Diphtheria is an infectious disease caused by bacteria Corynebacterium diphtheriae. The infection affects the respiratory passage leading to sore throat and breathing difficulties. The disease produces a thick membrane in the back of the throat that can occlude the airway passage putting patients life in danger from respiratory arrest. The thick membrane is  the hallmark of diphtheria infection. The bacteria also produces toxins that may affect heart, nerves and kidneys.

Diphtheria is rare in developed countries but still common in developing countries, although number of cases has declined significantly as a result of childhood vaccination. It can be deadly in children younger than 15 years. Up to 3-10% of people who get diphtheria die from it.

Diphtheria spreads from a person to person through inhalation of  droplets released during coughing and sneezing by an infected person. The duration between exposure and occurrence of symptoms is 2 to 5 days. An infected person can transmit the infection to others for up to six weeks after the initial infection. Very rarely, diphtheria is also spread through handling of infected persons belongings that are infected with the bacteria.

Risk factors

Certain factors increase the chance of getting the infection:

• People with poor hygiene and living  in poor sanitary conditions.
• Lack of up-to-date vaccination in children and adults (lack of booster).
• Travelling to endemic areas.

Symptoms

Not everyone exposed to disease experiences symptoms although they can still spread the disease to others. The early symptoms may be similar to common cold, such as sore throat. Once the infection is established, patient will develop fever, swollen lymph nodes in the neck and experience difficulty breathing and swallowing. On examination, a thick covering of secretion called pseudomembrane is seen in the nose, throat and airways. It bleeds on scraping. If pseudomembrane formation is extensive, patient can suffocate and die from respiratory arrest.  The bacteria also produces toxins that is absorbed in the blood and affects heart, potentially causing a heart failure and death. Toxins can also cause paralysis and kidney failure.  

When to seek medical care

Diphtheria can be a serious disease. Seek medical care when:

• Difficulty swallowing or breathing.
• Chest pain, palpitation.
• Neck swelling.
• Bloody nasal discharge (sign of nasal diphtheria).
• Weakness/paralysis.
• Known underlying weakness of immune system.
• Exposure to a known Diphtheria patient.

Diagnosis

If you feel you have any signs that suggest diphtheria, you should immediately consult a doctor. Your doctor will review your  history and conduct a physical examination. The presence of gray coating on the throat or nostrils strongly suggests diphtheria. Diagnostic tests are performed to confirm diagnosis. These tests include:

• Culture of sample from throat and skin lesion:  to look for the bacteria that causes diphtheria.
• Toxigenicity test:  to help differentiate toxin producing bacteria from one that is non toxin producing.
• Other tests: Blood tests may show increased white blood cells and urine may show protein.

Treatment

Once diphtheria is suspected based on clinical finding, appropriate samples are collected and treatment started immediately. Infected person is kept in isolation until considered noninfectious. Treatment consists of:

• Antitoxin: Antitoxin binds and  neutralizes the effects of toxin produced by the bacteria.
• Antibiotics: Antibiotics like erythromycin, penicillin are used  to kill the bacteria, so that no more toxin is produced and disease spread is prevented.
• Supportive care:  Monitoring for airway, nervous system  and heart function, and treatment if any complications develop.
• Close contact of a diphtheria case should be identified and considered for antibiotic prophylaxis.

Prevention

Diphtheria can be prevented with vaccines given per national guidelines. Some governments and health systems may provide a pentavalent vaccine that include DPT (diphtheria, pertussis, tetanus) vaccine along with Hepatitis B and Haemophilus influenzae Type B vaccines. The vaccine should be administered at 6th, 10th and 14th weeks of birth and booster dose of DPT at 18th month. Your child will need to be vaccinated again around age 12 years. For adults, it is recommended that you get a combined diphtheria and tetanus (Td) booster dose.

If you are a migrant, a traveler or a laboratory and health care worker, then you need to be fully immunized with a booster dose.