Diphtheria

Diphtheria is a deadly bacterial infection that affects the surfaces of the nose and throat.

It is an acute toxic state rather than an infection in the conventional sense since the disease’s signs and symptoms are brought on by the toxins that the offending bacteria produce.

Despite how quickly it can spread from one person to another, diphtheria can be prevented through vaccination.

Diphtheria is typically on the list of illnesses that, if discovered, need to be reported to the appropriate national health authorities in order for them to take appropriate action and implement preventive measures.

Who, when, and where are affected by the disease?

(Epidemiology)

Although there is a worldwide occurrence of the disease, this once common epidemic disease of childhood is now well controlled in most developed countries by routine immunization of infants.

It is rare in developed countries but still found in developing countries as it is associated with the following risk factors: poverty, poor hygiene, homelessness, and overcrowding.

Since the acceptance of the expanded program of immunization by most developing countries, the incidence of diphtheria has dropped dramatically.

The peak age of occurrence is 2–14 years, especially in the unimmunized, although all ages can be affected if not immunized.

The peak incidence is in the winter or dry season.

Humans are the only known reservoirs.

What causes the disease?

(Etiology)

Infection with the bacteria Corynebacterium diphtheriae causes this disease.

Since not all of these bacteria are deadly, the virulent types produce a toxin that causes the disease’s systemic symptoms.

There are three major types of Corynebacterium diphtheriae bacteria, including gravis, intermedius, and mitis, which are linked with severe, moderately severe, and mild clinical symptoms, respectively.

Humans are the reservoir of the bacteria, and once infected, they can develop symptoms and signs, or they may not, making them carriers who can spread the infection to others.

How do people get infected?

(Transmission)

The bacteria, which is present in respiratory droplets, can be discharged through the nose and throat and spread through the air.

It can also spread by direct contact or through the exudates of skin infections.

Additionally, there have been instances of diphtheria infections caused by consuming contaminated raw milk.

From the time of infection until the onset of symptoms and signs, it typically takes 2 to 5 days, although it can take up to 17 days.

How does the disease develop?

(Pathogenesis)

Exotoxins are produced by Corynebacterium diphtheriae, and they kill bodily cells where they are secreted while also harming the tissue around them.

As a result, the symptoms and signs that are seen vary depending on the infection site and the location of toxin release.

The toxin can also be absorbed into the bloodstream, causing kidney issues, heart muscle problems (myocarditis), and general body nerve problems (peripheral neuropathy).

The tonsils, pharynx, and larynx may become acutely infected, generating a pseudomembrane or a cream-colored layer of dead tissue that is a defining feature of the disease.

Image of a child with a diphtheria thick coating in the throat
Image of a child with a thick diphtheria coating in the throat | Image source = Healthline

Laryngeal infections in children are known to cause the most severe form of the disease because of the resulting respiratory obstruction caused by exudates in the larynx and the excessive swelling in the area surrounding the throat.

This is a common cause of death from the disease, particularly in young infants with narrow airways.

Furthermore, skin infections are especially prevalent in tropical countries, where they have been shown to promote host vaccination with little morbidity.

The infection can affect any human.

However, prior natural exposure to the bacteria and vaccination may make you susceptible to the infection.

What are the indicators of infection?

(Symptoms and signs)
Diagram of the smptoms of diphtheria
Diagram of the symptoms of diphtheria | Image source = SketchBubble

The signs and symptoms of diphtheria vary depending on the area of the body that is affected.

However, the upper airway (upper respiratory tract) is the area where it occurs most frequently, particularly the tonsil and throat.

A person who is infected could experience generic, non-specific symptoms, including malaise and a low-grade fever.

