Generality
Diphtheria is a severe and extremely contagious infectious disease caused by the Corynebacterium diphtheriae bacillus.
The diagnosis of diphtheria is almost always based on simple physical examination and medical history.
To be implemented in the hospital, the standard treatment involves the administration of the so-called diphtheria antitoxin, associated with an ad hoc antibiotic treatment.
Today, thanks to the advent of the vaccine and cutting-edge vaccination programs, diphtheria is much less widespread than it used to be; the only geographical areas where it still represents a danger are the underdeveloped countries, in which hygiene leaves much to be desired and medical care is scarce.
What is diphtheria?
Diphtheria is an infectious disease of bacterial origin, extremely contagious, which causes a characteristic acute inflammation of the mucous membranes of the nose, throat (or pharynx), larynx and sometimes even trachea.
To make diphtheria unique in its kind is the formation - at the level of the throat - of a gray-black and thick mass, which tends to impede the passage of air, thus compromising breathing (the more the mass positions itself towards the trachea, the greater the probability that breathing difficulties will arise).
Diphtheria as a respiratory disease
In light of the impediment to respiration to which it may give rise, diphtheria is included in the list of respiratory diseases affecting the upper airways (ie nose, pharynx, larynx and trachea), as well as in the list of bacterial infectious diseases. .
An exception to the rule: cutaneous diphtheria
As described above, diphtheria typically affects the upper airways. However, in the presence of certain circumstances (in this case in geographical areas with tropical climate and where hygiene is poor) it can affect the skin.
Diphtheria that causes damage to the skin is called cutaneous diphtheria .
Epidemiology
Today, diphtheria is an uncommon infectious disease, especially in industrialized countries, but once, before the advent of anti-diphtheria vaccine, it was a widespread infection and was one of the main causes of death among children.
The most recent epidemiological estimates, related to diphtheria, say that:
- In 2015, 4, 500 cases of diphtheria were recorded worldwide, against the 100, 000 reported 25 years earlier, in 1980;
- Also in 2015, the deaths of diphtheria were 2, 100, against 8, 000 in 1990;
- Current diphtheria mortality is 5-10% of clinical cases;
- The countries of the world with the least clinical cases are the most developed, such as the United States (only 57 cases between 1980 and 2004) or the United Kingdom (only 20 cases from 2010 to 2015). On the contrary, the most affected countries of the world are those in development and where sanitation standards are poor, such as sub-Saharan African states, India, Indonesia etc .;
- In Italy, between 2015 and 2016, 8 cases were registered.
Causes
As stated initially, diphtheria has a bacterial origin, ie it is the result of the action of a bacterium. To be precise, the bacterium that causes diphtheria is the so-called Corynebacterium diphtheriae .
Corynebacterium diphtheriae : some details
Discovered by Edwin Klebs in 1883, Corynebacterium diphtheriae is a Gram positive bacterium, which, according to the most recent descriptions, includes 4 different biotypes : the Gravis biotype, the Mitis biotype, the Intermedius biotype and the Belfanti biotype.
Except for the Belfanti biotype, all the other biotypes of Corynebacterium diphtheriae produce a toxin, namely an exotoxin, very simply called diphtheria toxin (it is a peptide).
Corynebacterium diphtheriae is a microorganism with a tendency to localize near or close to the mucous membranes of the pharynx and the very first respiratory tract, and here it reproduces, also giving rise to the formation of the aforementioned exotoxin.
Curiosity: what distinguishes the various biotypes of Corynebacterium diphtheriae ?
Without going into too much detail, the distinction in biotypes of Corynebacterium diphtheriae is based on some morphological and biochemical characteristics of the bacterium in question.
Contagion - How is Corynebacterium diphtheriae transmitted?
Having the particular ability to reproduce near or close to the mucous membranes of the throat, Corynebacterium diphtheriae is a microorganism whose transmission, between humans, can take place through:
- Inhalation of droplets of infected saliva, ie containing the pathogen.
To emit these droplets is, clearly, an individual bearer of the infectious disease in question, when he coughs, sneezes or simply speaks; inhalation, on the other hand, obviously concerns a future new guest.
The transmission route described above, which assigns the role of disease vehicles to saliva droplets emitted by the sick, is called via aerosol .
The infectious diseases transmissible by aerosol make the overcrowded places ideal environments to contract the triggering pathogen.
- The manipulation of objects previously used by infected people, thus contaminated by the causal agent. Among the contaminable objects that most commonly a disease such as diphtheria can spread, there are towels, bed sheets, door handles and sanitary taps.
It should be noted that the transmission of diphtheria through the manipulation of contaminated objects is possible but infrequent.
- Contact with a skin lesion present on an infected individual. It is a mode of transmission of real diphtheria, but definitely not very common, perhaps even less than the previous one.
Risk factors
Since the diphtheria vaccine has existed, the main risk factors for diphtheria are:
- Failure to obtain vaccination. In developing countries, vaccination is not yet a well-planned practice.
