title: Latent microsporidiosis caused by Encephalitozoon cuniculi in immunocompetent hosts: a murine model demonstrating the ineffectiveness of the immune system and treatment with albendazole.
abstract: BACKGROUND
  Microsporidia are obligate intracellular parasites causing severe infections with lethal outcome in immunocompromised hosts. However, these pathogens are more frequently reported as latent infections in immunocompetent individuals and raises questions about the potential risk of reactivation following induced immunosuppression.
  
  
  OBJECTIVE
  To evaluate the possibility latent microsporidiosis, efficacy or albendazole, and reactivation, the authors monitored the course of E. cuniculi infection in immunocompetent BALB/c mice and immunodeficient SCID mice using molecular methods.
  
  
  METHODS
  Mice were per orally infected with 10(7) spores of E. cuniculi. Selected groups were treated with albendazole, re-infected or chemically immunosuppressed by dexamethasone. The presence of microsporidia in the host's organs and feces were determined using PCR methods. Changes in numbers of lymphocytes in blood and in spleen after induction of immunosuppression were confirmed using flow cytometry analysis.
  
  
  RESULTS
  Whereas E. cuniculi caused lethal microsporidiosis in SCID mice, the infection in BABL/c mice remained asymptomatic despite parasite dissemination into many organs during the acute infection phase. Albendazole treatment led to microsporidia elimination from organs in BALB/c mice. In SCID mice, however, only a temporary reduction in number of affected organs was observed and infection re-established post-treatment. Dexamethasone treatment resulted in a chronic microsporidia infection disseminating into most organs in BALB/c mice. Although the presence of E. cuniculi in organs of albendazole- treated mice was undetectable by PCR, it was striking that infection was reactivated by immunosuppression treatment.
  
  
  CONCLUSIONS
  Our results demonstrated that microsporidia can successfully survive in organs of immunocompetent hosts and are able to reactivate from undetectable levels and spread within these hosts after induction of immunosuppression. These findings stress the danger of latent microsporidiosis as a life-threatening risk factor especially for individuals undergoing chemotherapy and in transplant recipients of organs originating from infected donors.
authors.affiliation: Institute of Parasitology, Biology Centre of Academy of Sciences of Czech Republic, v.v.i., Ceské Budejovice, Czech Republic.
authors.forename: Michaela
authors.initials: M
authors.lastname: Kotkova
authors.forename: Bohumil
authors.initials: B
authors.lastname: Sak
authors.forename: Dana
authors.initials: D
authors.lastname: Kvetonova
authors.forename: Martin
authors.initials: M
authors.lastname: Kvac
mesh_terms: D015766:Albendazole / Q000627:therapeutic use*; D000818:Animals; D002522:Chlorocebus aethiops; D003907:Dexamethasone; D004195:Disease Models, Animal; D009670:Encephalitozoon cuniculi; D016890:Encephalitozoonosis / Q000188:drug therapy* / Q000276:immunology*; D005243:Feces / Q000382:microbiology; D005434:Flow Cytometry; D018655:Lymphocyte Count; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D016133:Polymerase Chain Reaction; D014709:Vero Cells; D014781:Viscera / Q000382:microbiology
chemical_list: D003907:Dexamethasone; D015766:Albendazole