Answer to Q1

Diphtheria may present in 2 clinical forms – respiratory (pharyngeal) diphtheria or cutaneous diphtheria. This patient was clinically diagnosed with respiratory/pharyngeal diphtheria because of the pseudo-membrane formation on his tongue and nasopharynx

Respiratory/pharyngeal diphtheria: Mild to moderate disease with localised features and severe disease with systemic features.

• Gradual onset of low-grade fever (rarely >39.5°C) (50-85% of cases) ± chills, malaise, weakness, prostration.
• Sore throat (85%-90% of cases)
• Cervical lymphadenopathy (‘bull neck’) and posterior oro- and naso-pharyngeal respiratory tract pseudo membrane formation (± 50% of cases)
• Serosanguinous or seropurulent nasal discharge, white nasal membrane
• Hoarseness (laryngeal involvement), dysphagia (26%-40% of cases)
• Dyspnoea, respiratory stridor, wheezing, cough

Systemic features include: cardiac (myocarditis and cardiac failure), neurological (soft palate paralysis, cranial nerve palsies or delayed peripheral motor neuropathy) or renal (renal failure)

Cutaneous diphtheria:
Skin lesions are variable in presentation and usually occur on the lower legs, feet and hands. Chronic non-healing ulcers are the most typical manifestation. Secondary bacterial infection is very common and often delays or masks the diagnosis of cutaneous diphtheria.

Adults may be at risk of contracting diphtheria if the organism is present in the community as adult immunity wanes with time following vaccination. Susceptible persons living in crowded conditions are at increased risk of contracting the disease. The patient may have come into close contact with an unimmunized or infected person or handled soiled tissues/materials which were contaminated by discharges from an unimmunized or infected person.

Corynebacterium diphtheriae can be carried in the throat asymptomatically. These persons can also spread the organism through respiratory droplets. Respiratory/pharyngeal diphtheria: Mild to moderate disease with localised features and severe disease with systemic features.

• Gradual onset of low-grade fever (rarely >39.5°C) (50-85% of cases) ± chills, malaise, weakness, prostration.
• Sore throat (85%-90% of cases)
• Cervical lymphadenopathy (‘bull neck’) and posterior oro- and naso-pharyngeal respiratory tract pseudo membrane formation (± 50% of cases)
• Serosanguinous or seropurulent nasal discharge, white nasal membrane
• Hoarseness (laryngeal involvement), dysphagia (26%-40% of cases)
• Dyspnoea, respiratory stridor, wheezing, cough

Systemic features include: cardiac (myocarditis and cardiac failure), neurological (soft palate paralysis, cranial nerve palsies or delayed peripheral motor neuropathy) or renal (renal failure)

Cutaneous diphtheria:
Skin lesions are variable in presentation and usually occur on the lower legs, feet and hands. Chronic non-healing ulcers are the most typical manifestation. Secondary bacterial infection is very common and often delays or masks the diagnosis of cutaneous diphtheria.

Adults may be at risk of contracting diphtheria if the organism is present in the community as adult immunity wanes with time following vaccination. Susceptible persons living in crowded conditions are at increased risk of contracting the disease. The patient may have come into close contact with an unimmunized or infected person or handled soiled tissues/materials which were contaminated by discharges from an unimmunized or infected person.

Corynebacterium diphtheriae can be carried in the throat asymptomatically. These persons can also spread the organism through respiratory droplets.

Question 2: How is the organism transmitted, and what is the incubation period and infectious period?

Answer to Q3

Corynebacterium diphtheriae is not an invasive organism and usually only causes a mild localised inflammatory reaction. The main pathogenic feature of disease is the diphtheria toxin produced only by toxigenic strains. The toxin causes localised tissue necrosis associated with severe inflammation, swelling and ulceration. The hallmark of toxin production is the formation of a leather-like pseudomembrane. The life threatening systemic effects (mainly cardiac effects) of the toxin is caused by the absorption of the toxin into the bloodstream.

Question 4: How do you treat diphtheria?

Answer to Q5

• Isolate all patients with suspected diphtheria until the diagnosis is confirmed or excluded
• Use standard precautions always, contact precautions when the cutaneous form is present (use of gloves and plastic aprons etc.) and droplet precautions for the pharyngeal form (wearing a surgical face mask).
• These transmission-based precautions remain in place until two cultures from the throat and nose (and skin lesions in cutaneous diphtheria) taken at least 24 hours apart after completion of antibiotic therapy are negative for toxigenic C. diphtheriae, C. ulcerans or C. psuedotuberculosis. In the absence of such follow-up cultures, patients should be isolated until they have completed 14 days of antibiotic therapy.
• Where patients are not hospitalised, restrict contact with others until completion of antibiotic therapy.

This suspected case was IMMEDIATELY notified to the Department of Health by completing the new Notifiable Medical Conditions Case Notification Form. Relevant role players were also informed telephonically. Diphtheria is now a category 1 Notifiable Medical Condition hence must be reported within 24 hours of a clinical diagnosis.

Question 6: How is diphtheria prevented and controlled?

Answer to Q7

Management of contacts of persons with diphtheria:

1. Identify ‘close’ and ‘at-risk’ contacts
2. Take a nasopharyngeal swab from all contacts if possible. An oropharyngeal swab is acceptable but not ideal.
3. Administer chemoprophylaxis – all “at-risk” staff members working in emergency department and medical ward received chemoprophylaxis
4. Vaccinate contacts appropriately (depending on vaccination status. All contacts require at least a booster).
5. Monitor contacts for at least 10 days for signs and symptoms.

Contact: In general, the risk for transmission of a droplet spread, infection is increased with very close contact i.e. <2 meters. This includes healthcare workers directly involved with resuscitation including mouth-to-mouth, intubation and suctioning or health care workers who dressed the wounds of a cutaneous case without appropriate infection control procedures. At-risk contacts need to be assessed on a case by case basis by health authorities to determine likely level of risk and need for prophylaxis. Also check vaccination status and catch up on vaccines if indicated.

• Conduct laboratory investigation of close contacts and eligible at-risk contacts
  • Collect nasal and pharyngeal swabs for culture– this should ideally be done before chemoprophylaxis if possible.
• Should a contact test positive for toxigenic C. diphtheriae, the person will require full treatment and follow-up cultures as per symptomatic cases.
  • Precaution should be taken until two cultures (taken at least 24 hours apart from both nose and throat) >24 hours after completing antibiotic therapy are negative for C. diphtheriae.
  • The person will also need to be isolated with standard, contact and droplet precautions; in addition disinfect the immediate environment
• Administer chemoprophylaxis to all close contacts and at-risk contacts to eliminate asymptomatic carriage and to treat incubating disease. Benzyl penicillin or erythromycin/clarithromycin/azithromycin may be used for chemoprophylaxis.