1. INTRODUCTION
Enterocytozoon bieneusi is a prevalent pathogen in humans and an
important zoonotic agent in animals worldwide (Fayer and Santin-Duran,
2014). The most common clinical symptom of E. bieneusi infections
is diarrhea for patients with Acquired Immunodeficiency Syndrome (AIDS)
or other immunocompromising conditions while asymptomatic infections are
common for healthy persons (Matos et al., 2012). Mostly, human acquire
infections by ingesting the infectious spores of E. bieneusiwhich potential sources include: water, soil, environmental surfaces,
fecal contamination, and improper manure or irrigation water practices
in growing fruits and vegetables (Zhao et al., 2014; Li et al., 2012; Li
et al., 2019; Santin and Fayer 2011). Thus, understanding the source and
mechanism of transmission of E. bieneusi could prevent its spread
in humans.
Previous studies detected E. bieneusi using PCR-based assays with
appropriate gene markers (Santin and Fayer 2009). More than 500
genotypes, of which 142 infected humans and 49 infected both humans and
animals, were identified through the internal transcribed spacer (ITS)
sequence analysis of rDNA of the E. bieneusi (Zhou et al., 2020;
Li et al., 2019; Zhao et al., 2020). These genotypes can be grouped into
11 genetically isolated clusters by phylogenetic analysis (Li et al.,
2019). Group 1 is the largest group containing more than 300 genotypes,
including 87.6% (132/142) human-pathogenic genotypes (Gong et al.,
2019; Li et al., 2019). Meanwhile, 85.7% (42/49) zoonotic genotypes
also belong to this group (Zhou et al., 2020; Li et al., 2019). In Group
2, up to 100 genotypes are considered to be adapted to ruminants;
however, contrary to previous reports, a broader host range was
indicated for some genotypes, such as genotypes I, J, BEB6, BEB4 and
CHN3 are also commonly found in humans, enhancing their importance for
public health (Li et al., 2019). Genotypes in Groups 3 to 11 have been
mainly reported in specific hosts or wastewater (Guo et al., 2014).
Group 1 or 2 are frequently reported in pets, non-human primates,
wildlife, and livestock (pigs, cattle, sheep, etc.) (Li et al., 2019;
Zhao et al., 2020). However, the mechanism of transmission of infection
from a specific animal to humans is unclear.
Rodents have a high rate of multiplication as well as survival rate,
which have resulted in their overpopulation. They are also the
reservoirs or carriers of several types of zoonotic pathogens, includingE. bieneusi . Until now, sixty genotypes of E. bieneusi ,
including eighteen zoonotic genotypes (C, CZ3, D, BEB6, EbpC, Nig7,
Peru6, Type IV, EbpA, PigITS7, H, S7, Peru8, S6, Peru16, J, Peru11, and
PigITS5) have been identified in rodents, confirming their role in
disease transmission (Li et al., 2020; Gui et al., 2019; Deng et al.,
2016, 2018; Qi et al., 2015; Wang et al., 2019; Yu et al., 2019; Zhao et
al., 2018; Perec-Matysiak et al., 2015; Danišová et al., 2015; Guo et
al., 2014; Roelling et al., 2015; Sak et al., 2011; Cama et al., 2007)(Table 1) .
Previous studies have reported E. bieneusi infections in eight
rodent species, including, brown rats (Rattus norvegicus ), bamboo
rats (Rhizomys sinensis ), house mice (Mus musculus ),
Bower’s white-toothed rats (Berylmys bowersi ), Edward’s
long-tailed rats (Leopoldamys edwardsi ), Chipmunks
(Eutamias asiaticus ), Chinchillas (Chinchilla lanigera ),
and red-bellied squirrels (Callosciueus erythraeus ) in China.
These studies involved five provinces with infection rates ranging from
3.6% to 35.1% (Gui et al., 2019; Deng et al., 2016, 2018; Qi et al.,
2015; Wang et al., 2019; Yu et al., 2019; Zhao et al., 2018). Hainan
Province of China where is rich in rodents and they closely contact with
humans and other animals. Meanwhile, there is high prevalence ofE. bieneusi in farmed, household, and wild animals (Zhao et al.,
2020; Zhou et al., 2019; Chen et al., 2019; Zhou et al., 2020), and was
identified in humans with diarrhea (unpublished data) in Hainan, China.
Thus, it is necessary to understand E. bieneusi epidemiology in
rodents to prevent pathogen infection in humans as well as in other
animals. This study explored the prevalence of E. bieneusi in
rodents in several areas of Hainan Province of China, to evaluate the
zoonotic potential of the isolates at the genotype level.