Ophthalmologic Manifestations of Diphtheria

The name diphtheria is derived from the Greek root for leather, which is descriptive for the pharyngeal membrane that characterizes the disease. Although its symptoms have been discussed by many authors of ancient and modern times, diphtheria has been known by its present name only since Bretonneau published a treatise in 1823. Hippocrates clinically described it, and, in the 20th century, diphtheria evolved from a major public health problem to a medical curiosity within the developed nations through the use of immunization measures.

Conjunctivitis diphtheritica has the property of exciting profuse exudation in the tissue of the conjunctivae, which has a great tendency to coagulate, leading to necrosis of the infiltrated tissue.

Diphtheria is an acute infectious disease caused by the gram-positive bacillus Corynebacterium diphtheriae. It is characterized by a primary lesion, usually within the respiratory tract, and more generalized symptoms caused by release and spread of bacterial exotoxins throughout the body. Diphtheria most commonly affects children younger than 10 years. Humans are the only known reservoir for C diphtheriae. The primary modes of spread are via airborne droplets or contact with respiratory secretions or exudates from infected skin lesions. Fortunately, the widespread immunization of infants using diphtheria toxoid has made this infection extremely rare in developed nations.[1] Diphtheria was the leading cause of death in Canadian children aged 2-14 years only 75 years ago.

The primary pathological lesion of diphtheria is the development of a thick leathery membrane consisting of bacteria, dead cells from the mucous membranes, and fibrin. This membrane, surrounded by a narrow zone of inflammation, firmly adheres to the underlying tissues. Removal of this membrane reveals a bleeding edematous submucosal tissue. The membrane may be localized or extend widely, forming a cast of the pharynx and the tracheobronchial tree. Soft tissue edema of the airways can compromise respiratory function, and death by suffocation from soft tissue edema and aspiration of the membrane is common.

The major virulence of C diphtheriae results from the action of its potent exotoxin, a polypeptide chain produced at the site of the local lesion that passes into the bloodstream. The toxin, which inhibits protein synthesis in mammalian cells, affects all cells in the body but most prominently the heart, producing myocarditis[2] ; the kidney, resulting in renal tubular necrosis; and the nervous system, resulting in demyelination. Toxic demyelination occurs in 10% of all infected patients. The neuropathy usually occurs 2-6 weeks after infection, but it may be delayed for up to 3 months after primary infection.

Frequency

United States

At the turn of the century, in the United States, diphtheria was extremely common, occurring primarily in children, and it was one of the leading causes of death in infants and children. In the 1920s, when data were first gathered in the United States, there were approximately 150,000 cases and 13,000 deaths reported annually. After diphtheria immunization was introduced, the number of cases gradually fell to about 19,000 in 1945. When diphtheria immunization became widespread in the late 1940s, a more rapid decrease in the number of cases and deaths occurred.

From 1970-1979, an average of 196 cases per year were reported. Seventeen outbreaks of 15 or more cases occurred in the United States from 1959-1980, but there have been no outbreaks of multiple cases since 1980. From 1980-1989, the number of individual cases in the United States dropped to 24; 2 cases were fatal, and 18 occurred in persons aged 20 years or older. From 1990-2000, an additional 28 cases were reported, most having occurred in nonimmunized (or inadequately immunized) individuals, particularly those who travel to areas outside the United States where diphtheria is common and those who come into close contact with travelers from such areas.

Since 2000, 5 or fewer cases have been reported annually in the United States. Between 2004 and 2008, no cases of diphtheria were recorded in the United States.

International

The disease remains endemic in many parts of the third world, although decreases in incidence have occurred worldwide.

Epidemic diphtheria reemerged in the New Independent States (NIS) of the former Soviet Union, beginning in the Russian Federation in 1990 and affecting all 15 NIS by the end of 1994. Approximately 90% of all diphtheria cases reported worldwide during 1990-1995 were reported from the NIS. From 1990-1995, approximately 125,000 cases of diphtheria and 4000 deaths related to the disease were reported in the NIS.

At the time of the disintegration of the former Soviet Union in 1991, all NIS relied on supplies of vaccine and antitoxin from Russia, and most lacked the financial resources to procure them from the international market. Mass vaccination campaigns began in 1994, and they have been successful in controlling this epidemic.

In 2003, the World Health Organization reported 50 cases, including 3 in a resettlement camp for displaced persons in Kandahar. A mass vaccination campaign targeting the entire population of the camp (c. 40,000) was launched.

A diphtheria outbreak was reported in May 2010 in Haiti, in one of the settlements housing people displaced by the January 2010 Haitian earthquake. Prior to that, in October, 2009, another diphtheria outbreak in Haiti caused 11 cases and 5 deaths over a 4-week period.

A diphtheria outbreak of 98 cases occurred from February to November 2011 in northeastern Nigeria. There was a 21% fatality rate, primarily in young children. Low rates of immunization, delayed clinical recognition of diphtheria, and absence of treatment with antitoxin and appropriate antibiotics contributed to this epidemic and its severity.

Mortality/Morbidity

The potent diphtheria exotoxin can cause myocarditis, renal tubular necrosis, or toxin demyelination of the central nervous system.

Age

Children younger than 10 years more commonly are affected.

