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Diphtheria - Causes, Symptoms, and Treatment

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Diphtheria is a harmful bacterial infection that usually affects the mucous membranes of the nose and pharynx (nose and throat).

Written by

Dr. Geethika. B

Medically reviewed by

Dr. Pandian. P

Published At June 9, 2022
Reviewed AtMarch 10, 2023

An Overview of Diphtheria:

  • A predominant bacterial infection causes it in underdeveloped countries due to limited healthcare and vaccination options.

  • Notable symptoms include sore throat, malaise (tiredness), fever, swollen lymph nodes, and a gray, thick pseudomembrane formation in the throat.

  • The sore throat and pseudomembrane, along with the results of a bacterial culture, play a significant role in the diagnosis.

  • Vaccination plays a vital role in the prevention of this infection.

  • The infection is often eliminated by administering antibiotics and, in worst-case scenarios, hospitalizing the patients.

What Is Diphtheria?

Diphtheria is a contagious, sometimes fatal infection of the nose, throat, caused by Corynebacterium diphtheriae. These bacteria release a potent toxin (poison) that causes damage to the kidneys, heart, and nervous system. In advanced stages, it leads to difficulty in breathing, heart failure, and paralysis. It might sometimes lead to death despite treatment, especially in unvaccinated children. Centers for Disease Control and Prevention (CDC) recommends vaccines for infants, toddlers, teens, and adults to prevent diphtheria and its serious complications.

What Causes Diphtheria?

The bacteria usually multiply on the surface of the mucous membranes of the mouth, nose, or throat and cause inflammation of the tissues. The infection usually spreads through airborne droplets (when an infected person sneezes or coughs, a mist of contaminated droplets is released, which may be inhaled by the people nearby, and infect them). Handling an infected person’scontaminated belongings (such as tissues, towels,etc) can also transfer diphtheria causing bacteria to uninfected individuals.

Who Is More Prone to Diphtheria?

People who are at increased risk of catching diphtheria include:

  • Children and adults who are not vaccinated.

  • People who live in unhygienic or crowded conditions.

  • People who travel to underdeveloped tropical countries where the prevalence of diphtheria is common.

What Are the Symptoms of Diphtheria?

The patients usually develop the symptoms a few days (an average of five days) after exposure to the bacteria. Symptoms of diphtheria include:

  • Sore throat.

  • Painful swallowing.

  • Hoarseness.

  • A general feeling of illness (malaise).

  • Fever ranging between 100.4 to 102° F or 38 to 38.9° C.

  • Children may also have an increased heart rate, chills, nausea, vomiting, and a headache.

  • Swelling of the lymph nodes in the neck (called bull neck).

  • The formation of a tough, gray layer of pseudomembrane near the tonsils and the throat by the bacteria, dead white blood cells, and other substances causes the narrowing of the airway and possible paralysis of the roof of the mouth. This causes difficulty in breathing among infected patients.

  • An effect on the nerves, especially those supplying the muscles of the face, throat, arms, and legs, is produced by the toxin causing symptoms such as difficulty swallowing or moving the eyes, arms, or legs.

Some people with the infection show no apparent signs and are known to carry the bacteria in a carrier state by exhibiting only a mild illness. They are often unaware of the disease and are called carriers because they tend to spread the infection to others unknowingly.

A milder version of diphtheria affects only the skin and is more common in adults, leading to pain, erythema, inflammation, and sores or ulcers that are similar to other infections of the skin. A gray membrane covers these ulcers, and a few people have open sores that do not heal. It tends to spread by coming into contact with contaminated skin sores. This form is more common among people living in countries with poor hygiene habits.

What Are the Complications Associated With Diphtheria?

If the patient is unvaccinated or if the patient is not treated timely, it may lead to the following complications.

  • Respiratory Problems: The toxin produced by diphtheria damages the tissues adjacent to the infection — usually in the nose and throat area and leads to the formation of a pseudomembrane. The pseudomembrane may cause people to make an unusual sound while inhaling and sometimes may extend into the airway, become detached and block the airway completely. The diaphragm (an important muscle used for inhaling) may become paralyzed due to the effect of the toxin on the associated nerves, sometimes leading to respiratory failure.

