Microsporidiosis: epidemiology, clinical data and therapy.

Microsporidiosis is an emerging and opportunistic infection in AIDS patients, organ transplant recipients, children, travelers, contact lens wearers and the elderly. It is associated with a wide range of clinical syndromes of microsporidiosis in humans. The disease is caused by microsporidia, obligate intracellular microorganisms that were recently reclassified from protozoa to fungi. The 14 species of microsporidia currently known to infect humans, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are the most common causes of human infections and are associated with diarrhea and systemic disease. Species of microsporidia infecting humans have been identified in water sources as well as in wild, domestic and food-producing farm animals, raising concerns of water-borne, food-borne and zoonotic transmission. Various molecules have been tested for treating microsporidiosis in humans with variable success. Albendazole is effective against Encephalitozoon species such us Encephalitozoon intestinalis but not against Enterocytozoon bieneusi. This species has shown excellent clinical therapeutic response to direct action with fumagillin, but this drug is toxic when administered systematically to mammals. Its analog, TNP 470, could be promising alternative. Further work is necessary to identify other drugs, which are both effective and devoid of adverse effects.

[Epidemiological and clinical characteristics of intestinal microsporidiosis]. / Caractéristiques épidémiologiques et cliniques de la microsporidiose intestinale chez les immunodéprimés vus à Tunis.

INTRODUCTION: Intestinal microsporidiosis is an opportunistic parasitological infection affecting mainly immunocompromised patients, particularly those infected with HIV. PURPOSE: The purpose of this study was to analyse the epidemiological and clinical characteristics of intestinal microsporidiosis and the treatments available for it. MATERIAL AND METHODS: This retrospective study examined records collected over a 13-year period (from January 1995 through December 2007). It included 572 immunocompromised patients (279 HIV-infected patients and 293 without HIV infection) with symptoms suggesting intestinal microsporidiosis. All were tested systematically for microsporidia spores by modified (Weber's) Trichrome staining. RESULTS: Fourteen patients (10 men, 4 women) were diagnosed with intestinal microsporidiosis, for a prevalence of 2.4% overall, 3.6% in HIV-infected patients and 1.4% in those without HIV infection. Intestinal microsporidiosis affected 10 HIV-infected patients, 70% of whom had a CD4 count <100 cells/mm3. Their mean age was 30+/-15 years (range: 15 months to 48 years). The average age of HIV-infected patients (36 years) was significantly higher than of those without HIV infection (15 years). Thirteen patients had symptoms, most frequently diarrhea (11 cases), sometimes associated with dehydration (5 cases). Eight patients (57%) received only symptomatic treatment, and 4 (28.6%) received albendazole. No treatment was recommended in 2 cases (14.3%). Clinical course was marked by improvement in 6 cases, death in 5, and persistence of asymptomatic carriage in one. Two patients were lost to follow-up. CONCLUSION: Intestinal microsporidiosis is a parasitological disease that mainly affects AIDS patients with CD4 counts <100 cells/mm3. Its diagnosis requires special techniques. Its symptomatology is dominated by chronic diarrhea that can cause dehydration. Effective treatment requires identification of the species.