Among the unvaccinated subjects, those most at risk of getting diphtheria are children under the age of 5 and the elderly, as the immune system of these individuals is, for different reasons, not very efficient;
- The presence of diseases that compromise the function of the immune system, such as AIDS;
- The poor sanitation measures, typical of underdeveloped countries of the world.
Symptoms and complications
To learn more: Diphtheria Symptoms
As mentioned at the beginning of the article, diphtheria is typically responsible for the formation of a gray-black mass on the throat, sometimes similar to a membranous patina; this mass, due to the occupied position, acts as a sort of plug which hinders the passage of air and prevents the correct performance of the respiratory acts.
A distinctive clinical sign of diphtheria, this gray-black mass has a semi-solid consistency and is the result of the combined effects of bacterial multiplication, exotoxin production, necrosis of the underlying mucous tissue and the host's immune response.
But diphtheria is not only this, but it is also the cause of a wide spectrum of symptoms and other signs, such as:
- Temperature;
- Enlarged lymph nodes of the throat;
- General weakness;
- Alterations in the color scheme of the skin, which reaches a bluish color;
- Cough;
- Painful swallowing, difficulty breathing, sore throat and hoarseness.
They are all symptoms connected to the presence, in the throat, of the aforementioned gray-black infected mass;
- runny nose;
- Vision problems (rare);
- Slurred speech.
How soon do the first symptoms appear?
Generally, the first symptoms of diphtheria appear after 2-3 days from the infection of the host.
The onset of the various manifestations is gradual.
As a rule, the earliest ailments consist of sore throat and fever.
Symptoms of cutaneous diphtheria
Cutaneous diphtheria does not affect the respiratory tract, but produces ulcers - that is lesions - in some areas of the skin.
The ulcers that characterize the cutaneous diphtheria appear as excavated areas, covered with greyish patina (like the one that covers the throat in classical diphtheria) and with the margins often detected; in addition, they cause redness around the area of interest, pain and / swelling.
Special case: non-symptomatic patients
For reasons that are still unclear, a modest percentage of diphtheria sufferers do not complain of important symptoms, if not weakness and malaise. Despite the absence of symptoms, these patients are still carriers of diphtheria and are so in their own unawareness and of those who have contact with them, which complicates the implementation of the right preventive measures.
Complications of diphtheria
Diphtheria is a disease to be reckoned with; in fact, if it lacks specific care, it can degenerate into various complications, some of which are fatal.
Going into more detail, these complications include:
- Respiratory failure . It is the result of the progressive enlargement of the gray-black mass formed at the level of the throat and which constitutes an ever greater impediment to breathing.
In the more advanced stages, the respiratory insufficiency due to the obstacle present in the throat reaches such a degree as to cause the death of the patient, by suffocation.
The situation is further complicated by the possible detachment of some portions of the gray-black mass located in the throat and their transfer to the lungs; these portions contain, clearly, bacterial colonies and diphtheria toxins, therefore their passage in the lungs involves the beginning of an inflammatory process of infectious origin also at the level of the lung tissues.
- Cardiac damage . The lack of treatment of diphtheria leaves full freedom to the bacterium Corynebacterium diphtheriae to propagate, to a blood level, its own toxins. Being transported by the blood, diphtheria toxins spread into various organs of the human body, producing permanent damage.
Among the organs in which diphtheria toxin can spread, it is the heart and the complications that can give rise to it are: myocarditis (inflammation of the myocardium), congestive heart failure and sudden cardiac death. If for the last of these three complications gravity is easy to understand, for the other two it is good to specify it, remembering that they are two medical conditions capable of drastically affecting the functioning of the cardiac organ.
- Damage to the nervous system . These originate in the same way as heart complications, so they are the result of the diffusion of the diphtheria toxin into the bloodstream.
The damage to the nervous system, produced by an inadequately treated diphtheria, may consist of:
- Injuries to the nerves that reach the throat and control the mechanism of swallowing. This further affects the already present swallowing difficulties.
- Injuries to the nerves that control the respiratory muscles (ex: diaphragm). Capable of causing paralysis of the aforementioned muscles, these injuries make breathing even more difficult.
- Injuries to the nerves of the lower and upper limbs. Such neurological damage is responsible for muscle weakness.
- Injuries to the nerves that control the bladder. These injuries result in an inability to completely clear the bladder during urination.
- Kidney damage . Responsible for kidney failure, kidney damage represents a possible complication of diphtheria-supported forms of the Gravis biotype of Corynebacterium diphtheriae .
The diphtheria caused by the Gravis biotype of Corynebacterium diphtheriae is probably the most severe diphtheria form, so much so that it is also called malignant diphtheria .
When should I go to the doctor?
Diphtheria is an infectious disease subject to mandatory reporting within 12 hours of assessment. In other words, when a doctor diagnoses a case of diphtheria, he has the duty to report them to the health authorities of his country, before 12 hours have elapsed from the identification.
