Diphtheria

Diphtheria disease is a potentially life-threatening infection caused by the bacterium Corynebacterium diphtheriae. Although it was once a major cause of illness and death among children, diphtheria is now rare in many parts of the world due to widespread vaccination. However, outbreaks can still occur, especially in areas with low vaccination rates. This detailed guide will provide you with comprehensive information about diphtheria, empowering you to protect yourself and your loved ones.

Diphtheria is an acute, toxin-mediated disease caused by the bacterium Corynebacterium diphtheriae. The bacteria usually infect the nose and throat, leading to the formation of a thick, grey membrane at the back of the throat. This membrane can make it difficult to breathe and swallow. The diphtheria toxin can also damage other organs, including the heart and nerves.

Diphtheria cases have significantly decreased globally due to vaccination efforts. However, it remains a concern in countries with low vaccination rates. 

In 2020, India reported 1,586 cases of diphtheria and 22 deaths, and in 2021, 3,677 cases and 47 deaths. 

The South-East Asia region has reported most of the global diphtheria incidence each year since 2000. India, Nepal, and Indonesia have reported 96%–99% of the cases in the region since 2000.

There are several types of diphtheria, classified based on the site of infection and the severity of the disease:

• Respiratory diphtheria: This is the most common type, affecting the nose, throat, and tonsils.
• Cutaneous diphtheria: This type affects the skin, causing sores and ulcers.
• Nasal diphtheria: This type affects the nasal passages.

Diphtheria is caused by the bacterium Corynebacterium diphtheriae. This bacterium produces a toxin that damages healthy tissues in the body, particularly the heart and nervous system.

Here's how this bacteria spreads:

Respiratory droplets

This is the most common mode of transmission. When an infected person coughs, sneezes, or even talks, they release tiny droplets containing the bacteria into the air. Inhaling these droplets can lead to infection.

Direct contact

Another cause of diphtheria is direct contact with the skin sores of an infected person. This is more common with cutaneous diphtheria.

Contaminated objects

Although less common, it's possible to contract diphtheria by touching objects (like toys, utensils, or bedding) that have been contaminated with the bacteria.

Diphtheria symptoms usually begin 2 to 5 days after exposure and can vary depending on the site of infection. Common symptoms include:

• Thick, grey membrane at the back of the throat: This is a hallmark sign of respiratory diphtheria. The membrane can cover the tonsils, uvula, and soft palate, making it difficult to breathe and swallow.
• Sore throat: A sore throat is often one of the first symptoms of diphtheria.
• Fever: Fever is common with diphtheria, but it may not be very high.
• Swollen lymph nodes in the neck: The lymph nodes in the neck may become swollen and tender.
• Difficulty breathing or swallowing: As the membrane grows, it can obstruct the airway, causing difficulty breathing. Swallowing can also become painful and difficult.
• Nasal discharge: With nasal diphtheria, there may be a foul-smelling nasal discharge.
• Skin sores: Cutaneous diphtheria causes sores and ulcers on the skin. These sores may be painful and slow to heal.

Diagnosing diphtheria involves a combination of a thorough clinical evaluation and specific laboratory tests to confirm the presence of the bacteria and its toxin. Here's a closer look at the process:

Physical examination

• Visual inspection: The doctor will carefully examine the patient's throat and nasal passages. In respiratory diphtheria, a hallmark sign is the presence of a thick, grey membrane covering the tonsils, uvula, and back of the throat. This membrane, called a "pseudomembrane," is tough and fibrous, and attempts to remove it may cause bleeding.
• Lymph node palpation: The doctor will also feel for swollen lymph nodes in the neck, which is a common symptom of diphtheria.
• Other signs: The doctor will assess the patient for other signs of illness, such as fever, difficulty breathing, and signs of distress.

Medical history

• Symptoms: The doctor will inquire about the patient's symptoms, including when they started, their severity, and any associated complaints.
• Vaccination status: It's crucial to determine the patient's vaccination history. Knowing whether they have received the diphtheria vaccine and when they received their last booster shot helps assess their risk.
• Recent exposures: The doctor will ask about any recent contact with individuals who have been sick, especially if there is a known case of diphtheria. Travel history to areas where diphtheria is more common is also important.

Laboratory tests

Throat swab culture

• Collection: A sterile swab is used to collect a sample from the back of the throat, including the surface of the pseudomembrane if present.
• Culture: The swab is then placed in a special transport medium and sent to a laboratory. There, the sample is streaked onto a culture media that encourages the growth of Corynebacterium diphtheriae.
• Identification: If the bacteria grow, they are further examined under a microscope and subjected to biochemical tests to confirm their identity as Corynebacterium diphtheriae.

Toxin test

• Elek test: This is a common test used to determine if the isolated Corynebacterium diphtheriae strain is producing the diphtheria toxin. It involves growing the bacteria on a special agar plate with an antitoxin strip. If the bacteria produce toxin, a visible line of precipitation will form where the toxin and antitoxin meet.
• PCR (Polymerase Chain Reaction): PCR can be used to detect the gene that codes for the diphtheria toxin in the bacteria. This is a rapid and sensitive method for identifying toxigenic strains.

