Reports on HIV/AIDS: 1990

MARCH 23, 1990, MMWR, Vol. 39, No. 11, pp. 188-189
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 [phone].
References
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 laboratory diagnosis of infectious diseases: principles and practice. Vol 1. New York: SpringerVerlag, 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).

42