TABLE 1.

Microsporidial species infecting humans

SpeciesDiscoveryNo. of confirmed reported patientsSite(s) of infection (reference[s])Animal host(s)
HostYrReference(s)Immuno- compromisedaImmuno- competentb
Enterocytozoon bieneusi Human1985 76 >1,000<20Intestine, biliary tract, respiratory tract (322)Vertebrates
Encephalitozoon hellem Human1991 78 <503Eye, respiratory tract, urinary tract, systemic infection (322)Birds
Encephalitozoon intestinalis (originally named Septata intestinalis)Human1993 30, 139<2002Intestine, biliary tract, respiratory tract, bone, skin, systemic infection (322)Mammals
Encephalitozoon cuniculi Rabbit1923 170 <20cSystemic infection, eye, respiratory tract, urinary tract, liver, peritoneum, brain (322)Mammals
Vittaforma corneae (originally named Nosema corneum)Human1990 65, 25813Eye, urinary tract (75, 101, 231)Unknown
Vittaforma-likedHuman2003 278 223Intestine (278)Unknown
Pleistophora ronneafiei (originally named Pleistophora sp.)Human1985 32, 1691eMuscle (169)Unknown
Trachipleistophora hominis Human1996 145 11Muscle, eye (100, 231)Unknown
Trachipleistophora anthropophthera Human1998 305 3Systemic infection, eye (151, 335)Unknown
Brachiola algerae (originally named Nosema algerae)Mosquito1970 304 1f1Eye, muscle (61, 307)Mosquito
Brachiola connori (originally named Nosema connori)Human1974 33, 2731gSystemic infection (273)Unknown
Brachiola vesicularum Human1998 33 1Muscle (33)Unknown
Nosema ocularum Human1991 31 1Eye (31)Unknown
Microsporidium ceylonensis Human1973 11, 12, 361 (unknown)Eye (12)Unknown
Microsporidium africanum Human1981 223 1 (unknown)Eye (223)Unknown
  • a HIV-seropositive persons, AIDS patients, and organ transplant recipients.

  • b Immunocompetent, otherwise healthy.

  • c Two patients with unknown immunostatus, presumably cellular immunodeficiency (see Table 4).

  • d PCR/sequencing results only, needs confirmation.

  • e Cellular immunodeficiency (HIV antibody negative).

  • f Patient was taking immunosuppressive agents for rheumatoid arthritis for decades.

  • g Thymic aplasia.