The epidemic in the New Independent States of the former Soviet Union in 1990-1995 was characterized by a high proportion of cases among adults.

The prognosis is favorable if detected early in the disease.

Diphtheria begins as a respiratory infection with strident coughing and fever.

Ocular manifestations of diphtheria, as those involving other organ systems, are both a result of the primary infection (keratoconjunctivitis) and the release of exotoxin (motility disorders).

In the eye, conjunctival infection may be mild, resembling a viral conjunctivitis with preauricular adenopathy, palpebral and bulbar conjunctival erythema and edema, and a moderate amount of yellowish discharge.

The more typical diphtheric infection is that of membranous conjunctivitis. Infiltration of the conjunctival surface leads to extreme edema and erythema of the eyelids with increasing stiffness of the lids. Membrane formation occurs over the palpebral and bulbar conjunctivae, and the membrane ultimately becomes necrotic and sloughs off, leaving behind severe conjunctival scarring with formation of symblepharon, entropion, trichiasis, and tear production disturbances. The conjunctiva may become necrotic, and thrombosis of perilimbal vessels can lead to corneal ulceration and scarring and to corneal perforation from corneal ischemia.

Up to 25% of patients with severe primary disease develop neurotoxicity from the effects of the exotoxin. Local paralysis of the soft palate and posterior pharyngeal wall are most common with other cranial neuropathies, leading to oculomotor and ciliary paralysis and facial and laryngeal weakness. Peripheral neuropathy may occur 10 days to 3 months postinfection, with proximal motor neuropathy initially, then moving distally, commonly involving dorsiflexors of the foot.

Oculomotor palsy and abducens palsies may be unilateral, bilateral, complete, or incomplete. Facial nerve paralysis may cause difficulties with eyelid closure. Paralysis of accommodation is common, occurring in approximately 10% of patients with diphtheria. Pupillary reactions remain normal. Usually, resolution of these cranial neuropathies occurs spontaneously within 2-6 weeks.

Diphtheria is an acute infectious disease caused by the gram-positive bacillus C diphtheriae.

With severe respiratory involvement, death can occur.

Optic neuritis has been reported as a possible rare complication of diphtheria immunization.

Gram and Wright stains of the conjunctival secretions should be obtained.

Treatment includes supportive care and isolation, as well as penicillin or erythromycin, which are extremely effective against C diphtheriae.

Diphtheria antitoxin, a hyperimmune antiserum produced in horses, protects against neurotoxicity when given within the first or second day of the illness. Prevention is accomplished by immunization with formalin-inactivated toxin, usually given within the first year of life.[3]

Additional treatment of primary ocular infection includes topical erythromycin ointment, frequent manual removal of infected membranes, and ocular lubrication. Topical steroids may be used to reduce inflammation if no corneal ulceration is present.

From 1991 through 1998, there was a massive epidemic of diphtheria in the Independent States of the Former Soviet Union, representing the first large-scale diphtheria outbreak in developed countries in more than 30 years. This occurred because of vaccine shortages and laxity in diphtheria immunization programs. Beginning in 1995, aggressive control strategies were implemented through mass vaccination with diphtheria toxoid, resulting in a major decrease in new cases of diphtheria by 2000.

The availability of vaccines in the United States is now threatened by systemic problems in the development, purchase, and distribution of vaccines. The number of companies that produce vaccines for the United States has declined markedly since the 1960s, and today, only 5 companies produce all routine vaccines for this market. There is only one supplier for measles, mumps, and rubella (MMR); diphtheria, pertussis, and tetanus (DPT); and polio; and if this supplier ceases production, it could take years to have a replacement vaccine licensed and publicly available.[4]

Patients should receive follow-up care until the conjunctivitis is resolved.

Treatment includes supportive care and isolation, as well as penicillin or erythromycin, which are extremely effective against C diphtheriae.

Diphtheria antitoxin, a hyperimmune antiserum produced in horses, protects against neurotoxicity when given within the first or second day of illness. Prevention is accomplished by immunization with formalin-inactivated toxin, usually given within first year of life.

Additional treatment of primary ocular infection includes topical erythromycin ointment, frequent manual removal of infected membranes, and ocular lubrication. Topical steroids may be used to reduce inflammation if no corneal ulceration is present.

Class Summary

Empiric antimicrobial therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.

Penicillin G benzathine (Bicillin LA)

Interferes with synthesis of cell wall mucopeptides during active multiplication, which results in bactericidal activity. Effective treatment for systemic diphtheria.

Erythromycin

Inhibits bacterial growth, possibly by blocking dissociation of peptidyl t-RNA from ribosomes causing RNA-dependent protein synthesis to arrest.

In children, age, weight, and severity of infection determine proper dosage. When bid dosing is desired, half-total daily dose may be taken q12h. For more severe infections, double the dose. Effective treatment for systemic diphtheria

Erythromycin ophthalmic (E-Mycin)

Indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections. For local control of diphtheric involvement of eye

Class Summary

Have anti-inflammatory properties and cause profound and varied metabolic effects.

Prednisolone acetate 1% ophthalmic drops (Pred Forte)

Decreases inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability. To be used to minimize membrane formation and scarring. To reduce inflammation in the eye(s)