Historical Perspective

During the mid-1800’s, Louis Pasteur tried to develop preventative techniques needed to stop the spread of pebrine disease, which was threatening to destroy much of the silk industry in France and Italy. Infected silkworms were described by their tegument being covered, or “peppered” with blackish marks and tissues containing oval inclusions. Pasteur recognized the importance of removing infected silkworms and mulberry leaves from silk cultivation farms to prevent further spread of the disease (Wittner, 1999 and Didier et al., 2004).

The agent of pebrine disease was identified by Nägeli in 1857 as the first microsporidian and assigned the name Nosema bombycis. Since this initial discovery and classification, microsporidia have been identified in the infections of many insects, fishes, and mammals and have been implicated as a cause of negative economic impact in associated industries (Didier et al., 2004).

Wright and Craighead (1922) reported the first mammalian microsporidian infection in rabbits by Encephalitozoon cuniculi; affecting neurological systems and causing motor paralysis.

 The first documented case of human microsporidiosis was described by Matsubayashi et al. (1959) in a presumably immunocompetent 9-years old Japanese boy who developed fever, headache, seizures, and loss of consciousness. Organisms identified as Encephalitozoon species were demonstrated in his urine and cerebrospinal fluid and were later determined to be Brachiola connori (Didier, 2005).

Margileth et al. (1973) diagnosed disseminated microsporidiosis in an infant with thymic aplasia. Also, a case of ocular infection was detected in an 11-year-old boy (Ashton and Wirasinha, 1973).

Human cases of microsporidiosis remained infrequent until the mid 1980’s. In 1985, Enterocytozoon bieneusi was established as the etiological agent of diarrheal disease in an AIDS patient, and, thereafter, cases of microsporidiosis became more frequently detected in immunocompromised individuals (Desportes et al., 1985).

Currently, cases of microsporidiosis have been described in immunocompromised individuals, including HIV/AIDS patients, organ recipients and cancer patients undergoing chemotherapeutic treatments. Additionally, intestinal microsporidiosis has been identified in immunocompetent individuals, including the very young, elderly, travelers, and contact lens wearers (Didier et al., 2004).