July 13, 2024

Alexander Okere

A senior registrar in the Department of Oral Pathology and Medicine at the University of Benin Teaching Hospital in Edo State, Dr. Izegboya Ukpebor, speaks about the cause, symptoms, risk factors and treatment of diphtheria in this interview with ALEXANDER OKERE 

What is diphtheria?

 Diphtheria is a serious bacterial infection caused by the bacterium Corynebacterium diphtheria. There are two types of diphtheria: respiratory and cutaneous diphtheria. Respiratory diphtheria affects the nose, throat, and tonsils. Cutaneous diphtheria affects the skin. The disease is caused by the toxin of the bacterium. This can make people get very sick.

What are the different ways that diphtheria can be transmitted?

Diphtheria bacteria spread from person to person, usually through respiratory droplets, from coughing or sneezing. People can also get sick from touching infected skin lesions like open sores or ulcers, and having contact with contaminated clothing and objects. No significant reservoirs for corynebacterium diphtheria (C. diphtheria) other than humans have been identified.

What happens when the infection occurs?

It is important to note that the pathogenesis of diphtheria is dependent on two primary factors, which are the ability of a given strain of the bacterium to colonise the nasopharyngeal cavity and/or the skin, and its ability to produce diphtheria toxin.

If an individual is infected by the variant of the bacterium that produces a toxin, this can enter the bloodstream and cause damage to the kidneys, heart, and nerves. A person can develop myocarditis, which is inflammation of the heart muscles, and neuropathy. Neuropathy is nerve damage that can result in numbness, muscle weakness, pain, and tingling sensations. Variants of C. diphtheria that do not produce the toxin will result in less severe disease typically causing a sore throat and in rare cases pharyngitis.

Dr Izegboya Ukpebor

Why do the bacteria that cause diphtheria affect the nose and throat the most?

The disease can involve almost any mucous membrane, however, the respiratory system is highly affected because the bacterium is usually spread via airborne droplets after an infected person has coughed or sneezed. Persons nearby may inhale C. diphtheria and it will adhere to the lining of the respiratory system. Other mucous membranes that can be infected with diphtheria include the conjunctiva of the eyes, vaginal tissues, and external ear canal.

What are the common signs of the disease?

Specific signs and symptoms of diphtheria depend on the particular variant of bacterium involved and the part of the body affected. Diphtheria can affect the respiratory system or cause a skin infection. The incubation period is typically two to five days but can be up to 10 days. When there is skin affectation, it could result in sores and ulcers.

How does respiratory diphtheria affect the body?

Respiratory diphtheria can cause difficulty swallowing, sore throat, weakness, neck swelling (swollen glands in the neck), mild fever, appetite loss, red eyes (conjunctivitis), and hoarseness if the disease has affected the larynx. After two to three days, the released toxin kills the healthy tissue in the respiratory system. This results in a thick gray or white coating (pseudomembrane) on the tonsils and or back of the throat with associated difficulty in breathing.

If the membrane extends to the larynx, it results in hoarseness and a barking cough, with the danger of complete obstruction of the airway. If the bacterial affects tissues other than the throat and respiratory system, such as the skin, the illness is generally milder. This is because the body absorbs lower amounts of the toxin, especially if the infection only affects the skin.

How long does it take before the symptoms become visible in an infected person?

The onset of signs and symptoms usually starts after two to 10 days of exposure to the bacteria.

Can an infected person be asymptomatic?

An infected person can be asymptomatic during the incubation period, during convalescence, or for an unknown duration in healthy people. Patients convalescing from diphtheria may harbour the bacteria in the pharynx or nose for many weeks. At this stage, they are called carriers because they can spread the infection without being sick themselves. An asymptomatic carrier of diphtheria is, thus, defined as a patient with no symptoms but with laboratory confirmation of toxigenic C. diphtheria. Untreated people who are infected with diphtheria are usually contagious for up to two weeks and seldom longer than four weeks.

The thick grey coating on the throat of an infected person appears similar to tonsillitis. Is there a connection between the two?

Tonsillitis is an infection (viral or streptococcus bacteria) of the tonsils at the back of the throat. It is a common childhood illness, but teenagers and adults can get it. The tonsils are usually red and swollen. The thick gray coating on the throat associated with diphtheria makes it different from other infections that cause sore throat.

