Unapparent microsporidial infection among immunocompetent humans in the Czech Republic

Abstract

In the present population-based study, we determined the prevalences of the most common human-pathogenic microsporidia, Encephalitozoon spp. and Enterocytozoon bieneusi, in asymptomatic healthy people living in the Czech Republic. A total of 382 males and females (ages, 1 to 84 years) living in the Czech Republic, of whom 265 were Czech nationals and 117 were foreign students, were included in a study testing for the presence of microsporidia by use of coprology and molecular methods. Single-species infections with Enterocytozoon bieneusi or an Encephalitozoon sp. were detected for 9 and 136 individuals, respectively. Moreover, coinfections were detected for 14 individuals. Four genotypes of 3 human-pathogenic Encephalitozoon spp. and 7 E. bieneusi genotypes, including 3 novel genotypes, were detected. Some of these were reported in humans for the first time. The highest prevalence was recorded for individuals older than 50 years and for loose, unformed stool samples. These findings clearly show that exposure to microsporidia is common among immunocompetent people and that microsporidiosis is not linked to any clinical manifestation in healthy populations.

Fig. 1.

NJ tree based on SSU rDNA sequences of 106 Enterocytozoon bieneusi isolates, including our three new sequences CZ1, CZ2, and CZ3 (arrows). Genotypes previously found in humans are shaded. The six most divergent sequences (DQ683749, DQ885588, AY237209, AY237210, AY237211, and DQ885585) are not shown in the tree and were used as an outgroup to root the branch of all other isolates. Bootstrap values are given at the nodes.