Microsporidiosis in travelers with diarrhea from the tropics

Microsporidia are protozoa which mainly affect severely immunodepressed AIDS patients in developed countries as well as those in developing ones. Traveler's diarrhea affects approximately 40% of people traveling from industrialized countries to developing ones, and no pathogens are identified in many of those patients on their returning, suggesting that known enteropathogens escape detection or entirely new ones could be responsible. Very few reports of travel-related microsporidiosis have been described.

Between January, 1996 and January, 1998, a total of 40 European travelers from the tropics with a clinical picture of protected diarrhea (three or more loose stools per day lasting for more than 3 weeks) were evaluated. Weber's trichrome modified by Kokoskin stain for microsporidial spores were performed in stool samples of every patient. Microsporidial DNA extraction and PCR amplification were attempted in every stool sample where microsporidial spores were observed.

Four cases of imported Enterocytozoon bieneusi were detected: one HIV-infected short term traveler, a pregnant long term traveler, and two immunocompetent short term travelers. Diarrhea was self-limited, and the spores cleared from the stools in all HIV-non infected travelers, but showed a chronic course in the HIV-infected one.

Available data is too limited to affirm that residence or travel in tropical countries increases the risk for microsporidial infection, but the cases presented here suggest that E. bieneusi could be a cause of self-limited diarrhea in immunocompetent travelers returning from the tropics or could chronically affect immunocompromised HIV-infected travelers.