ELECTRON-MICROSCOPY AS AN ESSENTIAL TECHNIQUE FOR THE IDENTIFICATION OF PARASITES IN AIDS PATIENTS

We use EM with increasing frequency for the identification of opportun istic parasitic infections in HIV-infected individuals. Apart from Pne umocytis carinii, Toxoplasma, Cryptosporidium, and Leishmania, we stud ied several aspects of microsporidiosis. Infection with the intestinal microsporidian Enterocytozoon was found in as much as 27% of AIDS pat ients with chronic diarrhoea without other pathogens. EM diagnosis of microsporidiosis is commonly performed on intestinal biopsies, but we have recently demonstrated spores of microsporidium with a non-invasiv e technique, viz. in faeces (1). However, EM of biopsy material remain s the reference technique to distinguish the various species. Combinin g faeces and biopsy examination, we identified another group of micros poridians, Encephalitozoon sp., in the small intestine of AIDS patient s with chronic diarrhoea (Fig. 1). Encephalitozoon sp. with identical ultrastructure was found in urine and sinus discharge, suggesting diss emination of the infection. In the maxillary sinus of one patient, we demonstrated E. bieneusi, a parasite which had previously been found o nly in small intestine and bile duct epithelium (2) (Fig. 2). After al bendazole treatment, Encephalitozoon sp. disappeared from faeces, urin e and nasal discharge. Although ultrastructural damage was noted in th e developmental cycle of E. bieneusi in biopsies after treatment with albendazole, spores continued to be present in the faeces. These resul ts demonstrate the great value of EM in the diagnosis of several paras itic diseases, especially microsporidiosis.