Diphtheria – Causes, Symptoms, Diagnosis and Treatment

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Diphtheria is of world wide distribution being commonest in temperate climates. It is highly contagious disease and infection spreads mainly through droplet infection by speaking, coughing or sneezing. The organisms reside in secretions from the nose and throat, in membrane formed in throat, infected wounds and spread occasionally through close contact.

The causative organism is corynebacterium diphtheria, a gram positive, non sporing organism which is slender rod like, straight or slightly curved with a tendency to branch. Based on biochemical reactions and haemolytic properties C diphtheriae has been divided into three main type’s gravis, mitis and intermedius type. All these three strains produce a potent toxin responsible for its virulent effects.

The incubation period is usually two to six days and spread of infection is through close contact. Children are the most prone to suffer from it though occasionally it may involve adults. Untreated patients are usually infective upto a period of two weeks.

Cutaneous diphtheria, called the C diphtheria organism when it gains entry through abrasions and wounds produces punched out ulcers often covered by greyish membrane.

Conjunctival diphtheria. It is due to direct involvement of the eyes by the organism or may spread from nose. It generally occurs in very small children and is characterized by severe congestion in eyes and a discharge.


They can be:

1. Acute circulatory failure. It may develop in the first few days.

Toxic myocarditis in a case of diphtheria is a serious complication. It is characterised by tachycardia, feeble heart sounds, cardiac enlargement, tic tac rhythm and arrhythmias. Sudden death may occur.

Congestive heart failure is not very common. Electrocardiographic changes are generally non-specific.

2. Respiratory complications like bronchitis, bronchopneumonia, respiratory obstruction and respiratory paralysis may occur in it.

3. Toxic neurological damage generally occurs in 3rd to 6th week. It may be paralysis of palate and of accommodation, facial  and bulbar paralysis and muscles of respiration. Peripheral neuropathy also develops though at a late stage.

4. Renal complications like toxic nephritis. It is generally seen on 10th day.

5. Vascular involvement especially of middle cerebral artery leading to a picture of thrombosis or monoplegia.

6. Other complications include otitis media and arthritis.


In addition to clinical picture of a sore throat toxaemia and a greyish membrane adherent to the pharynx diagnosis is confirmed by direct smear and culture of secretions either by a nasopharyngeal or laryngeal swab and demonstrating the organism.

Schick test is done to determine whether an individual is susceptible to diphtheria or not. Intracutaneous injection of 1/50 MLD of toxin contained in 0.1 cc of diluent is injected. Susceptible person shall show a reddish reaction in 24-36 hours. Late positive reaction may be observed after one week.


General supportive measures like soft semisolid food analgesics and antipyretics.

Specific therapy consists in the administration of anti-diphtheria serum (ADS) in the dose ranging from 20,000 units to 120,000 units depending on the extent of involvement and severity of disease process. Drug is to be given by intramuscular route. Before giving ADS sensitivity test be done.

Since C. diphtheriae is sensitive to erythromycin and penicillin these drugs are given as adjuvant to antitoxin. Injection Penicillin 5 lacs unit I/M or Erythromycin 40 mg/kg body weight in four divided doses for seven days. These drugs are sufficient to take care of the disease as well as secondary infection.


Cardiovascular complications are the major risk. In addition to antitoxin, antibiotics vasopressor drugs in circulatory collapse. Injection Betamethasone 8 mg four times a day is beneficial. Cases who develop arrhythmias shall require appropriate drugs. Digitalis is indicated if congestive failure develop.

In cases where there is palatal paralysis in acute stage nasogastric tube feeding may be required. Respiratory paralysis is managed by oxygen and ventilator.


For passive immunization 1000- 2000 units of diphtheria antitoxin for temporary protection to all close contacts are given. Immunity lasts for two weeks. In addition all close contacts be given erythromycin (40 mg/kg/day for seven days) as anti-microbial prophylaxis.

Active immunization of all children with triple vaccine containing diphtheria. Tetanus and pertussis (DPT) is done at third month followed by further two docs at monthly interval.


It depends on the severity of disease process as well as on the type. It is poor in severe and malignant form, Very small children carry poor prognosis.

Haemorrhagic symptoms, cardiovascular collapse and respiratory paralysis carry poor prognosis.

Clinical picture

It may have a mild, moderate or severe course. The clinical picture of any case shall depend on the site which is involved.

All cases have prodromal symptoms in the form of headache, sore throat, malaise, nasal discharge, vague aches and pains in the body and loss of appetite. Fever is moderate in intensity but may come on with chills.


The various forms are:

1. Pharyngeal

2. Laryngeal

3. Nasal

4. Cutaneous

5. Conjunctival

Pharyngeal diphtheria

It is the commonest form and is characterised by toxemia, congestion and edema of palate with formation of a membrane in pharynx which is generally thin glistening pearly white in early stages and becomes thick, greyish and opaque later on. It is adherent to underlying structure and has well defined borders. It bleeds on forcible removal. It may extend to palate, uvula.

There are feature of lymphadenopathy in neck (bull neck appearances), breath foul smells. Fever does not correspond to the gravity of the disease.

In second week patient may pass into circulatory collapse. There is lethargy and restlessness. ‘Pulse may become irregular. Respiration is rapid and shallow. Repeated vomiting takes place. Some patients may pass into cardiac failure. Neurological complications occur in the third week. It may be in the form of paralysis of palate and pharynx.

Laryngeal diphtheria

It is common in young children and is characterized by hoarseness, brassy cough followed by attacks of inspiratory stridor, and laryngeal spasm. Membrane is generally limited to larynx and may spread to air passages. These children suffer from respiratory obstruction and may run a fatal course.

Nasal diphtheria

It is in the form of a serous discharge followed by a mucopurulent one often blood stained. Here the membrane is confined to the anterior part of nasal septum. The disease is often unilateral. There is foul smell coming. It may be the only way of presentation. It may extend to other parts of pharynx. This is not very common and is present in only two to three per cent of cases.

Quick Summary

1. Incubation period-2-6 days

2. Etiologic agept- Corynebacterium diphtheriae

3. Varieties of diphtheria-Pharyngeal, laryngeal, nasal, cutaneous, conjunctival

4. Complications of diphtheria-Toxic myocarditis, acute circulatory failure Bronchitis, bronchopneumonia, otitis media,Paralysis of palate, bulbar and facial, cerebral thrombosis Toxic nephritis schizophrenia. Typhoid meningitis may be seen in an occasional case especially in children.



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