Diphtheria
A serious vaccine-preventable bacterial infection of the throat and skin
Quick Facts
- Type: Bacterial infection
- Cause: Corynebacterium diphtheriae toxin
- Spread: Respiratory droplets, skin contact
- Prevention: Diphtheria vaccine (part of DTaP/Tdap)
Overview
Diphtheria is a serious infection caused by bacteria called Corynebacterium diphtheriae. The bacteria can release a powerful toxin that damages tissues and, in the respiratory form, creates a thick gray membrane in the throat that can block breathing. The toxin can also travel through the body and harm the heart, nerves, and kidneys.
Once a common and feared childhood illness, diphtheria has become rare in countries with routine vaccination. It still occurs where immunization coverage is low or has lapsed. Because it can be life-threatening, diphtheria is treated as a medical emergency, and protection through vaccination remains very important.
Symptoms
Respiratory diphtheria usually begins 2 to 5 days after exposure. Symptoms may include:
- Sore throat and hoarseness
- A thick gray or white coating over the throat and tonsils
- Difficulty swallowing or breathing
- Swollen glands giving a 'bull neck' appearance
- Mild fever and weakness
- A barking cough or noisy breathing
Diphtheria of the skin (cutaneous diphtheria) causes ulcers or sores, often with a gray covering. Trouble breathing, a covering over the throat, or a child who is struggling to breathe require emergency care.
Causes
Diphtheria is caused by toxin-producing strains of Corynebacterium diphtheriae bacteria. The illness spreads from person to person in several ways:
- Respiratory droplets: Coughing and sneezing release bacteria that others breathe in.
- Close contact: Sharing living spaces or touching infected secretions.
- Contaminated objects: Less commonly, items touched by an infected person.
- Skin contact: Touching the sores of someone with cutaneous diphtheria.
The bacteria make a toxin that destroys nearby tissue and can spread to vital organs.
Risk Factors
- Not being vaccinated or not keeping up with booster doses
- Living in or traveling to areas with low vaccination coverage or active outbreaks
- Crowded or unsanitary living conditions
- A weakened immune system
- Close contact with an infected person
Diagnosis
Doctors often suspect diphtheria from the characteristic throat membrane and the person's vaccination and travel history. To confirm it they may use:
- Throat or skin swab: A sample is sent to a laboratory to grow and identify the bacteria.
- Toxin testing: Special tests determine whether the strain produces the dangerous toxin.
Because delay can be deadly, treatment is usually started based on strong clinical suspicion before laboratory results return.
Treatment
Diphtheria is treated urgently in a hospital, often with isolation to prevent spread. The main treatments are:
- Diphtheria antitoxin: A medicine that neutralizes the toxin still circulating in the body; it works best when given early.
- Antibiotics: Such as penicillin or erythromycin to kill the bacteria and stop the person from spreading it.
- Airway support: Careful monitoring and, if needed, help keeping the airway open if the throat membrane threatens breathing.
- Supportive care: Rest, fluids, and monitoring of the heart and nerves for toxin-related complications.
Close contacts are checked, treated with preventive antibiotics, and offered vaccination as needed.
Prevention
Vaccination is the cornerstone of prevention and has made diphtheria rare where it is widely used:
- Childhood vaccination, given in combination shots such as DTaP
- Booster doses for adolescents and adults (Tdap and Td) every 10 years
- Catch-up vaccination for anyone who is behind on doses
- Prompt evaluation and preventive treatment for close contacts of a case
- Good hygiene and avoiding close contact with infected people
When to See a Doctor
See a doctor promptly for a severe sore throat with a gray throat coating, especially if you are not up to date on vaccines or have traveled to an outbreak area. Seek emergency care immediately if you or your child has:
- Trouble breathing or noisy, labored breathing
- Difficulty swallowing
- Bluish skin or lips
- Severe neck swelling
Frequently Asked Questions
Is diphtheria still a threat today?
Diphtheria has become rare in countries with strong vaccination programs, but it still occurs where immunization coverage is low or has dropped. Outbreaks can happen, and unvaccinated travelers are at risk. Keeping up with vaccines remains the best protection.
How does the diphtheria vaccine work?
The vaccine teaches the immune system to neutralize the diphtheria toxin, which is what causes the most dangerous effects of the infection. It is given in childhood combination shots like DTaP and boosted in adolescence and adulthood with Tdap or Td. Boosters are recommended every 10 years.
Why is diphtheria dangerous?
The bacteria release a toxin that can form a thick membrane blocking the airway and can also damage the heart, nerves, and kidneys. Without prompt antitoxin and antibiotics, these effects can be fatal. This is why diphtheria is treated as an emergency.
How is diphtheria spread?
It spreads mainly through respiratory droplets when an infected person coughs or sneezes, and through close contact or contact with the sores of skin diphtheria. Crowded conditions and low vaccination rates make spread more likely. Isolating cases and treating contacts helps stop outbreaks.
What should I do if exposed to diphtheria?
Tell a doctor right away if you have been near someone with diphtheria, especially if you are not fully vaccinated. Close contacts are usually monitored, given preventive antibiotics, and offered a vaccine booster. Watch closely for sore throat, fever, or trouble breathing.
References
- Centers for Disease Control and Prevention (CDC). Diphtheria.
- World Health Organization (WHO). Diphtheria.
- MedlinePlus, U.S. National Library of Medicine. Diphtheria.
- Mayo Clinic. Diphtheria.