Human microsporidioses and AIDS: recent advances

Microsporidia, unicellular parasites frequent in animals, were rarely reported in humans before the advent of AIDS. This immunodeficiency syndrome induces the emergence or resurgence of opportunistic infections such as microsporidioses. Since 1985, five species of microsporidia have been found in HIV-infected patients. One of these species was already known in animals whereas all others are new. An increasing number of cases of microsporidioses is detected due to the improvement of methods of diagnosis. According to a study conducted in USA, intestinal microsporidia appear to be the first cause of diarrhea in patients with AIDS. These parasites are intensively investigated as shown by the increasing number of studies published since 1993. Most data concern the diagnosis, pathology, therapy and epidemiology of human microsporidioses as well as the characterization of their agents. Experimental studies aiming to define the immune context of these infections are also reported

Specific and rapid detection of Microsporia in stool specimens from AIDS patients by PCR

Two microsporidian species, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are the cause of diarrhoea and wasting syndrome in AIDS patients. A new PCR assay is proposed for the rapid and specific detection of these parasites in stools

Specific PCR assay for direct detection of intestinal microsporidia Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal specimens from human immunodeficiency virus-infected patients.

A routine assay based on the PCR was developed for the detection of Enterocytozoon bieneusi and Encephalitozoon intestinalis in fecal samples. Two oligonucleotide primer pairs from a conserved region in the small-subunit rRNA genes of E. bieneusi (primer pair V1 and EB450) and E. intestinalis (primer pair V1 and SI500) were used to amplify microsporidian DNA. We achieved specific amplification of a 382-bp DNA fragment in E. intestinalis and a 353-bp DNA fragment in E. bieneusi. Boiling of the samples appeared to be most effective for DNA extraction. Fecal samples containing fewer than 10 microsporidia gave a positive result in the PCR assay. Fecal specimens from 30 human immunodeficiency virus-infected patients with microsporidiosis and fecal specimens from 42 patients suspected of having microsporidiosis were investigated by the PCR assay. The PCR assay was validated against standard staining methods (the Uvitex 2B and Chromotrope 2R staining methods) and immunofluorescence assay specific for E. intestinalis. This comparative study has shown that PCR improved species determination and can thus be considered a fast and reliable method for the detection and identification of each intestinal species

Evaluation of an Immunofluorescent-Antibody Test Using Monoclonal Antibodies Directed against Enterocytozoon bieneusi and Encephalitozoon intestinalis for Diagnosis of Intestinal Microsporidiosis in Bamako (Mali)

A 2-month study was carried out in Mali to evaluate an immunofluorescent-antibody test (IFAT) using monoclonal probes specific for Enterocytozoon bieneusi or Encephalitozoon intestinalis. Sixty-one human immunodeficiency virus (HIV)-seropositive adult patients and 71 immunocompetent children were enrolled. Microsporidia were detected in stools from 8 of 61 patients (13.1%) seropositive for HIV. A single species, E. bieneusi, was identified. All the children were negative for microsporidia. The sensitivity and specificity of IFAT were 100% compared with those of PCR, which was used as the “gold standard.” Moreover, species identification by IFAT was more rapid and less expensive than that by PCR. These results show the suitability of IFAT for detection of microsporidia in developing countries