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Epidemiologic Notes and Reports Microsporidian Keratoconjunctivitis in Patients with AIDS

From November 1989 through January 1990, five cases of ocular infections with microsporidia in patients with acquired immunodeficiency syndrome (AIDS) were reported. Three cases were identified in New York City (1), one in San Antonio, and one in Cleveland (2). All five patients were homosexual men aged 29-46 years. The most common presenting manifestations were conjunctivitis or scleritis (all patients), foreign-body sensation (four patients), blurred vision (three patients), and photophobia (three patients). Ophthalmologic examinations found conjunctival inflammation (all patients), decreased visual acuity (four patients), and diffuse punctate keratopathy (four patients). One patient had corneal inflammation, and one patient had corneal ulceration. Pathologic findings were bilateral in all patients. Concomitant, unilateral cytomegalovirus retinitis was noted in two patients. After routine bacterial and fungal cultures failed to identify plausible etiologic agents, corneal or conjunctival scrapings and/or biopsy specimens were obtained from all patients. Sections from these specimens prepared with Giemsa and other routine histologic stains contained numerous oval, dark-staining organisms consistent in morphology with microsporidian spores. Visualization of characteristic ultrastructure with transmission electron microscopy confirmed the diagnosis in all cases.

Two of the five patients have died of other AIDS-related complications. No improvement in their ocular infections was noted before death despite attempted treatment with various topical antimicrobial (tobramycin, chloramphenicol, and sulfisoxazole), lubricating, and anti-inflammatory agents (1). Two other patients did not respond to therapy with topical antimicrobial agents (neomycin, propamidine isethionate, amphotericin, sulfacetamide, and trimethoprim/sulfamethoxazole); however, several weeks after therapy was discontinued the symptoms resolved. The reason for these improvements is unknown, but both patients coincidentally began systemic therapy with fluconozole or itraconazole for concomitant cryptococcal meningitis. Infection in the fifth patient failed to respond to topical preparations (cefazolin, propamidine isethionate, and clotrimazole); one cornea perforated, and the patient underwent emergency corneal grafting.

One patient wore contact lenses; none had histories of ocular trauma. Use of other eye medications by patients is unknown. Two patients had histories of foreign travel. Four patients were exposed to domestic animals: one had cared for a friend's pet cat, two others kept pet birds (parrot and parakeets) in their homes, and one had both a pet cat and a pet bird. The exact source of infection in all five cases remains unknown. Reported by: JM Orenstein, MD, George Washington Univ Medical Center, District of Columbia. J Seedor, MD, New York Eye and Ear Infirmary; DN Friedberg, MD, SM Stenson, MD, PM Tierno, PhD, NC Charles, MD, New York Univ Medical Center, New York City, New York. DM Meisler, MD, CY Lowder, MD, JT McMahon, PhD, DL Longworth, MD, I Rutherford, MD, Cleveland Clinic Foundation, Cleveland, Ohio. RW Yee, MD, A Martinez, MD, F Tio, MD, K Held, MD, Univ of Texas Health Sciences Center, San Antonio, Texas. Parasitic Diseases Br, Div of Parasitic Diseases, Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: Microsporidia are ubiquitous, spore-forming, intracellular protozoal parasites that cause disease in a wide range of vertebrate and invertebrate animals. Manifestations of disease in humans range from asymptomatic infections to fulminant cerebritis and/or nephritis; ocular infections are recognized infrequently (3,4).

Since 1987, microsporidia have been increasingly recognized as a human pathogen (5,6). From 1959 through 1989, only eight cases of microsporidiosis were documented in immunocompetent (six cases) or immunosuppressed (two cases) patients without AIDS; four of these were ocular infections. Since 1985, enteric microsporidial infections have been reported with increasing frequency in AIDS patients with chronic diarrhea; hepatic and peritoneal infections have also been documented. Through 1989, more than 50 cases of intra-abdominal infections were reported in AIDS patients (7). Because reliable serologic tests are unavailable, the diagnosis of microsporidiosis requires biopsy of the infected tissue. Although routine histopathologic studies can provide presumptive identification, diagnostic confirmation requires electron microscopic visualization of the organisms' characteristic ultrastructure. There is no known effective antimicrobial therapy; data on the outcome of surgical procedures, such as keratoplasty and corneal transplantation, are insufficient to permit recommendations.

The occurrence of five cases of ocular microsporidiosis within such a brief time from three diverse geographic areas suggests that this problem (like intestinal microsporidiosis) may be more widespread than previously recognized. Knowledge of the epidemiologic characteristics and clinical features of microsporidial infection is limited. Infections with microsporidia have been documented in immunocompetent and immunosuppressed patients with varied cultural and socioeconomic backgrounds from at least five continents (Africa, Asia, Europe, North America, and South America). However, common epidemiologic characteristics have not been identified (7) and the mode of transmission in humans is unknown. In animals, transmission occurs by ingestion of microsporidian spores shed into the environment through the skin, urine, or feces of infected hosts (3). Although fecal-oral transmission is the likely route of infection in humans with intestinal microsporidiosis, the source of ocular infections is not clear. The relatively superficial location of conjunctival and corneal tissues suggests that direct inoculation of the eye may occur.

To better characterize the epidemiology, public health impact, and clinical features of microsporidial infections, CDC's Parasitic Diseases Branch (PDB), Division of Parasitic Diseases, Center for Infectious Diseases, is interested in obtaining information and specimens from physicians who suspect this condition in their patients. Physicians are encouraged to report such cases to CDC through their state health departments. Consultation and information regarding specimen processing are available through PDB; telephone (404) 488-4050.


  1. Friedberg DN, Stenson SM, Orenstein JM, Tierno PM, Charles NC. Microsporidial keratoconjunctivitis in acquired immunodeficiency syndrome. Arch Ophthalmol (in press).

  2. Lowder CY, Meisler DM, McMahon JT, Longworth DL, Rutherford I. Microsporidia infection of the cornea in an HIV-positive man. Am J Ophthalmol 1990;109:242-4.

  3. Canning EU, Lom J. The microsporidia of vertebrates. New York: Academic Press, 1986.

  4. Cali A, Owen R. Microsporidiosis. In: Balows A, Hausler WJ Jr, Lennette EH, eds. The lab oratory diagnosis of infectious diseases: principles and practice. Vol 1. New York: Springer-Verlag, 1988:929-50.

  5. Bryan RT. Microsporidia. In: Mandell GL, Douglas RG, Bennett JE, eds. Principles and practice of infectious diseases. 3rd ed. New York: Churchill Livingstone, 1990:2130-4.

  6. Shadduck JA. Human microsporidiosis and AIDS. Rev Infect Dis 1989;11:203-7.

  7. Bryan RT, Cali A, Owen RL, Spencer HC. Microsporidia: opportunistic pathogens in patients with AIDS. Prog Clin Parasitol (in press).

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