High Prevalence of Enterocytozoon bieneusi in Asymptomatic Pigs and Assessment of Zoonotic Risk at the Genotype Level

Abstract

bEnterocytozoon bieneusi is an emerging and clinically significant enteric parasite infecting humans and animals and can cause life-threatening diarrhea in immunocompromised people. Pigs are considered to be one of the main reservoir hosts of E. bieneusi based on their high prevalence rates and zoonotic genotypes in pigs. As an opportunistic pathogen, E. bieneusi infection of pigs can be inapparent, which leads to neglect in detecting this parasite in pigs and assessing the epidemiological role of pigs in the transmission of human microsporidiosis. In the present study, 95 healthy pigs aged 2 or 3 months were randomly selected from three areas in Heilongjiang Province, China. E. bieneusi isolates were identified and genotyped based on the small-subunit (SSU) rRNA and internal transcribed spacer (ITS) regions of the rRNA gene by PCR and sequencing. A high prevalence of E. bieneusi was observed, 83.2% (79/95) at the SSU rRNA locus versus 89.5% (85/95) at the ITS locus. Ten ITS genotypes were obtained, comprising six known genotypes-EbpA (n ‫؍‬ 30), D (n ‫؍‬ 19), H (n ‫؍‬ 18), O (n ‫؍‬ 11), CS-1 (n ‫؍‬ 1), and LW1 (n ‫؍‬ 1)-and four novel genotypes named HLJ-I to HLJ-IV; 70.6% (60/85) of E. bieneusi genotypes were zoonotic (genotypes EbpA, D, and O). The findings of a high prevalence of E. bieneusi in pigs and a large percentage of zoonotic genotypes indicate that pigs may play a role in the transmission of E. bieneusi to humans and may become an important source of water contamination in our investigated areas.

Presence of zoonotic Cryptosporidium scrofarum, Giardia duodenalis assemblage A and Enterocytozoon bieneusi genotypes in captive Eurasian wild boars (Sus scrofa) in China: potential for zoonotic transmission

“…These studies suggest that pigs might be a source of human microsporidiosis and water pollution. Moreover, EbpC may represent the main cause of human microsporidiosis in China [21, 23–25]. Our results confirm this possibility by demonstrating the potential for the zoonotic transmission of E. bieneusi .…”

“…1), which suggests their zoonotic potential. Among them, the human-pathogenic genotype EbpC was the most prevalent, which has been frequently found in hospitalized children in Shanghai, HIV+ and HIV- people in Henan, wastewater in four cities, and pigs in multiple cities in China [1, 21, 23–25, 45, 46]. These studies suggest that pigs might be a source of human microsporidiosis and water pollution.…”

First report of Enterocytozoon bieneusi in pigs in Brazil

“…The prevalence of E. bieneusi found in this study (59.3%) was higher than those reported in other studies worldwide [18,24,26,40,56,63,66,67,[71][72][73][74], with exception of two studies, one in the Czech Republic, where 94% of 79 pigs were found E. bienesi-positive [37] and one in China, where 83.2% and 89.5% of the 95 pigs studied were positive for E. bienesi using SSU rRNA or ITS genes, respectively [65].…”

“…In one farm in the present study, 5 of 7 pigs examined were infected with this zoonotic genotype ( Table 2). This genotype was also the most prevalent in a study conducted in 95 healthy pigs in China; 79 pigs were found E. bieneusi positive with EbpA genotype identified in 30 of them [65]. This genotype is also the only genotype found in this study that has been previously reported in Brazil.…”

“…Genotype O was first reported in a pig fecal specimen in Germany [67], followed by a report in a human HIV-positive patient in Thailand five years later [31]. This genotype was later found in 8, 3, 6, and 11 fecal samples from pigs in Thailand, Germany, and China [62,65,71,72], and in 4 dogs in China [60]. Genotype EbpA, found in 7 pigs in 3 farms of this study, has been previously reported in human, pig, horse, mouse, cattle, dog, and bird samples from all continents except Australia and Antarctica (Table 1).…”