Overview

Diphtheria is a serious bacterial infection caused by Corynebacterium diphtheriae. It primarily affects the mucous membranes of the throat and nose, though it can also infect the skin. The infection is highly contagious and can be life-threatening if left untreated.

Diphtheria is rare in developed countries due to widespread vaccination, but it remains a concern in regions with low immunization rates. According to the World Health Organization (WHO), there were 16,651 reported cases globally in 2018, though the actual number is likely higher due to underreporting.

The disease can affect people of all ages, but it is most common in children under 5 and adults over 60 who may not be fully immunized. Before the introduction of the diphtheria vaccine in the 1920s, the disease was a leading cause of childhood death.

Symptoms

Symptoms of diphtheria typically appear 2 to 5 days after exposure to the bacteria. The severity of symptoms can vary depending on the site of infection and the individual's immunization status.

Respiratory Diphtheria (Most Common Form)

• Sore throat: Often mild at first but can worsen, making swallowing painful.
• Gray or white membrane in the throat: A thick, grayish membrane may cover the throat and tonsils, which can bleed if disturbed. This is a hallmark sign of diphtheria.
• Fever and chills: Typically mild, around 101°F (38.3°C) or lower.
• Swollen glands (lymph nodes): Noticeable swelling in the neck, sometimes referred to as "bull neck" due to severe swelling.
• Hoarseness or cough: The voice may become raspy, and a barking cough (similar to croup) may develop.
• Difficulty breathing or rapid breathing: The membrane can obstruct the airway, leading to severe respiratory distress.

Cutaneous (Skin) Diphtheria

• Skin lesions or ulcers: Often painful, with a grayish membrane. Commonly found on the legs, feet, and hands.
• Redness and swelling: The surrounding skin may become inflamed.
• Sores that heal slowly: Unlike typical wounds, these may take weeks to heal and can leave scars.

Other Symptoms

• Fatigue and weakness: Generalized malaise is common.
• Nasal discharge: May be bloody or contain a grayish membrane if the nose is infected.
• Difficulty swallowing: Due to throat swelling or membrane obstruction.

In severe cases, diphtheria toxin can spread through the bloodstream, leading to systemic symptoms such as heart failure, nerve damage, or paralysis.

Causes and Risk Factors

Causes

Diphtheria is caused by the bacterium Corynebacterium diphtheriae. The bacteria produce a powerful toxin that damages tissues and can spread through the bloodstream, affecting organs such as the heart and nervous system.

The infection spreads through:

• Respiratory droplets (coughing or sneezing).
• Direct contact with infected skin lesions.
• Contact with contaminated objects (e.g., toys, cups, or tissues).

Risk Factors

Several factors increase the risk of contracting diphtheria:

• Lack of vaccination: Children and adults who haven’t received the diphtheria vaccine (part of the DTaP or Tdap series) are at highest risk.
• Travel to endemic areas: Regions with low vaccination rates, such as parts of Africa, Asia, the Middle East, and Eastern Europe, have higher diphtheria rates.
• Crowded or unsanitary conditions: Overcrowding in refugee camps, prisons, or homeless shelters can facilitate spread.
• Weakened immune system: Individuals with HIV/AIDS, malnutrition, or other immunocompromising conditions are more susceptible.
• Age: Children under 5 and adults over 60 are more vulnerable to severe infection.
• Close contact with an infected person: Household members or healthcare workers exposed to diphtheria patients are at higher risk.

Diagnosis

Diphtheria is diagnosed based on clinical symptoms, medical history, and laboratory tests. Early diagnosis is critical to prevent complications.

Medical History and Physical Exam

A healthcare provider will ask about:

• Vaccination status.
• Recent travel to areas with diphtheria outbreaks.
• Exposure to someone with diphtheria.

During the exam, the provider will look for:

• A grayish membrane in the throat or nose.
• Swollen lymph nodes in the neck.
• Signs of respiratory distress.

Laboratory Tests

• Throat or nose culture: A swab is taken from the throat or nose and sent to a lab to identify C. diphtheriae. Results may take 24–48 hours.
• Skin culture: If cutaneous diphtheria is suspected, a swab of the lesion is tested.
• Toxin testing: If the bacteria are detected, further tests (e.g., Elek’s test) confirm whether they produce the diphtheria toxin.
• Blood tests: May be done to assess complications like heart or nerve damage.

Note: Treatment often begins before lab results are confirmed if diphtheria is strongly suspected, as delays can be fatal.

Treatment Options

Diphtheria requires immediate medical treatment, often in a hospital setting. Treatment focuses on neutralizing the toxin, eliminating the bacteria, and managing complications.

