Isolation of a Microsporidian from a Human Patient

Abstract

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.

Ultrastructural examination of two cases of stromal microsporidial keratitis

“…Initially identified as a new species, N. corneum, infection with this organism was subsequently established in athymic mice and the new taxonomically significant features found warranted placing this organism within a new genus Vittaforma, as V. corneae (Silveria & Canning, 1995a). In the second reported case of V. corneae infection Shadduck et al, 1990;Deplazes et al, 1998) dual microsporidial infection was detected in a patient with AIDS -E. hellem in the sinunasal aspirate, and V. corneae in urine (Deplazes et al, 1998), indicating that V. corneae is capable of dissemination and survival in deep tissues, at least in the immunocompromised host (Silveira et al, 1993). A third case involving V. corneae infection of the corneal stroma in an immunocompetent 65-year-old man has recently been published (Font et al, 2003).…”

“…The first case was of an 11-year-old boy from Ceylon who presented with a scarred and vascularized cornea (Ashton & Wirasinha, 1973) -the organism being named as Microsporidium ceylonensis (Canning & Lom, 1986). Subsequent reports were from a 26-year-old woman from Botswana (Pinnolis et al, 1981) infected with Microsporidium africanum (Canning & Lom, 1986); a 45-year-old man from South Carolina, who had travelled to the Caribbean and Central America Shadduck et al, 1990), infected with Nosema corneum (subsequently renamed V. corneae) (Silveria & Canning, 1995b); a 39-year-old man from Ohio with corneal ulceration, infected with Nosema ocularum (Cali et al, 1991a); a 67-year-old man from Mexico infected with Nosema algera (Visvesvara et al, 1999;Font et al, 2000) and a 65-year-old Caucasian with corneal stromal V. corneae (Font et al, 2003). Further work involving electron microscopy on the original material surviving from the first stromal case (Ashton & Wirasinha, 1973; was unable to establish a generic placement for the organism involved, but attention was drawn to the similarities between M. ceylonensis and Nosema sp.…”

Microsporidia and acquired immunodeficiency syndrome

“…VITTAFORMA Davis et al (1990) have given a case report about a corneal microsporidiosis. This pathogen was named N. corneum by Shadduck et al (1990).…”

“…This pathogen was named N. corneum by Shadduck et al (1990). The investigation of the ultrastructure of the developmental forms in athymic mice (Silveira & Canning 1995) gave rise to the denomination of this agent as V. corneae.…”

Microsporidial Keratoconjunctivitis after Rugby Tournament, Singapore

“…Human ocular microsporidiosis first came into prominence as an opportunistic infection in patients with AIDS in the 1980s and, subsequently, in other immunocompromised patients ( 3 , 4 ). In the 1990s, Vittaforma corneae (formerly known as Nosema corneum ) ( 5 ) was first described as the cause of corneal infection in an immunocompetent person ( 6 ) and disseminated infection in an immunocompromised patient ( 7 ). Since the early 2000s, microsporidial keratoconjunctivitis has been increasingly reported, mostly in Singapore ( 8 – 10 ) and India ( 11 ), among healthy, immunocompetent persons.…”