Diphtheria is a life-threatening bacterial illness prevented by vaccination. Unimmunized children under the age of 15 are most susceptible. Initial symptoms are skin lesions or pseudomembranous pharyngitis followed by exotoxin-induced myocardial and neural damage.

5 (US); 7,000 (Global)
Corynebacterium diphtheriae infection;
2-5 days (range of, 1-10 days); [CDC Travel]
Sore throat, low-grade fever, dysphagia, membrane in tonsillar area ("dirty gray, tough, fibrinous, and adherent"); [Merck Manual] Gradual onset of fever, difficulty swallowing, & hoarseness if larynx involved; Membrane appears on days 2-3; [CDC Travel]
Contact for cutaneous diphtheria & droplet for pharyngeal diphtheria "Until two cultures taken 24 hrs. apart negative." [CDC 2007 Guideline for Isolation Precautions] "The rare chronic carrier may shed organisms for 6 months or more. Effective antibiotic therapy promptly terminates shedding." [CCDM, p. 152]
Swelling of the neck may give patients a "bull neck" appearance. The main complications of diphtheria are airway obstruction, myocarditis, and neuropathy. Myocarditis, usually first detected by EKG about 7-14 days after disease onset, can cause severe conduction abnormalities and death. Neuropathy may begin with palatal weakness and later progress to cranial nerve palsies and paralysis of the diaphragm and extremities. Other complications of severe disease include thrombocytopenia, acute renal failure, and disseminated intravascular coagulation. [Guerrant, p. 224-5] A potent toxin, produced by the growing bacteria, injures the nerves, heart, and kidneys. Neuropathy of some kind develops in about 15% of untreated patients and in about 75% of patients with severe disease. A polyneuropathy, resembling Guillain-Barre syndrome, is delayed in onset and usually appears about 2-3 months after onset of the illness. Patients with skin lesions may act as chronic carriers, but do not usually suffer from the toxic manifestations of the disease. Patients with nasal diphtheria have blood-tinged discharge and also may act as carriers [ID, p. 1339, 1625] Cutaneous diphtheria may begin as a blister or pustule that progresses to an ulcer, usually on an extremity. [Guerrant, p. 225] Toxic complications are rare in cutaneous diphtheria because the toxin in poorly absorbed through the skin. [Merck Manual, p. 1612] Patients with obstructive laryngotracheitis caused by the membrane have hoarseness, cough, and dyspnea. [5MCC-2020] Infection is fatal in about 4% to 12% of cases. Death usually occurs in the first 3-4 days, and it is caused by asphyxiation or myocarditis. Pharyngitis, fever, and dysphagia are the most common symptoms. A membrane and cervical lymphadenopathy are observed in only about 1/2 of patients. Peripheral neuritis becomes manifest as weakness or paralysis from 10 days to 3 months after the primary throat infection. Invasive disease (endocarditis, osteomyelitis, and arthritis) caused by nontoxigenic strains has been recently described. Drug addicts and alcoholics are at increased risk. [PPID, 8th Ed, p. 2369-70] Neurological complications in the first 2 weeks include dysphagia and cranial nerve effects (weakness of tongue, facial numbness, and blurred vision). [Harrisons, p. 461]

Only 18 cases were reported in the USA between 1980 and 1994. Transmission occurs by contact with infected patients through respiratory droplets or skin lesions. [Guidelines for Infection Control in Health Care Personnel. CDC. 1998] Unimmunized children under the age of 15 are most susceptible. Outbreaks in recent years occurred in Ecuador and countries of the former Soviet Union. Transmission by raw milk has been reported. [CCDM, p. 151] Patients with cardiac involvement have a poor prognosis. A 30-40% mortality rate is associated with bacteremia. [Gorbach, p. 153] Severe corneal involvement can result in scarring and blindness. [ID, p. 1625]
Clinical--treat if suspected; Culture (selective media required); [ID, p. 1339] Test all C. diphtheria strains isolated for toxigenicity. [Cecil, p. 1882] A rapid method available in some labs: IFA staining of a 4-hour culture; [ABX Guide: C. diphtheriae]
Global: Endemic in many areas of South America, Asia, the South Pacific, the Middle East, and Eastern Europe; Also in Haiti and the Dominican Republic; [CDC Travel]
  • >fatigue, weakness
  • >fever
  • E dysphagia
  • E epistaxis
  • E nasal ulcers
  • E pharyngitis
  • E rhinitis
  • H leukocytosis
  • H lymphadenopathy
  • H thrombocytopenia
  • N headache
  • N muscle weakness
  • O conjunctivitis, acute
  • O oculoglandular syndrome
  • R cough
  • R dyspnea
  • S pustule
  • S skin blister or vesicles
  • S ulcer of skin
  • *acute renal failure
  • *arthritis
  • *bleeding tendency
  • *blindness
  • *cranial neuropathy
  • *encephalitis
  • *endocarditis
  • *erythema nodosum
  • *myocarditis
  • *osteomyelitis
  • *paralysis
  • *peripheral neuropathy
  • *pneumonia
  • *shock




Inhalation, Ingestion, Skin or Mucous Membranes (Includes Conjunctiva)
Person-to-Person, Eating Contaminated Food, Eating Unpasteurized Milk or Cheese
  • Care for patients (droplet/airborne)
  • Consume unpasteurized milk/cheese
  • Fail to complete immunizations
  • Injection drug users
  • Live together in close quarters
  • Travel to endemic area
1. (US) Average of 21,000 case/year in prevaccine era; One case reported in 2012; [Harrison ID, p. 49t] Guesstimate = 5;
2. (Global) WHO estimated about 7000 cases in 2008 and 5000 deaths in 2004; [Harrison ID, p. 444]