Diphtheria

It is called diphtheria infection of mucous membranes or skin caused by a bacterium called Corynebacterium diphtheriae.

There are two types of diphtheria:

• The cutaneous (mainly affects the skin).
• Respiratory (affects the respiratory tract and is usually much more dangerous than skin).

One of the factors that determines the appearance in a certain area of ​​one type or another of diphtheria is the climate.

In populations of temperate climates, diphtheria with respiratory involvement usually occurs. Although it occurs throughout the year, it has a higher incidence in the cold months. In tropical regions, on the other hand, skin is more frequent. It also occurs throughout the year and is often seen as a secondary infection complicating other dermatitis.

Why does diphtheria occur?

The infection is caused by an aerobic bacteria called Corynebacterium diphteriae. A characteristic of this bacterium is the ability to synthesize a substance called a toxin. This toxin is a protein that, as its name suggests, can cause toxicity in the body. The strains that produce toxin tend to be mainly those that affect the respiratory system.

Man is the reservoir for the bacteria, and contagion is normally produced by close contact with the patient or the carrier of the disease, although it seems that the risk of contagion is greater when the contact is with a sick person.

In most cases, the bacteria pass to the healthy individual through the airway. Another possibility of contagion is coming into contact with fomites, since the bacteria can survive in the environment for weeks or months.

The incubation period for the disease is between 2 and 5 days. It can be prolonged on some occasions, but very rarely it exceeds 8 days. The bacterium infects the mucous membranes, especially those of the respiratory system, and invades open skin lesions (wounds, insect bites).

In the event that the bacteria have the capacity to produce the toxin, hyperemia and edema usually occur, which can later cause necrosis of the epithelium and acute inflammation. The coagulation of the cellular debris and the pus gives rise to a pseudomembrane, and the inflammatory reaction spreads to the tissues near the infected one. The toxin acts locally or generally.

Once absorbed it can cause myocarditis, polyneuritis and necrosis of other organs such as the kidneys, liver and adrenal glands.

Diphtheria symptoms

Two types of patients must be distinguished:

• Asymptomatic carriers
• Sick

Symptoms and signs vary according to the affected place and the intensity of the affectation. Other factors that determine the severity of the disease are age and the presence of respiratory pathologies simultaneous to the infection. Nausea and vomiting usually occur in children, while in adults a sore throat is characteristic. Low-grade fever and dysphagia appear in half of the patients, although cough, hoarseness, chills and rhinorrhea may also appear. In severe infections, apathy, paleness, and tachycardia appear.

A small percentage of patients may present with an abrupt onset of malignant diphtheria, formation of pseudomembranes in the respiratory system, stench of breath, swollen tonsils, muffled voice, cervical lymphadenopathy, submandibular edema, and severe toxicity. The normal thing in our environment is that it is diagnosed in time and treated. The location of the affectation can be of several types:

• If the involvement is Tonsil, increasingly dense pseudomembranes form and adhere to the pharyngeal tissue with great intensity, of a grayish color. They have a special characteristic and that is that when you try to remove the membrane to evaluate the exudate, a small hemorrhage can be caused.
• If the involvement is NASAL, the patient usually presents a bloody rhinorrhea that irritates the nostrils or the lip.
• CUTANEOUS diphtheria is usually an infection secondary to pre-existing dermatitis in the infected patient. The affectation will be more or less frequently in the lower and upper limbs, head and trunk.

Complications

The most serious are due to obstruction of the airways due to the pseudomembranes that cover the airway. The risk of respiratory obstruction is more important if the infection affects the larynx and the tracheobronchial tree, and is higher in children because their airways are smaller.

Myocarditis can appear during the acute phase, develop as the local process improves, or begin several weeks later. Therefore, it is always necessary to monitor the state of the patient’s heart by means of an ECG.

Manifestations begin in the first 2 weeks with pharyngeal and palate paralysis, resulting in nasal voice, dysphagia, and refluence of ingested fluids into the nose. Peripheral polyneuritis occurs at approximately 1-3 months and consists of a weakness of the limbs of the body. Paresthesias may appear in the hands and feet. In severe cases of diphtheria, total paralysis with respiratory failure can occur. Other complications that can occur in diphtheria are: pneumonia, kidney failure, encephalitis , stroke, pulmonary embolism or endocarditis .

How is it diagnosed?

We can think of it when pharyngeal pain, lymphadenopathy or cervical swelling and low-grade fever appear, especially if it is accompanied by symptoms of toxic infection (hoarseness, stridor, palate paralysis or bloody discharge).

In the patient, a dense, grayish pseudomembrane may or may not be found on the palate, nasopharynx, nostrils, or larynx.

Confirmation of the diagnosis is made by isolating Corynebacterium diphteriae in samples from local lesions of the patient, using the PCR technique.

In patients with cutaneous diphtheria, tests should be performed on skin samples and respiratory involvement should be ruled out by analyzing pharyngeal samples.

Diphtheria treatment

Treatment should begin at the time of suspicion of the disease, even if it has not been confirmed by laboratory tests, since each day of delay poses a risk to the life of the patient.

It is performed with diphtheria antitoxin, obtained from horse serum. Previously, it should be investigated that the patient has no allergy to this serum by means of a conjunctival or intradermal test (detection of local allergic reaction).

Antibiotics can sometimes be used to treat local lesions. The most used are Macrolides and Penicillins.

How can I avoid it?

Currently there is a vaccine for the prevention of the disease that is included in the official Spanish vaccination calendar. The calendar is shown in table I:

* DTP: diphtheria, tetanus and pertussis vaccine.
** DT: vaccine against tetanus and diphtheria in children.
*** TD: Tetanus and Diphtheria Vaccine in Adults.

It is advisable to repeat the dose every 10 years for both diphtheria and tetanus, preferably in the middle of each decade (15, 25, 35 … years). Patients who have suffered the disease should be vaccinated after their recovery.

Due to the fact that vaccination against diphtheria has been systematic in the population for years, the presence of the disease in our country is difficult.

However, people who have been in close contact with diphtheria patients should be kept under surveillance for at least 1 week to rule out the disease.

If the cultures are positive, they should be treated with the antibiotics listed above, and receive a booster dose if it has been more than 5 years since they received the vaccine.

Normally the presence of respiratory symptoms in our country is due to other diseases ( flu , colds, pneumonia) and if you present these symptoms you should not be alarmed. However, if you have been in contact with someone who has the disease, you should see a doctor to rule out a possible contagion.

In principle, this situation is rare due to the comments previously made about vaccinations in our country.