What is diptheria?

Diphtheria is an infection caused by a bacterium (germ) called Corynebacterium diphtheriae.  These germs are not commonly found in Canada.  Diphtheria is an infection prevented through immunization.  Travellers and unimmunized persons are most at risk of getting sick.

Some people can carry the bacteria without it causing them any harm.  This is known as “colonization”.  The bacteria can cause infection in others. 

What are the symptoms of diphtheria?

Symptoms depend on which parts of the body the germs affect.  The germs mostly involves the upper respiratory tract (nose, tonsils, throat), but can affect the skin, eyes, or ears.

  • Fever
  • Tiredness
  • Bloody nasal discharge (snot)
  • Sore throat
  • Loss of appetite
  • Uneven white coating on the throat.  This coating can spread and make it difficult to breathe or swallow.
  • Neck swelling and larger lymph nodes, like a bull’s neck
  • Can cause serious problems with your heart and nerves.

Some people may not have any symptoms at all or symptoms may be mild.  It often takes about 2 to 5 days after the germs enter your body before you feel sick.

Photo of a woman rubbing her throat

How does diphtheria spread?

Diphtheria spreads mostly from person to person by:

  • Breathing in contaminated air from a person with the germs who is sneezing, coughing or speaking.
  • Touching the fluid of infected sores, and then touching your eyes, nose, or mouth.

People colonized with the bacteria can still spread the germs to others.  Babies born to immunized mothers are usually protected up to 6 months after birth.

How long is it contagious?

A person can infect others for as long as the germs are present in their sores and nasal/throat discharges.  If untreated, this can be for 2 to 6 weeks.  If treated with the right antibiotics (medications that kill or stop the growth of bacteria), a person is not contagious after 48 hours of treatment.

How is diphtheria treated?

If you or your child has these symptoms, see a health care provider as soon as possible.  Treatment may include antibiotics, an antitoxin (medications that fight the toxins made by the bacteria), and immunization.

How do I prevent the spread of diphtheria?

  • Getting the disease may not protect you from getting sick again.  The best way to prevent diphtheria is to get immunized against the diphtheria toxin.  The diphtheria vaccine is free as part of the Ontario’s publicly funded program.  Your body’s ability to fight the germs can decrease over time, so it is important to get the free vaccine every 10 years after the initial series.
  • Clean and disinfect contaminated linen and surfaces as soon as possible.
  • Follow these other tips to avoid getting sick.
Photo of a baby being vaccinated

For more information contact the Health Unit or speak to your health care provider.


American Academy of Pediatrics. (2018). Red book: 2018-2021 Report of the committee on infectious diseases (31st ed.). D.W. Kimberlin, M.T. Brady, M.A. Jackson, & S.S. Long (Eds.). Itasca, IL.

Heymann, D.L. (Ed.). (2015). Control of communicable diseases manual (20th ed.). Washington, DC: American Public Health Association.

Ontario Ministry of Health and Long-Term Care. (2018). Infectious Diseases Protocol: Appendix A – Diphtheria. Toronto, ON: Queen’s Printer for Ontario.