Electron microscopic diagnosis of intestinal microsporidiosis in Thailand.

Unicellular parasites of the phylum Microspora microsporidia are obligatory intracytoplasmic protozoa with spores containing unique coiled polar filament with extrusion apparatus for injecting infective sporoplasm into host cells. Intestinal microsporidiosis has been recognized as the most common form of microsporidia infection in humans especially in patients with AIDS. To ensure that the appropriate drug regimen is chosen for use against microsporidiosis the parasites species must be accurately determined. The authors report the detection and identification of microsporidia species in 2 HIV-infected Thai men aged 35 and 39 years using transmission electron microscopy (TEM). Both cases had experienced chronic diarrhea and weight loss. TEM analyses of fecal specimens in both cases confirmed the presence of microsporidia spores. The men were treated orally with 1200 mg daily of metronidazole and 800 mg daily of norfloxacin for 7 days without significant improvement. The authors suggest that the given drug dosages may have been too low to effectively cure both microsporidiosis and cryptosporidiosis.