Electrocardiogram (ECG)

• Heart assessment: An ECG is often performed to assess the heart's electrical activity. The diphtheria toxin can affect the heart muscle, and an ECG can help detect early signs of myocarditis (inflammation of the heart muscle) or other heart abnormalities.

Complete blood count (CBC)

• General health check: A CBC may be done to check for signs of infection, such as an elevated white blood cell count. It can also provide information about the patient's overall health status.

By combining the findings from the physical examination, medical history, and laboratory tests, healthcare professionals can accurately diagnose diphtheria and initiate appropriate treatment promptly.

Diphtheria treatment requires prompt action to neutralize the toxin and eliminate the bacteria:

Antitoxin

Diphtheria antitoxin is a medication that neutralizes the diphtheria toxin circulating in the body. It is essential to administer the antitoxin as soon as possible to prevent further damage to the heart and nerves.

Antibiotics

Antibiotics, such as penicillin or erythromycin, are used to kill the Corynebacterium diphtheriae bacteria. This helps to stop the spread of infection and prevent complications.

Supportive care

Depending on the severity of the illness, supportive care may include: 

• Hospitalization: Patients with moderate to severe diphtheria often require hospitalization for close monitoring and treatment.
• Bed rest: Rest is important to allow the body to recover.
• Oxygen therapy: If breathing is difficult, oxygen therapy may be necessary.
• Fluids: Intravenous fluids may be given to prevent dehydration.
• Airway management: In severe cases, a breathing tube may be needed to keep the airway open.

Factors that increase the risk of diphtheria include:

• Lack of vaccination: People who are not vaccinated against diphtheria are at the highest risk. This includes individuals who have not received the primary series of vaccinations in childhood or who have not had their booster shots.
• Living in crowded or unsanitary conditions: These conditions increase the risk of exposure to the bacteria. Overcrowding and poor sanitation can facilitate the spread of respiratory infections.
• Weakened immune system: People with weakened immune systems, such as those with HIV/AIDS or cancer, are more susceptible to1 infections, including diphtheria.
• Travelling to areas where diphtheria is common: Travellers to certain regions, particularly countries with low vaccination rates, may be at increased risk of contracting diphtheria.

Diphtheria can lead to serious complications, such as:

• Breathing problems: The membrane in the throat can obstruct the airway, leading to difficulty breathing and potentially respiratory failure.
• Heart damage: The diphtheria toxin can damage the heart muscle, causing myocarditis (inflammation of the heart muscle). This can lead to heart failure and other life-threatening complications.
• Nerve damage: The toxin can also damage nerves, leading to paralysis, numbness, or difficulty speaking or swallowing.
• Kidney failure: In severe cases, diphtheria can lead to kidney failure.
• Death: Diphtheria can be fatal, especially if left untreated.

If you or someone you know has diphtheria, it is important to:

• Follow the doctor's instructions carefully. Take all medications as prescribed and complete the full course of antibiotics, even if you start to feel better.
• Get plenty of rest. Rest is crucial for recovery. Avoid strenuous activity and allow your body to heal.
• Stay hydrated by drinking plenty of fluids to prevent dehydration.
• Isolate yourself from others to prevent the spread of infection. Stay home and avoid contact with others until your doctor says it is safe. This usually involves staying home for at least 48 hours after starting antibiotic treatment.

Diphtheria is only a childhood disease.

While diphtheria is more common in children, adults can also get infected, especially if they are not vaccinated or their immunity has waned.

Diphtheria is not serious.

Diphtheria is a potentially life-threatening infection that can lead to serious complications, including heart damage, nerve damage, and even death.

Vaccination is not necessary.

Vaccination is the most effective way to prevent diphtheria. Widespread vaccination has dramatically reduced the incidence of diphtheria, but it is still important to stay up-to-date on vaccinations to protect yourself and others.

Seek immediate medical attention if you or your child experiences:

• Thick, grey membrane at the back of the throat
• Difficulty breathing or swallowing
• High fever
• Severe sore throat
• Unexplained weakness or fatigue
• Skin sores that are slow to heal

If you are diagnosed with diphtheria, consider asking your doctor the following questions:

• What is the best course of treatment for me?
• How long will it take me to recover?
• What are the potential complications of diphtheria?
• When will I be contagious?
• How can I prevent spreading diphtheria to others?
• Will I need any follow-up tests or treatment?

If someone you know has diphtheria, you can support them by:

• Offering practical help: Help with errands, childcare, or meal preparation.
• Providing emotional support: Offer encouragement and reassurance.
• Educating yourself about diphtheria: Learn about the infection and how to prevent its spread.
• Respecting their need for isolation: Understand that they need to isolate themselves to prevent spreading the infection.
• Checking in on them regularly: Stay in touch by phone, text, or video call to see how they are doing and offer support.

Diphtheria is a serious but preventable disease. Diphtheria immunisation is the most effective way to protect yourself and your loved ones. If you suspect you or someone you know has diphtheria, seek immediate medical attention.