droplets or by direct contact with nasopharyngeal secretions or skin lesions. Rarely, it can be spread by objects contaminated by an infected person. Overcrowding and poor living conditions can further contribute to the spread of diphtheria.

Humans are the only known reservoir of Corynebacterium diphtheriae. Infected individuals may develop symptoms of diphtheria, or they may become carriers of the bacteria with no symptoms (asymptomatic carriers). These asymptomatic carriers can serve as reservoirs for active infection and may transmit the disease to other individuals.

The symptoms of respiratory diphtheria usually begin after a two- to five-day incubation period. Symptoms of respiratory diphtheria may include the following:

• sore throat,
• fever,
• malaise,
• hoarseness,
• difficulty swallowing, or
• difficulty breathing.

With the progression of respiratory diphtheria, the infected individual may also develop an adherent gray membrane (pseudomembrane) forming over the lining tissues of the tonsils and/or nasopharynx. Individuals with severe disease may also develop neck swelling and enlarged neck lymph nodes, leading to a "bull-neck" appearance. Extension of the pseudomembrane into the larynx and trachea can lead to obstruction of the airway with subsequent suffocation and death.

The dissemination of diphtheria toxin can also lead to systemic disease, causing complications such as inflammation of the heart (myocarditis) and neurologic problems such as paralysis of the soft palate, vision problems, and muscle weakness.

Cutaneous diphtheria is characterized by a non-healing skin ulcer covered by a gray-brown membrane. It is typically a localized infection that is rarely associated with systemic complications.