Enterocytozoon bieneusi
Wei Li ,1
Yaoyu Feng ,2,3,
* and Lihua Xiao 2,3,
*
1
Heilongjiang Provincial Key Laboratory of Zoonosis, College of Veterinary Medicine, Northeast Agricultural University, Harbin, China
2
Center for Emerging and Zoonotic Diseases, College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
3
Guangdong Laboratory for Lingnan Modern Agriculture, Guangzhou, China
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Enterocytozoon bieneusi is a microsporidium, related to Cryptomycota and fungi, which has been reported globally in
a wide range of mammalian and avian hosts. It is responsible for over 90% of documented cases of human
microsporidiosis and causes varying clinical symptoms, typically diarrhea and wasting. Infection begins with ingestion of
spores in contaminated water and food. Spores deliver the infective sporoplasm into host enterocytes via the discharged
polar tube. Meronts form and develop into multinucleated plasmodia, which undergo sporogony to form sporoblasts and
then mature spores. Spores released from infected cells are shed with the stool. Sequence analysis of the ribosomal internal
transcribed spacer (ITS) has identified over 500 genotypes, some of which are generalists of zoonotic importance
and pose a threat to public health. Population genetic data uphold the zoonotic nature and host specificity of the parasite.
Knowledge of its pathogenicity, immune responses, and expanded treatment options are urgently needed.
KEY FACTS:
E. bieneusi has a compact genome of
~6 Mb and relies on the host for basic
nutrients and energy metabolism.
Effective cultivation methods and animal
models are not yet available, leading to
poor understanding of its biology and
pathogenesis.
The small, hardy environmental spore
(~1 μm) facilitates waterborne and
foodborne transmission.
There is a high genetic diversity of isolates,
with over 500 genotypes; they form 11
groups in phylogenetic analysis, with genotypes
in Group 1 of major zoonotic
concern. Multilocus genotyping of isolates
generates discordant results, indicating the
occurrence of genetic recombination.
DISEASE FACTS:
Microsporidiosis by E. bieneusi is most
severe in immunocompromised persons.
Heavy infection causes villus atrophy
and crypt hyperplasia of the small
intestine, leading to malabsorption.
Diarrhea and wasting are the most
common clinical manifestations, but the
infection can be asymptomatic in
immunocompetent individuals.
Foodborne, waterborne, and
nosocomial outbreaks have been
reported in industrialized nations.
Infection is mostly diagnosed by
detecting spores or DNA in stools
through microscopy or PCR.
Treatment with oral fumagillin is effective,
but causes thrombocytopenia, and
better commercially available therapeutic
agents are needed.
TAXONOMY AND CLASSIFICATION:
PHYLUM: Microsporidia
CLASS: Microsporea
ORDER: Chytridiopsida
FAMILY: Enterocytozoonidae
GENUS: Enterocytozoon
SPECIES: E. bieneusi
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*Correspondence:
yyfeng@scau.edu.cn (Y. Feng) and
lxiao@scau.edu.cn (L. Xiao).
Trends in Parasitology, January 2022, Vol. 38, No. 1 © 2021 Elsevier Ltd. All rights reserved. https://doi.org/10.1016/j.pt.2021.08.003 95
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Acknowledgments
Supported by the Guangdong Major Project of Basic and Applied Basic Research (2020B0301030007) and the Natural Science
Fund of Heilongjiang Province for Excellent Young Scholars (YQ2020C010).
Declaration of interests
The authors declare no competing interests.
Resources
www.cdc.gov/dpdx/microsporidiosis
https://clinicalinfo.hiv.gov/en/guidelines/adult-and-adolescent-opportunistic-infection/microsporidiosis
https://microsporidiadb.org/micro/app
Literature
1. Han, B. et al. (2021) Microsporidiosis in humans. Clin. Microbiol. Rev. e0001020
2. Zhang, Y. et al. (2021) Enterocytozoon bieneusi of animals-with an 'Australian twist'. Adv. Parasitol. 111, 1–73
3. Santin, M. and Fayer, R. (2011) Microsporidiosis: Enterocytozoon bieneusi in domesticated and wild animals. Res. Vet.
Sci. 90, 363–371
4. Akiyoshi, D.E. et al. (2009) Genomic survey of the non-cultivatable opportunistic human pathogen, Enterocytozoon
bieneusi. PLoS Pathog. 5, e1000261
5. Vavra, J. and Lukes, J. (2013) Microsporidia and 'the art of living together'. Adv. Parasitol. 82, 253–319
6. Han, Y. et al. (2020) Innate and adaptive immune responses against microsporidia infection in mammals. Front. Microbiol.
11, 1468
7. Li, W. et al. (2019) Host specificity of Enterocytozoon bieneusi and public health implications. Trends Parasitol. 35,
436–451
8. Li, W. and Xiao, L. (2021) Ecological and public health significance of Enterocytozoon bieneusi. One Health 12, 100209
9. Valencakova, A. and Sucik, M. (2020) Alternatives in molecular diagnostics of Encephalitozoon and Enterocytozoon
infections. J. Fungi (Basel) 6, 114
10. Han, B. and Weiss, L.M. (2018) Therapeutic targets for the treatment of microsporidiosis in humans. Expert Opin. Ther.
Targets 22, 903–915
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