  • Heart Damage: Other tissues of the body are damaged as the diphtheria toxin may spread through the bloodstream. When it damages the muscles of the heart, it causes complications such as inflammation of the heart muscle (myocarditis). The extent of damage from myocarditis can range from mild to severe. The effect of the toxin of the nerves related to the heart results in rapid heart rate, an abnormal heart rhythm, and low blood pressure. The impact on the muscles and nerves of the heart together may lead to abnormal heart rhythms, heart failure, and death.

  • Nerve Damage: The toxins affect the nerves adversely. Typically they target the nerves that supply the throat and may cause difficulty swallowing. Inflammation of the nerves that supply the arms and legs also may cause muscle weakness.

  • In case of severe infection, the toxins can also damage the kidneys.

With treatment, the majority of the patients survive these complications, but recovery is often slow. The fatality rate of diphtheria is about 5% to 10% of the time, primarily affecting children under age five or adults older than age 40.

Is There a Vaccine for Diphtheria?

Yes, with the advent of vaccines, diphtheria is not only treatable but also preventable.

The vaccine for diphtheria is usually combined with vaccines for tetanus and pertussis and is known as diphtheria, tetanus, and pertussis vaccine. The recent version of this vaccine is the DTaP(diphtheria, tetanus, and acellular pertussis) vaccine for children and the Tdap (combined tetanus, diphtheria, and acellular pertussis) vaccine for adolescents and adults. The vaccine is typically administered in the arm or thigh and is given as a series of five shots at the following ages:

  • Two months.

  • Four months.

  • Six months.

  • Fifteen to eighteen months.

  • Four to six years.

Children are advised to receive their first booster shot at around 11 or 12 years of age following these shots. The subsequent booster shots are recommended at a ten-year interval to maintain the immunity (especially when traveling to a diphtheria-prone area).

What Are the Side Effects and Complications of the Vaccine?

The common side effects experienced by children include a mild fever, irritability, drowsiness, or pain at the injection site. In rare cases, the vaccine causes an allergic reaction (hives or a rash develops within minutes of the injection) which is treatable but severe in children.

What Are the Treatment Options for Diphtheria?

  • Administering diphtheria antitoxin.

  • Antibiotics.

  • In case of respiratory symptoms, patients are usually hospitalized in intensive care units and are administered intravenous antibodies (antitoxin) to neutralize the diphtheria toxin. They are also given antibiotics, such as Penicillin or Erythromycin, for 14 days to kill the bacteria.

  • Even after completing the antibiotic course, patients are advised to isolate (to prevent other people from being exposed) until two cultures are taken to confirm that the bacteria have been killed.

  • For diphtheria of the skin, the sores are thoroughly cleaned with soap and water, and patients are given antibiotics for ten days.

  • The infection does not guarantee immunity. Hence patients are advised to get vaccinated even after recovery to prevent infection.

  • Recovery for patients with severe forms of infection is relatively slow. They are advised not to resume any physically exerting activity soon.


Diphtheria can be managed easily if the symptoms are noted early and appropriate treatment measures are provided. The best way to prevent diphtheria is by getting the vaccine at the right age intervals. Diphtheria prognosis ranges from good to poor depending on how early in the infection the patient is treated and how well the patient responds to treatment. If the patient develops sepsis or bacteremia, or if the heart is involved, the prognosis is usually bleak.

Frequently Asked Questions


What Are the Signs and Symptoms of Diphtheria?

Diphtheria symptoms include sore throat, painful swallowing, hoarseness, malaise, low-grade fever, swelling of the lymph nodes in the neck known as the bull neck, bacteria forming a tough, gray layer of pseudomembrane near the tonsils and throat, and difficulty swallowing or moving the eyes, arms, or legs.


Is Diphtheria Caused by Poor Sanitation?

If a person has poor hygiene or lives in a tropical area, they are more likely to develop cutaneous diphtheria, also known as diphtheria of the skin. Skin diphtheria typically results in ulcers and redness in the affected area. The disease is typically spread through person-to-person contact or through contact with bacteria-infected objects, such as a cup or used tissue. Diphtheria can also be contracted if one is in close proximity to an infected person who sneezes, coughs, or blows their nose.


Which Population Is at an Increased Risk of Developing Diphtheria?

