Diphtheria Disease

BASICS

DESCRIPTION

Acute respiratory tract infection caused by Corynebacterium diphtheriae, usually producing a membranous pharyngitis

Incubation period 2 to 5 days. Infection usually occurs in fall and winter in temperate regions. In the tropics, seasonal trends are less distinct.
Transmission by respiratory route from infected person or carrier. Humans are the only reservoir.
Several forms occur:
- Membranous pharyngotonsillar diphtheria - the membrane is gray, adheres to the pharynx and is surrounded by erythema. The underlying mucosa bleeds when the membrane is removed.
- Nasal diphtheria - unilateral discharge
- Obstructive laryngotracheitis - complication when membrane descends into larynx or bronchial tree. When it breaks up in young children, total obstruction of the airway may occur.
- Cutaneous diphtheria - punched-out ulcer covered by gray membrane (particularly in tropics and among homeless). Peaks August to October in southern United States.
System(s) affected: Pulmonary, Skin/Exocrine, Cardiovascular, Nervous
Genetics: N/A
Incidence/Prevalence in USA: 1.6 in 100,000,000 for non-cutaneous form
Predominant age: Children less than 15 and poorly immunized adults. Diphtheria is a rare condition in the U.S. today. Recent outbreaks have occurred in the new independent states of the former Soviet Union.
Predominant sex: Male = Female

SIGNS AND SYMPTOMS

Membranous pharyngotonsillar diphtheria:
- Initially, white to yellow membrane which is easily removed
- Adherent, whitish-gray, leathery membrane on tonsils or pharynx
- Removing membrane causes bleeding of mucosa
- Injected pharynx
- Membrane may become black due to hemorrhage
- Sore throat
- Cervical adenopathy with swelling
- Malaise and prostration
- Enlarged, tender cervical and submandibular lymph nodes
- May progress to edematous, swollen neck (bull neck)
- Paralysis of soft palate
- Low grade fever of 37.8-38.8°C (100-100.9°F)
- Thrombocytopenia and purpura
Nasal diphtheria:
- Serosanguineous or seropurulent discharge and excoriations
- Often discharge is unilateral
- Often chronic, mild course
Obstructive laryngotracheitis:
- Hoarseness
- Croupy cough
- Progresses to dyspnea and stridor
- Labored breathing
- Thick speech
Cutaneous diphtheria:
- On skin, conjunctiva, vulva, vagina, penis
- Primary cutaneous diphtheria - starts as tender pustule on lower extremity and becomes deep, round, punched-out ulcer covered by grayish membrane
- Secondary infection of preexisting wound - purulent exudate, partial membrane

CAUSES

Corynebacterium diphtheriae

RISK FACTORS

Crowded living conditions
Inadequate immunization. In the USA, 22-62% of people age 18 to 39 years and 41-84% of people over 60 years of age lack protective levels of antibody.
Lower socioeconomic status
Native Americans
Alcoholism
Travelers - outbreaks have occurred in the Ukraine and Russia

DIAGNOSIS

LABORATORY

Gram-positive rods in the pathognomonic Chinese character configuration
Moderate leukocytosis
Thrombocytopenia
Transient albuminuria
Methylene-blue stains can assist in a presumptive diagnosis in experienced hands
Culture from nose and throat beneath membrane and have plated on special media; inform lab that diphtheria is suspected
Should test for toxigenicity of strain

Drugs that may alter lab results: If an antibiotic was used, then 5 or more days may be required for the culture to grow on Loeffler's medium
Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS

Pleomorphic gram-positive rods
Necrotic epithelium
Hyaline degeneration

SPECIAL TESTS

Serial ECG's and cardiac enzymes to detect myocarditis
Delayed peripheral nerve conduction velocities
Culture on Loeffler's or tellurite medium is positive in 8 to 12 hours if not previously treated with an antibiotic. Laboratory must be alerted to use one of the special media.

IMAGING

N/A

DIAGNOSTIC PROCEDURES

Culture throat or lesions
Smear of exudate for gram stain

TREATMENT

APPROPRIATE HEALTH CARE

Inpatient, initially hospitalized in unit which can monitor cardiac and respiratory status. (Must act on presumptive diagnosis because therapy cannot wait for culture confirmation).
Isolation until cultures on two consecutive days are negative. The first culture must be taken at least 24 hours after the cessation of antibiotic therapy.

GENERAL MEASURES

Have intubation or tracheostomy readily available. For laryngeal disease, laryngoscopy is desirable. Intubation or tracheostomy should be considered early for laryngeal disease.
Avoid hypnotics and sedatives while monitoring respiratory status
Physical therapy in convalescence for range of motion exercises to prevent contractions

SURGICAL MEASURES

N/A

ACTIVITY

Rest (for at least 3 weeks until risk of developing myocarditis has passed)

DIET

Liquid to soft as tolerated

PATIENT EDUCATION

Explain aspects of illness and complications

FOLLOW UP

PREVENTION/AVOIDANCE

Prevention is by immunization:
- Children 6 weeks up to 7 years of age should receive doses at 2, 4, 6 and 15-18 months of age with 0.5 mL of DTaP vaccine IM. If the pertussis component is contraindicated then pediatric DT should be used. A booster dose should be given at 4-6 years of age and again at age 11-12 or 14-16 years.
- Unimmunized persons 7 years of age or older should receive two doses of Adult Td 4-8 weeks apart with a third dose 6-12 months later. 0.5 mL of Td should be given IM.
- Subsequently, booster doses with Td should be given every 10 years to all individuals without a contraindication. An alternative strategy after the booster at age 11-12 or 14-16 years is a single adult booster at 50 years of age, in addition to following the recommendations for Td boosters in the event of an injury or wound.
- Immunized individuals may develop diphtheria but their course is milder; immunization protects against the toxin, not infection or microbial carriage in the nose, pharynx or skin.
- Disinfect all articles in contact with patient
- Close contacts should be cultured and given antibiotic prophylaxis regardless of immunization status. Previously immunized contacts should receive a booster of diphtheria toxoid. Unimmunized contacts should begin the series. Erythromycin prophylaxis for 7 days.

POSSIBLE COMPLICATIONS

Myocarditis (in 10-25%) may occur early
Cranial and peripheral neuropathy (2-6 weeks after onset)
ECG abnormalities in two-thirds of patients, including: bundle branch block, tachycardia, atrial or ventricular fibrillation, extrasystoles
Right sided heart failure
Local paralysis of soft palate and posterior pharynx demonstrated by regurgitation of fluids through the nares
Peripheral and cranial neuropathy affecting primarily motor nerve functions. Motor dysfunction starts proximally and extends distally. Usually slowly resolves.
Syndrome like Guillain-Barré

EXPECTED COURSE AND PROGNOSIS

< 5% mortality rate
Prognosis guarded until recovery
5-10% persistence in nasopharynx in convalescing patients

MISCELLANEOUS

ASSOCIATED CONDITIONS

N/A

AGE-RELATED FACTORS

Pediatric: N/A
Geriatric: N/A
Others: N/A

PREGNANCY

N/A

OTHER NOTES

N/A

ABBREVIATIONS

N/A

Clinical Investigations

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