What are the risk factors for diphtheria?

Children and adults who don’t have up-to-date vaccinations are at risk of diphtheria. Other risk factors are living in crowded or unsanitary conditions, travelling to an area where diphtheria infections are more common, immunocompromised state, and sharing utensils with persons suffering from diphtheria.

Does the disease have the same effect on children and adults?

Any of the signs and symptoms can be seen in children and adults.

An outbreak of the disease has been reported in Lagos, Kano, Yobe, and Osun states. Are there factors responsible for its prevalence in those states?

Infected persons in these areas would probably have one or more of the risk factors mentioned earlier. The fact that one person is infected is already a risk factor for close contacts. If these contacts (children and adults) are not vaccinated or fully vaccinated, the disease is further escalated in such environments or communities.

According to the Nigeria Centre for Disease Control, at least 34 deaths have been recorded. Why is the disease that fatal and yet highly preventable and treatable?

The Centre for Disease Control recommends vaccines for infants, children, teens, and adults to prevent diphtheria. This is because the disease has been found to be life-threatening due to the complications that can result from it. The complications include injury to the blockage of the air passages, injury to the heart muscles, injury to the nerves, paralysis, lung infection, or loss of lung function. The disease still exists in areas where vaccinations are not given, like remote areas inaccessible to basic medical care.

A report from the nation’s disease control and prevention agency has indicated more cases are likely, due to “the sub-optimal coverage for the third dose of the diphtheria-containing pentavalent vaccine in the country”.

How is diphtheria diagnosed? What does a doctor look out for?

The doctor looks out for common signs and symptoms highlighted earlier, like fever, swelling of the neck, sore throat, cough, and white or gray coating in the throat. Laboratory testing can be done with a swab taken from the back of the throat, nose, or skin ulcer.

It usually takes time to grow the bacteria, hence, treatment is often started immediately based on a high index of clinical suspicion by the doctor, especially with respiratory diphtheria symptoms.

What is the first step in the treatment of the disease?

The first step is the use of an anti-toxin injection and anti-diphtheric serum. This serves to counteract the toxin produced by the bacteria. This treatment is very important for respiratory diphtheria infections but is rarely used for cutaneous (skin) diphtheria infections.

What are the other forms of treatment?

Antibiotics such as erythromycin or penicillin are given to clear up infections in the respiratory system and on the skin and other parts of the body (like the eyes). Antibiotics may also be prescribed for persons in close contact with the patient. After 48 hours of taking antibiotics, the patients are usually no longer able to infect others. However, it is important to finish the full course of antibiotics to ensure the bacteria are completely removed from the body.

Does treatment require admission of the patient?

During treatment, the patient may be required to stay in the hospital to avoid passing the infection to others. Respiratory diphtheria can lead to death. About one in 10 patients with respiratory diphtheria is likely to die. Without treatment, up to 50 per cent of patients can die from the disease.

How do antibiotics and vaccines work in the treatment of diphtheria?

The use of vaccines is one of the most effective methods of preventing diphtheria. The vaccines are derived from a purified toxin removed from a variant of the bacterium. There are four vaccines that can help to protect against diphtheria. They include DTaP and Tdap, which protect against diphtheria, tetanus, and pertussis (whooping cough); DT and Td, which protects against diphtheria and tetanus.

Modern vaccination schedules include diphtheria toxoid DTaP as a childhood immunisation. The CDC recommends DTaP for those under the age of seven. The schedule is as follows: two months to four months, six months, 15 to 18 months, and four to six years. Those under the ages of 11 to 13 years should receive the Tdap shot, women should receive the Tdap vaccine during the second half of pregnancy, and adults should receive the Td or Tdap every 10 years.

Do vaccines provide permanent protection against the disease?

Five doses of DTaP shot for children and one Tdap shot for preteens are recommended by doctors as the best way to protect against diphtheria. These shots do not offer lifetime protection. People need booster shots to keep up protection.

What is the best form of prevention?

The best form of prevention is vaccination. The Centre for Disease Control recommends that the close contacts of someone with diphtheria receive antibiotics to prevent them from getting sick.

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