Occurrence and genotypic characteristics of Enterocytozoon bieneusi in pigs with diarrhea

Abstract

There is limited information available on the association between Enterocytozoon bieneusi and diseases in animals or on the characteristics of the strains involved. This study examined the occurrence of E. bieneusi in piglets with and without diarrhea to determine its involvement. Among 472 fecal samples from 472 piglets (237 with diarrhea and 235 without) up to 7 weeks of age, 67 (approximately 14%) were polymerase chain reaction (PCR) positive for E. bieneusi. Of the 237 piglets with diarrhea, 38 (approximately 16%) tested positive for E. bieneusi. Of the 235 healthy piglets, 29 (approximately 12%) tested positive for E. bieneusi. This species was detected only in the younger group of piglets with diarrhea, particularly those aged less than 1 week and between 1 and 2 weeks. This suggests that E. bieneusi is a possible cause of diarrhea in piglets. This organism, however, produced asymptomatic infections in the older piglets, as there was no significant difference in the rates of occurrence between the diarrheic and nondiarrheic older piglets (aged older than 4 weeks). The internal transcribed spacer (ITS) region of the ribosomal ribonucleic acid gene of the ten E. bieneusi-positive samples was amplified using nested PCR and subsequently sequenced. Genetic polymorphisms, which were represented by five distinct genotypes (PEbA-PEbE), were found among the E. bieneusi isolates. The five genotypes identified in this study differed from each other by two to six single-nucleotide polymorphisms. Nine isolates from four genotypes (PEbA-PEbD) were homologous to previously known types that had originally been isolated from pigs. However, one isolate from the PEbE genotype was identical to type CAF1, which was originally isolated from humans. In addition, the phylogenetic relationships determined by the neighbor-joining analysis of the ITS sequences indicated this genotype to be more distant from the other pig-specific genotypes. Thus, this isolate from pigs may be distantly related to the pig-specific genotypes and may be capable of infecting humans.

Enterocytozoon bieneusiin human and animals, focus on laboratory identification and molecular epidemiology

“…In our analysis this group is clearly subdivided in eight major clades named subgroup 1a to 1 h. Within subgroup 1a, eight genotypes were found only in HIV infected patients in Gabon, Peru and Thailand (Breton et al, 2007;Leelayoova et al, 2005;Sulaiman et al, 2003a). Eight again were isolated from animals only, domestic such as swine, cattle and cat but also wild such as beaver (Buckholt et al, 2002;Dendjel et al, 2001;Jeong et al, 2007;Mathis et al, 1999;Santin et al, 2005;Santin et al, 2006;Sulaiman et al, 2003b). More interestingly, three genotypes were found both in human and animals.…”

“…In subgroup 1e, all genotypes but two (n = 14) were isolated from animals. The animals involved were swine with ten genotypes isolated in Switzerland, Germany, Korea and Thailand and cattle with three genotypes from Germany and Korea (Breitenmoser et al, 1999;Buckholt et al, 2002;Dengjel et al, 2001;Jeong et al, 2007;Lee, 2007;Rinder et al, 2000). The two exceptions were genotypes isolated in HIV-positive human in Thailand (Leelayoova et al, 2006).…”

“…Finally only one genotype named O was found both in HIV-positive patients in Thailand and in swine in Germany (Dengjel et al, 2001;leelayoova et al, 2006). The subgroup 1f, 1g and 1h contained very few genotypes, 2, 1 and 1 respectively, isolated from very few studies (Breitenmoser et al, 1999;Breton et al, 2007;Cama et al, 2007;Dengjel et al, 2001;Espern et al, 2007;Jeong et al, 2007;Liguory et al, 2001;Liguory et al, 1998). Nevertheless subgroup 1h appear to be of a particular interest since genotype Peru 16 was to date the single isolate found in the same location in human and animals, a young child and its domestic guinea pig in Peru (Cama et al, 2007).…”

“…Even in AIDS patients, the pathogenicity of E. bieneusi was questioned since some authors have not found any association between intensity of microsporidia infection and clinical symptoms (Clarridge et al, 1996;Rabeneck et al, 1993). It is now clear that the parasite is most often symptomatic in the youngest individuals, human or animals, and in AIDS patients with a very low CD4 level (Gumbo et al, 1999;Jeong et al, 2007). In the light of actual knowledge, it seems that concerning AIDS patients, the clinical situation is linked with the genotypes of the E. bieneusi "subspecies" involved.…”

Identification and Genotyping of Enterocytozoon bieneusi in China

“…Enterocytozoon bieneusi, the most frequently diagnosed microsporidial species in humans, was first reported in an AIDS patient in 1985 (4). Over the last 2 decades, E. bieneusi has been detected in humans, other mammals, and birds in more than 30 countries (1,6,10,12). However, the prevalence of this parasite in China has been unclear.…”