Pp. 221-275 (55)
Nadia A. El Dib and Thomas Weitzel
Microsporidia the tiny unicellular eukaryotes are intracellular parasites of
almost all animals. The diverged and specialized nature of these organisms, show some
similarity to fungi. They cause opportunistic infections in animals and humans ranging
between asymptomatic and severe life-threatening infections in immunocompromised
individuals. Transmission occurs mainly by oral route, but other methods of
transmission include inhalation, sexual contact, ocular mucosa, wounds, and insect
bites. Food and water are relevant vehicles of infection. Animals act as reservoirs as
they harbor most of the species that can also infect man and might contaminate water
and environment with spores expelled in feces and/or urine. Clinical presentation is
mainly intestinal with chronic diarrhea, mal-absorption, and loss of weight in
immunocompromised persons, and self-limiting diarrhea in the immunocompetent
individuals. Dissemination to other organs, may threaten the life of patients. Clinical
picture of disseminated infection includes fever, cerebral manifestations or some other
unexplained symptoms. Diagnosis of spores in feces, urine, CSF, sputum and in tissue
is difficult and necessitates the use of special stains. Other methods of laboratory
diagnosis include immunofluorescence, Electron Microscopy, and DNA detection.
Treatment with Albendazole is effective for intestinal and other deep infections of
various species of microsporidia except E. bieneusi, where fumagillin, can be
considered. This drug is also used as topical treatment for eye infections by E. hellem
and other species. Trials to produce vaccine against microsporidia are still under study.
The increasing awareness will lead to a better understanding of the epidemiology,
clinical relevance and control of microsporidiosis in humans and animals.
AIDS, Dissemination, Encephalitozoon, Enterocytozoon, HIV,
Microsporidia, Microsporidiosis, Parasitophorous vacuole, Protista, Polar tubule,
Faculty of Medicine, Cairo University, Cairo, Egypt.