Diphtheria | خناق

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Blood agar culture with Corynebacterium diphtheriae colonies – source US CDC
Blood agar culture with Corynebacterium diphtheriae colonies – source US CDC

Diphtheria is an infectious disease caused by bacteria.

Diphtheria is a serious infection; and can result in severe damage or death if proper treatment is not initiated immediately.

Typically it affects throat and nose; causing sore throat and high fever. Diphtheria rarely causes skin infection.

Diphtheria is highly infectious; it can transmit from an infected person to the other when they are in close contact. The bacteria travel through the droplets when the infected person coughs or sneezes. It can also transfer from a skin lesion (skin diphtheria).

The diphtheria bacterium produces a toxin (poison) in the throat or nose, which damages the cells and tissues of the throat. The dead tissues of the throat make a membrane (referred as pseudo membrane), which gets in the way of air passage resulting in obstructing or blocking breathing.

The toxin may also severely damage the heart, kidneys and nerves when absorbed in the blood stream.

The diagnosis is usually made on clinical signs and symptoms. Lab tests are also required, but if diphtheria is suspected, in most occasions it is recommended to start the treatment immediately and not to wait for the lab results.

Diphtheria used to be very common in worldwide. The number of cases of diphtheria has dropped significantly after the implementation of childhood vaccination. However, in Pakistan there are still a few thousand cases occur every year. Majority of the cases can be easily avoided if all children receive the vaccine in their childhood.

Diphtheria cases are extremely rare in Europe and USA due to proper implementation of vaccination program. Diphtheria vaccination must be given to children as part of the childhood vaccination program. (see vaccination schedule)

The symptoms of diphtheria start to appear after 2 – 5 days of exposure to diphtheria bacteria. The time period required to establish any infection in the body is called incubation period.

The symptoms of diphtheria include:

 High fever, usually above 100.4 F

 Sore Throat and hoarse voice

 Cough and breathing difficulty

 Feeling cold

 Weakness (feeling very tired)

 Pain in swallowing

 Headache

 Bad smelling discharge from nose

 Inflammation or swollen gland in the neck

The patient feels a membrane in the back of the throat obstructing breathing and swallowing. The membrane bleeds if try to remove physically.

Some people suffer a mild form of diphtheria in which they do not experience any or most of the above symptoms. However, they can still spread the infection to others. They are considered as carrier.

Cutaneous Diphtheria (infection of skin)

Diphtheria can infect the skin, it is however very uncommon. It usually occurs when the personal hygiene standards are not adequately maintained. The patient develops blisters containing the pus in the legs, feet and arms. These blisters can become large ulcers and transform into sore-looking skin. These sores take long time to heal (usually 2-3 months).

Diphtheria is caused by bacteria. Usually two types of bacteria can cause diphtheria:

1 Corynebacterium diphtheriae

2 Corynebacterium ulcerans

The bacteria can spread through the droplets or salivary secretions of the infected person to the uninfected person when in close contact.  When the infected person sneezes or coughs, small droplets of secretions spread containing the bacteria. These small droplets are hard to see in air. It can also transmit from items used by infected person like towels, utensil or toys.

Once the bacteria enter the body, it starts to multiply itself on the inner surface of throat or nose. The bacteria produce toxin (poison) which starts to kill the inner surface tissues of the throat and nose. The dead tissues/cells of the throat make a membrane (referred as pseudomembrane) which blocks the breathing passage causing suffocation.

Diphtheria can rarely cause skin infection. It usually occurs when personal hygiene standards are not maintained. In case of skin infection, bacteria can spread from the infected wound to the other person.

The toxin may also damage heart, kidneys and nerves when absorbed in the blood stream.

Doctor may suspect diphtheria, if the patient is complaining of sore throat and difficulty in swallowing with a gray membrane developed in the throat covering the tonsils.  The doctor or lab technician may take a sample from the membrane using a throat swab.  A positive throat swab test will confirm the diagnosis of diphtheria.

In diphtheria infection on the skin, swab sample should be collected and send to the lab asap for laboratory testing.

Based on clinical signs and symptoms, if diphtheria is suspected, it is recommended to initiate the treatment immediately and do not wait for lab confirmation.

Since diphtheria is a serious condition, treatment is initiated immediately.

In case diphtheria is suspected, it is appropriate to admit the patient in the hospital and keep him isolated from other patients to prevent spreading of the infection to the other patients or health care workers.

If the membrane inside the throat is making it difficult to breath, a part or the whole membrane is required to be removed by minor surgical procedure.

There are two main types of drugs used to treat the infection:

Antitoxin treatment

Patient should be given antitoxin specific for diphtheria toxin. Antitoxins are drugs that neutralize the toxin. Antitoxins are specific antibodies against specific type of toxin; for example diphtheria antitoxin would only be effective against diphtheria toxin; same as tetanus antitoxin would only be effective against tetanus toxin.

Before giving the antitoxin, it is suggested to carryout the skin allergy test to make sure that the patient is not allergic to the ingredients of antitoxin product.

Antibiotic Treatment

Antibiotic therapy is also required to treat diphtheria infection.  In the beginning 14 day antibiotic therapy is required, which may be extended if bacteria is still detected in laboratory testing.

Diphtheria infection used to be very common worldwide.   The number of diphtheria cases have significantly dropped globally due to increase use of diphtheria vaccine.  

There are still a few thousand diphtheria cases occur every year in Pakistan.  Majority of the cases can be easily avoided by increasing diphtheria vaccination coverage.

Diphtheria vaccination must be given to children as part of the childhood vaccination program (see Vaccination Schedule)

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