In light of this, it is easy to see how important it is to immediately contact a doctor or go to the nearest hospital as soon as possible, even when there is even the slightest suspicion of diphtheria.
According to experts, any contact between people who are definitely sick with diphtheria and people not yet vaccinated or who have doubts about obtaining the vaccine would justify a suspicion.
Diagnosis
To diagnose diphtheria, the analysis of symptoms and signs is often sufficient, which takes place on the occasion of the physical examination (or physical examination ) and the medical history .
As stated on more than one occasion, in fact, diphtheria is responsible for distinctive manifestations, first of all the gray-black patina located in the throat and following the enlargement of the lymph nodes, the sore throat, the inflammation of the larynx, the difficulty swallowing and breathing etc.
Which exam ascertains what was found during the physical examination and the medical history?
What is the diagnostic test that ascertains the presence of cutaneous diphtheria?
If the collection and analysis in the laboratory of a fragment of infected tissue from the throat is the practice to ascertain the presence of the most classic form of diphtheria, the collection and analysis in the laboratory of an infected tissue fragment from a skin lesion they represent the diagnostic procedure to verify the presence of cutaneous diphtheria.
Therapy
To learn more: Diphtheria medications
Diphtheria is a very serious and contagious disease, which requires immediate and particularly aggressive therapy against the responsible bacterium, as well as hospitalization and isolation of the patient in the hospital.
What is diphtheria therapy?
Starting even in cases of suspected infection, diphtheria therapy essentially involves the administration of the so-called diphtheria antitoxin intravenously or intramuscularly, followed by ad hoc antibiotic treatment usually based on erythromycin, penicillin G and procaine.
- The diphtheria antitoxin serves to neutralize the diphtheria toxin present in the bloodstream. Remember that diphtheria toxin is the main cause of the various complications that diphtheria can cause.
- The administration of antibiotics, on the other hand, is essential to kill the infecting bacterium. The use of antibiotics also serves to reduce the patient's contagiousness.
Curiosity
The pharmacological treatment for the treatment of diphtheria is very important, not only for the purpose of healing the patient from the infection, but also to avoid the spread of the same disease (which is highly contagious); in fact, several studies have shown that, even when diphtheria is asymptomatic, the infected person can spread the infectious disease in question up to 6 weeks after infection.
WHAT HAPPENS WHEN THE PATIENT IS ALLERGIC TO THE DIPHTERIC ANTITOSIN?
Since there is an allergy to diphtheria antitoxin, doctors, before administering the latter, perform a rapid skin test on patients with diphtheria, which verifies the presence of the aforementioned allergy.
If the test is positive (that is, there is an allergy), a desensitization intervention against diphtheria antitoxin is foreseen, which consists, very briefly, in the administration of increasing amounts of the aforementioned drug (NB: we start from very small doses and appropriate doses are reached after several administrations).
What does hospitalization involve?
Considering the possible cardiac and respiratory complications, the hospitalization of the patient with diphtheria involves the periodic monitoring of heart rate and respiration, and, in particularly serious cases, oxygen therapy.
Furthermore, during hospitalization, it is very common for the patient to receive intravenous fluids, in order to avoid possible states of dehydration.
Curiosity: where is the hospitalization of the patient with diphtheria held?
In case of diphtheria, hospitalization of the patient takes place in intensive care .
Intensive care is the hospital ward reserved for the hospitalization of patients in serious health conditions, who need continuous treatment, monitoring and medical support, in order to maintain their vital functions normally.
Treatment of cutaneous diphtheria
The treatment of cutaneous diphtheria involves the careful washing of wounds with soap and water, and possibly an antibiotic treatment based on erythromycin. Some time after washing - to be precise two weeks later - the patient will have to undergo a check, which assesses whether the bacterium has been completely eradicated or not.
As readers will certainly have noticed, the administration of diphtheria antitoxin is not expected; this is due to the fact that cutaneous diphtheria does not generally involve the spread of diphtheria toxin in the blood.
Prognosis
The prognosis in case of diphtheria depends on several factors, including:
- The severity of the infectious disease . There are more aggressive forms of diphtheria than others, therefore even more difficult to cure successfully. An example of very serious diphtheria is the aforementioned diphtheria produced by the Gravis biotype of Corynebacterium diphtheriae .
- Timeliness of diagnosis and treatment . The sooner the diagnosis and treatment take place, the greater the hope of recovery, without infectious disease causing permanent damage to important organs and structures such as the heart and nerves.
Remember that today, diphtheria has a mortality of 5-10% (therefore 5-10 patients die every 100).
The main cause of death is suffocation.
Prevention
The best way to prevent diphtheria is to get the vaccine at a young age and repeat it every 10 years, according to the vaccination reports.
The most recommended vaccines are Infanrix hexa and Infanrix penta, indicated both for the prevention of diphtheria and for tetanus, pertussis, poliomyelitis and Haemophilus influenzae B infections.