1. Antitoxin Therapy

The most critical step is administering diphtheria antitoxin, which neutralizes the toxin circulating in the body. Key points:

• The antitoxin is derived from horse serum, so skin testing for allergies is done first.
• It is given as an injection (intravenously or intramuscularly).
• The antitoxin does not neutralize toxin already bound to tissues, so early treatment is essential.

2. Antibiotics

Antibiotics are used to kill the bacteria and stop toxin production. Common options include:

• Penicillin (intravenous or intramuscular).
• Erythromycin (oral or IV, especially for penicillin-allergic patients).

Antibiotics are typically given for 14 days. Patients are no longer contagious after 48 hours of antibiotic treatment.

3. Supportive Care

• Airway management: Severe throat swelling may require a breathing tube or tracheostomy.
• IV fluids: For dehydration or difficulty swallowing.
• Bed rest: To reduce strain on the heart, especially if myocarditis (heart inflammation) is present.
• Heart monitoring: ECG or other tests to detect cardiac complications.

4. Isolation

Patients are isolated in the hospital until they are no longer contagious (usually after 48 hours of antibiotics). Close contacts may also need antibiotics or a booster vaccine.

Living with Diphtheria

Recovery from diphtheria can take weeks, especially if complications arise. Here’s how to manage daily life during and after treatment:

During Recovery

• Follow medical advice: Complete the full course of antibiotics, even if symptoms improve.
• Rest: Avoid physical exertion, especially if heart complications are a concern.
• Hydration and nutrition: Eat soft foods (e.g., soups, yogurt) if swallowing is painful. Stay hydrated with water, broth, or electrolyte drinks.
• Monitor for complications: Watch for signs of heart problems (irregular heartbeat, chest pain) or nerve damage (muscle weakness, difficulty swallowing).
• Avoid spreading infection: Wash hands frequently, cover coughs/sneezes, and avoid close contact with others until cleared by a doctor.

After Recovery

• Vaccination: Ensure you and your family are up to date on diphtheria vaccines (DTaP for children, Tdap for adults).
• Follow-up appointments: Attend all scheduled check-ups to monitor for long-term complications like heart or nerve damage.
• Rehabilitation: Physical therapy may be needed if muscle weakness or paralysis occurs.

Prevention

Vaccination is the most effective way to prevent diphtheria. The vaccine is typically combined with tetanus and pertussis (whooping cough) vaccines.

Vaccination Schedule

• Children:
  • DTaP vaccine: Given at 2, 4, 6, and 15–18 months, with a booster at 4–6 years.
• Adolescents and Adults:
  • Tdap booster: Given at age 11–12, then every 10 years with the Td (tetanus-diphtheria) vaccine.
• Special Cases:
  • Travelers to endemic areas may need an additional booster.
  • Healthcare workers or those exposed to diphtheria should ensure their vaccinations are current.

Other Preventive Measures

• Good hygiene: Wash hands regularly with soap and water.
• Isolate infected individuals: Prevent spread by isolating patients until they are no longer contagious.
• Public health measures: Outbreaks require swift action, including contact tracing and prophylactic antibiotics for exposed individuals.

Note: Vaccination does not guarantee 100% protection, but it significantly reduces the risk of severe disease.

Complications

If untreated, diphtheria can lead to severe, sometimes fatal, complications. The diphtheria toxin can damage multiple organs, including the heart, nerves, and kidneys.

Common Complications

• Myocarditis: Inflammation of the heart muscle, which can lead to heart failure or arrhythmias. Occurs in up to 20% of cases and is a leading cause of death.
• Neuropathy: Nerve damage causing muscle weakness or paralysis. May affect the throat (difficulty swallowing), limbs, or diaphragm (breathing difficulties).
• Airway obstruction: The thick membrane can block the airway, leading to suffocation if not treated promptly.
• Kidney damage: Toxin-induced inflammation can impair kidney function.
• Respiratory failure: Severe cases may require mechanical ventilation.

Long-Term Effects

• Permanent heart damage or chronic heart failure.
• Persistent muscle weakness or paralysis (though most nerve damage is reversible over months).
• Scarring from skin lesions (in cutaneous diphtheria).

According to the CDC, even with treatment, diphtheria has a fatality rate of 5–10%, which rises to 20% in children under 5 and adults over 40.

When to Seek Emergency Care

Sources and Further Reading

• Centers for Disease Control and Prevention (CDC): Diphtheria
• World Health Organization (WHO): Diphtheria
• Mayo Clinic: Diphtheria
• Cleveland Clinic: Diphtheria
• National Institutes of Health (NIH): Diphtheria