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Parasitología al día

versión impresa ISSN 0716-0720

Parasitol. día v.21 n.3-4 Santiago jul. 1997 


Enterocytozoon bieneusi (ORDEN MICROSPORIDIA,

FAMILIA Entrerocytozoonidae) IN COSTA RICA:






The first case of microsporidiosis in Central America is described in an AIDS patient from Costa Rica. Electronic microscopy studies indicate that the spores were not included in a parasitophorous vacuola, but they are in direct contact with the cell cytoplasm. Sporogonic proliferative plasmodial forms presence ana localization of the polar tubes in the anterior region of the spore, confirmed the specie Enterocytozoon bieneusi as the cause of this microsporidian infection.

Key words: Enterocytozoon bieneusi; Microsporidiosis; AIDS, Costa Rica.

*Centro de lnvestigación en Enfermedades Tropicales (CIET) y Departamento de Parasitología, Facultad de Microbiología, Universidad de Costa Rica **Hospital Nacional de Niños.
***Servicio de Hemato-Oncología, Hospital San Juan de dios, Caja Costarricence del Seguro Social San José, Costa Rica, América Central.



Arrival of AIDS entailed the invasion to human beings of some organisms normally infecting insects and low animals. That is the case of microsporidian infections found specially in intestin, eyes and in some exceptions, in other organs.1 The first specie was Enterocytozoon bieneu2 followed by Encephalitozoon hellem3 and later, genus Nosema, Pleistophora, Microsporidium,1 Septata,4 classified later as Encephalitozoon.5 Recently a new specie, Trachipleistophora hominis has been isolated fromn en AIDS patient.6

In Latin.American, countries there are reports of these organisms in Chile 7,8 and Argentina9 and thus far there are not reports of microsporidian infections in Central America.

Studying the faeces of an AIDS patient with some intestinal problems, we found spores similar to those of Microsporidia parasites. The classification of that organism is the  aim of this paper.



Patient studied for this report was a caucasian, 37 years old male with no history of drug abuse. Voluntary underpass en anti-HIV test eight years ago that was positive by ELISA and confirmed by Western Blot. He did not present any symptoms at that time and his CD4 total account was 640 per mm3 an received no treatment at all.

Two years later he presented low fever (37.8 to 38.3ºC) for one month and without medical consultation he took acelaminophen for control that fever. When he was first seen the clinical findings was a right supraclavicular adenopathy, painfull at touch and measuring 3x2 cm. The lymph node was taken out for pathological study and the next day a ganeralized purulent celulitis could be detected all oven this chest; pathological and bacteriological diagnosis of ganglionar tuberculosis was then established, his CD4 account 50 per mm3 and stayed in this level for the next 5 years. He recived treatment with isoniocide, rifampicine, piracinamide and etambutol and he was considerd cured of the Mycobacterium infection after 3 months. He remained with this treatment for another one an a hall year and started to receive AZT (400 mg per day) and preventive treatment with trimetropinsulfametoxasol and ketoconazol.

No diarrea, cough or other symptoms were reported until one year later when he presented genital Herpes lesions that were succesfully treated with aciclovir, and bilateral nose lesion that was diagnosed as sporotricosis. He did not respond to treatment with fluconazole neither with amphotericine B and he started with severe diarrea that was the reason for this repot.

A fecal sample of this patient was studied for direct examination and then stained by the microsporidian specific method.10 Briefly, smears are fixed with formalin and methyl alcohol, stained with a mixture of chromotrope 2R, fast green and phosphotungstic acid, differentiated with acid ethyl alcohol, dehydrated and mounted as usual. Portions of mucosa found in faeces of the patient were fixed and stained by the haematoxilin-eosin method. For specific identification conventional electronic microscopy studies were done to compared with previous works.11-14



Studies with electron microscopy, showed thatr the spores were in direct contad with the cell cytoplasma and not in a parasitophorous vacuole (Figure 1). In addition we observed sporogonic proliferatives plasmodial form (Figure 2), and polar tubes (PT) situated all togheter in the anterior region of the spore (Figure 3). Other details, such as lamelar polaroplast (LP) and the ribosomes (R) close to the anchor apparatus (AA) were shown (Figure 4).


Although microsporidian has been reported in many countries around the world,1 there is not any information about these parasites in Central America. Therefore this is the first report of the presence in Costa Rica of E. bieneusi in an AIDS patient. It is interesting to observe that symptomatology in this person was extremely severa, including mucosa elimination in the faeces which shown an intense epithelial degeneration as has been demonstrated.1 The specific diagnosis of E. bieneusi was established on the basis of the presence of the plasmodial forms, the absence of a parasitophorus vacuola housing the parasite and the apical, non peripheral localization of the polar tube (Figure 3), all characteristics previously described for this specie.11, 15

E. bieneusi is the principal etiologic agent of human microsporidiosis,1 specially in HIV infected persons. Since in Costa Rica there are around 25.000 AIDS patients16 it is possible to find more cases due to this parasite. In fact in a survey of 54 AIDS patients we have found several persons carrying microsporidial spores (non published data). Since this specie has also been found in HIV negative people,14 we can suspect that many other cases could be present and they must be controlled.



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Acknowledgements. This work was supported in part by grants # 803-97-262 and # 803-97-264 of the Vicerrectoría de Investigación, University of Costa Rica. The authors thank Dr. Olga Arroyo for the electronic microscopy preparations.

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