Others consist of…

  1. Tonsils: swelling and pain of one or both tonsils.
  2. Throat: a painful throat that makes swallowing difficult
  3. Larynx: hoarseness of voice
  4. Nose: discharge from the nose, particularly prevalent in children under the age of one year.
  5. Ears: hearing problems and ear pain
  6. Eye: redness and discomfort in the conjunctiva of the eyes
  7. Neck lymph node: swelling of the soft tissue of the neck that causes Bull’s neck. A swollen neck might result in a respiratory obstruction, which can be fatal.

 

Pictures of cutaneous diphtheria ulcers
Pictures of cutaneous diphtheria ulcers | Image source = ScienceDirect.com

Diphtheria can manifest as a skin infection, which is more common in warm climates, and has been observed to prefer the hands and legs over the face or body.

These skin infections begin with discomfort and redness in the hands or legs affected and progress to develop shallow ulcers in the areas that are covered by membranes with well-defined margins and exudates

What are the tests done to confirm the disease?

(Investigations and tests)
  1. Culture of nose, throat, or cutaneous lesions
  2. Serum antitoxin (antibody) titer against the diphtheria toxin.

How is a diagnosis of diphtheria infection made?

(Diagnosis)

If you experience some of the aforementioned symptoms and suspect diphtheria, you must get checked out immediately at a hospital.

As you do this, keep your distance from those around you so as not to infect them if it turns out you have been infected.

Diphtheria is diagnosed clinically, which means that after examining you and determining that you exhibit the symptoms and signs listed above, your doctor can make the diagnosis.

However, a bacteriological investigation of skin lesions or swabs from the nose and mouth can help confirm the diagnosis.

What are other similar diseases that look like diphtheria?

(Differential diagnosis)
  1. Pharynx
    • Pharyngitis: pain and swelling of the pharynx
    • Peritonsillar abscess
    • Pharyngeal candidiasis (oral thrush): manifests with greyish-whitish patches in the pharynx
  2. Larynx
    • Acute Laryngotracheobronchitis ( a viral cause of infection of the upper airway)
    • Acute Epiglotittis
  3. Skin
    • Impetigo

How do you treat the disease?

(Treatment)

Immediately after making the clinical diagnosis, your doctors will administer diphtheria antitoxin, which will counteract the effects of diphtheria toxins in your body.

This is done without waiting for any tests to confirm a diphtheria infection.

Antibiotic therapy to eradicate the bacteria and halt the creation of further toxins may be administered in addition to antitoxins, for example, erythromycin or penicillin.

The clearing of airway secretions, upholding proper hygiene, and good hydration are further sorts of care that will be provided.

If you are infected, you will be kept away from other people physically until tests on fluid samples from your throat cultures reveal that there are no longer any diphtheria bacteria in your throat, which typically occurs about 48 hours after the commencement of antibiotics.

What are the unfavorable results of the disease?

(Complications)
  1. Respiratory obstruction: this is often the cause of death in infected patients.
  2. Cardiomyopathy: This occurs after about 2–10 weeks following infection; it can be fatal and manifest as unexplained heart failure.
  3. Neuropathy: This involves nerve abnormalities throughout the body.

How can we control the spread of the disease?

(Disease control)

Notify the necessary authorities to stop the spread of the diphtheria infection, as there is a very high risk of infection through contact with an infected person.

Additionally, the following precautions must be taken to protect everyone who has come into contact with the infected patient:

  1. Non-immune young children
    • Passive immunization with antitoxin serum and
    • Active immunization with toxoid (DPT Vaccine)
  2. Susceptible adult contacts
    • Active immunization with toxoid (DPT Vaccine)
    • A booster dose for already immunized persons.

A weeklong course of antibiotic prophylaxis should be given to all close contacts.

How do you prevent infection with the disease?

(Prevention)
A baby being vaccinated
A baby being vaccinated | Image source = UNICEF

Regular, active immunization of the susceptible population is the main strategy for the control of this disease.

Diphtheria toxoid vaccination has proven to be an effective strategy for containing this infection.

It is typically given between the ages of 2 and 3 months, along with the pertussis vaccination and the tetanus toxoid (DPT) vaccine.

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