Diphtheria: Causes, Symptoms, Outbreaks, Treatment, Management & Prevention

Diphtheria is a serious, contagious and potentially fatal bacterial infection. It usually affects the nose and throat, where it can produce a thick grey membrane that obstructs breathing.

The bacteria can also infect the skin and release a powerful toxin capable of damaging the heart, nerves and other organs.

Although diphtheria is preventable through vaccination and has become uncommon in countries with strong immunisation programmes, it has not been eradicated.

What is Diphtheria?

Diphtheria is an acute infectious disease caused mainly by toxin-producing strains of the bacterium Corynebacterium diphtheriae. The infection primarily affects the upper respiratory tract, including the nose, throat, tonsils and larynx.

It may also cause skin infections known as cutaneous diphtheria. 

The most dangerous effects of diphtheria are caused by an exotoxin released by toxigenic bacteria.

This toxin damages tissues at the site of infection and can enter the bloodstream, where it may injure the heart, peripheral nerves and kidneys.

The name “diphtheria” comes from the Greek word diphthera, meaning “leather hide.” It refers to the thick, tough pseudomembrane that may form over the throat and tonsils.

What bacteria cause Diphtheria?

The principal cause of classical diphtheria is toxigenic Corynebacterium diphtheriae. It is an aerobic, Gram-positive, non-spore-forming bacillus.

note:- Not every strain of C. diphtheriae produces diphtheria toxin. The bacterium becomes toxigenic when it is infected by a specific virus called a corynebacteriophage that carries the tox gene.

This gene enables the bacterium to produce diphtheria toxin.

*Humans are the main reservoir of C. diphtheriae. Both symptomatic patients and people carrying the bacteria without obvious symptoms can transmit it.

How does Diphtheria spread?

Diphtheria usually spreads from person to person through:

• Respiratory droplets released during coughing, sneezing or close conversation.
• Direct contact with saliva or respiratory secretions.
• Direct contact with infected wounds or skin ulcers.
• Less commonly, contact with objects contaminated by discharge from an infected lesion.

Living in the same household, regularly sharing a confined space or having direct contact with secretions from an infected person increases the risk of transmission.

Crowding, population displacement, poor access to healthcare and low vaccination coverage can accelerate outbreaks.

The usual incubation period is two to five days, although symptoms may appear between one and ten days after exposure.

Symptoms of Diphtheria

Usually, symptoms most commonly begin two to five days after exposure.

Example - early respiratory diphtheria can resemble an ordinary sore throat. Hence, making clinical awareness is important.

Early symptoms

• Sore throat
• Mild fever
• Weakness and fatigue
• Loss of appetite
• Pain or difficulty when swallowing
• Swollen glands in the neck
• Nasal discharge, sometimes blood-stained
• Hoarseness or change in voice

Characteristic respiratory symptoms

Hence, As the infection progresses, a patient may develop:

• A thick grey, white or dirty-looking membrane over the tonsils, throat or nose
• Increasing difficulty swallowing
• Noisy breathing
• Shortness of breath
• Severe swelling of the neck, sometimes called a “bull neck”
• Signs of airway obstruction

The pseudomembrane is a major warning sign. It is tightly attached to the underlying tissue and should not be forcibly removed by an untrained person.. .

How is diphtheria diagnosed?

Diphtheria is initially a clinical diagnosis. Because delayed treatment increases the risk of complications and death, clinicians should not wait for laboratory confirmation before treating a strongly suspected case.

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