Children and adults who have not been immunized, people who live in unsanitary or crowded conditions, and people who travel to underdeveloped tropical countries where diphtheria is common are all at increased risk of contracting the disease.


Is It True That Cats Cause Diphtheria?

Cats are not susceptible to developing diphtheria. However, they may act as carriers of diphtheria. One to four days after exposure to the bacteria, they may act as carriers through contamination of the rhinopharynx or fur.


How Long Does Recovery From Diphtheria Take?

Diphtheria recovery necessitates a lot of bed rest. Typically, patients recover in seven to ten days. However, there are some associated long-term complications, such as arthritis, paralysis, or brain damage.


Is Diphtheria Caused by a Virus or Bacteria?

Diphtheria is a grave infection caused by bacteria strains called Corynebacterium diphtheriae that produce a toxin (poison). It is a toxin that can make people very sick. Diphtheria bacteria spread from person to person, usually through respiratory droplets such as coughing or sneezing.


What Long-Term Effects Does Diphtheria Have on Human Beings?

Long-term effects of respiratory diphtheria (infection of parts of the body involved in breathing) may include obstruction of the airways, muscle damage in the heart (myocarditis), and damage to the nerves (polyneuropathy), the inability to move (paralysis), and failure of the kidneys.


How Long Is the Diphtheria Vaccine Effective?

According to studies, diphtheria toxoid-containing vaccines protect nearly all people (95 percent) for about ten years. Because protection diminishes with age, adults must get a Td or Tdap booster shot every ten years to remain protected.


Is It Possible to Contract Diphtheria More Than Once?

To prevent a recurrence of diphtheria, you will need to complete a full course of diphtheria vaccine after you recover. Having diphtheria, unlike some other infections, does not provide lifetime immunity. If you are not fully immunized against diphtheria, you can contract it more than once.


Why Does Diphtheria Result in Death?

Respiratory diphtheria can be fatal for some people. Even with treatment, about one out of every ten patients with respiratory diphtheria dies. Up to half of the patients may die from the disease if they do not receive treatment.


Does Diphtheria Have Any Effect on the Brain?

Diphtheria is commonly thought to be a disease of the cranial and peripheral nerves rather than the central nervous system. The central nervous system, however, is not always spared in diphtheria, despite the fact that many cases with neurologic manifestations show no anatomic changes in the brain. As a complication of diphtheria, a number of pathologic reports of cerebral hemorrhage, meningitis, ganglion cell, and nerve tract degeneration, polyradiculoneuritis of Guillain-Barré, and encephalitis have been reported.


Can Adults Contract Diphtheria?

Diphtheria is caused by a bacterial infection. It spreads quickly and easily, primarily affecting the nose and throat. It is especially dangerous for children under the age of five and adults over the age of 60.


Diphtheria Affects Which Parts of the Body?

Diphtheria can infect the respiratory tract (nose and throat mucous membranes) as well as the skin. It causes a thick, gray coating to form in the throat or nose when it enters the respiratory tract. This coating can make breathing and swallowing difficult.


Is Immunity to Diphtheria Permanent?

According to recent surveys, childhood vaccination immunity fades with age, and only 30 % of U.S. adults aged 60 to 69 years are immune to diphtheria. Because immunity to diphtheria and tetanus deteriorates over time, Td or Tdap boosters are required every ten years.


What Is the Period of Incubation for Diphtheria?

Diphtheria has an incubation period of two to five days, with a range of one to ten days. Almost any mucous membrane can be affected by the disease. Organisms can be found in discharges and lesions of untreated people two to six weeks after infection.


At What Ages Are the Diphtheria Vaccines Administered?

The DTaP (diphtheria, tetanus, and acellular pertussis) vaccine for children and the Tdap (combined tetanus, diphtheria, and acellular pertussis) vaccine for adolescents and adults are the most recent versions of this vaccine. The vaccine is typically given as a series of five shots in the arm or thigh at the following ages: two months, four months, six months, fifteen to eighteen months, and four to six years. Following these shots, children should get their first booster shot around the age of 11 or 12. The subsequent booster shots are recommended every ten years to maintain immunity (especially when traveling to a diphtheria-prone area).
Dr. Pandian. P
Dr. Pandian. P

General Surgery


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