Isolation of a microsporidian from a human patient.

Several genera of microsporidia have been identified morphologically in human tissue but none has yet been propagated in vitro. These primitive, obligate intracellular parasitic protozoa are poorly understood pathogens of a wide variety of vertebrates and invertebrates. In humans they are especially important as opportunistic pathogens in AIDS patients. A microsporidian was recovered from a human patient and propagated in vitro. The organism has diplokarya, divides by binary fission, and often is found free in the host cell cytoplasm. The name Nosema corneum is suggested.