eMedicine Specialties > Ophthalmology > Infectious Disease

Coccidioidomycosis

Author: Cynthia A Self, MD, Assistant Professor, Department of Ophthalmology, Boston University School of Medicine
Coauthor(s): L Raymond DeBarge, MD, Assistant Professor, Department of Ophthalmology, University of Tennessee College of Medicine at Chattanooga
Contributor Information and Disclosures

Updated: Mar 8, 2007

Introduction

Background

Coccidioidomycosis is a disease caused by Coccidioides immitis, a dimorphic fungus that thrives in the lower Sonoran Desert ecozone of the Western hemisphere, including Arizona, New Mexico, west Texas, parts of central America, Argentina, northwest Mexico, and the San Joaquin Valley in California. The warm dry climate and sandy saline soil are ideal for growth of the mycelial phase of the fungus. The mold forms hyphae of 2-4 mm, which consist of chains of arthroconidia that later germinate under moist conditions. During dry seasons, winds spread the highly infectious arthrospores and infection occurs through inhalation of contaminated dust. No documented cases of animal-to-human or human-to-human transmission have occurred.

Pathophysiology

In the pulmonary acinus of the host, the arthroconidia convert to the parasitic phase and form large 20- to 80-mm spherules surrounded by a double-walled capsule. Each spherule contains numerous clear endospores 2-4 mm in diameter. Rupture of a spherule releases the endospores, each of which may form a new spherule.

After inhalation of infectious arthrospores, there is a 10- to 14-day incubation period prior to any clinical manifestations. Coccidioidomycosis is asymptomatic in 60% of patients, while others typically have a limited respiratory illness characterized by fever, cough, and malaise. Bronchopneumonia occurs in approximately one fourth of symptomatic patients. Of every 1000 patients with coccidioidomycosis infection, 2-5 develop disseminated coccidioidomycosis from hematogenous spread of endospores. Disseminated coccidioidomycosis has been found in virtually every organ in the body with the exception of the gastrointestinal tract. The most common site of spread is to the skin.

Because coccidioidomycosis is a fungal disease, the main line of defense is T-cell–mediated immunity. Patients with HIV or other cell-mediated immune deficiencies can develop severe pulmonary and disseminated disease. Pregnant women are also at higher risk for developing disseminated disease. However, primary and disseminated coccidioidomycosis usually occurs in healthy individuals.

Ocular involvement occurs secondary to dissemination and is considered rare. The eyelids and conjunctiva are the most common sites. The skin of the eyelids may contain granulomatous foci of Langerhans giant cells and coccidioidal spherules. Phlyctenular conjunctivitis may be seen and represents a hypersensitivity reaction. True mycotic granulomas of the conjunctiva are less common than hypersensitivity conjunctivitis and usually are seen in the presence of skin lesions.

The uvea is the most common site of intraocular disease. A granulomatous iridocyclitis with iris nodules and posterior synechiae may be seen. However, the typical infection is a multifocal choroiditis with many discrete yellow-white lesions less than a disc diameter in size. Vitritis, vasculitis, serous retinal detachment, and retinal haze may occur in the acute phase. Typical coccidioidal granulomas with spherules are seen in the choroid on histopathology. Lesions also have been noted within the optic nerves. There has been one histopathologically documented report of intraretinal granulomas and organisms that occurred in a previously healthy 12-year-old child.

Frequency

United States

The true incidence of ocular coccidioidomycosis is unknown; however, in one series of 10 patients with disseminated coccidioidomycosis, 4 developed evidence of choroidal infection over a 12-month period of observation.

Disseminated disease has a higher frequency in women during the second half of pregnancy and the postpartum period and in patients who are immunosuppressed.

International

Incidence is unknown.

Mortality/Morbidity

Presenting visual acuity of patients reported in the literature ranges from 20/20 to 20/200. Final visual acuity ranges from 20/20 to no light perception, depending on severity, time to diagnosis, and patient compliance with medical therapy and follow-up care.

Race

Racial differences in the development of ocular manifestations of disseminated coccidioidomycosis are unknown. Ethnic origin is a risk factor for disseminated coccidioidomycosis. The following ethnic groups are listed from the highest to lowest risk: Filipino, African American, Native American, Hispanic, Asian, and white. Filipinos are reportedly 180 times as susceptible as whites to developing disseminated disease.

Sex

A slight male preponderance exists.

Age

Disease may occur in all ages, but infants and elderly persons have the worst clinical outcomes.

Clinical

History

• Past medical history includes the following:
  • Medications
  • Pregnancy
  • Immunosuppression
  • Intravenous drug abuse
  • HIV risk factors
  • A history of travel or living in an endemic area (even remote history)
• Review of systems includes the following:
  • Cough
  • Pleuritic chest pain
  • Fever
  • Chills
  • Night sweats
  • Malaise
  • Myalgia
  • Shortness of breath
  • Skin eruptions
  • Headache
  • Weight loss
  • Joint pain
• Ocular history includes the following:
  • Pain
  • Redness
  • Photophobia
  • Decreased vision
  • Tearing
  • Foreign body sensation
  • Floaters
  • Lid swelling
  • Scotoma

Physical

• Eyelids - Lid granuloma
• Conjunctiva - Phlyctenular or follicular conjunctivitis, conjunctival granuloma
• Sclera - Episcleritis or scleritis
• Cornea - Keratitis, granulomatous mutton-fat keratic precipitates
• Anterior chamber - Cell and flare
• Iris - Nodules
• Lens - Cataract, seclusio pupillae (complete adhesion along the pupillary margin)
• Intraocular pressure - Elevation (secondary glaucoma)
• Vitreous - Vitritis
• Retina - Edema, exudate, hemorrhage, serous retinal detachment
• Choroid - Several groups of findings have been reported, as follows:
  • Diffuse choroiditis (usually seen in preterminal patients)
  • Large (400-1000 µm) juxtapapillary infiltrates involving the choroid with variable involvement of the overlying retina
  • Medium (150-400 µm) spherical opacities at the level of the Bruch membrane and sensory retina
  • Small (100-200 µm) peripheral chorioretinal scars of variable elevation and pigmentation with central hypopigmentation
• Retinal vessels - Vascular sheathing

Causes

The cause of the disease is inhalation of the infectious arthrospores and subsequent dissemination within the body to the eye. A defect in cell-mediated immunity may contribute to the likelihood of dissemination.

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