Abstract
BackgroundEnterocytozoon bieneusi is one of the commonest microsporidians contributing to human microsporidiosis, and is frequently found in animals in various countries. However, there is limited epidemiological information on this microorganism in Australia. Here, we undertook the first molecular epidemiological study of E. bieneusi in cats and dogs in Victoria.ResultsGenomic DNAs were extracted from 514 individual faecal deposits from cats (n = 172) and dogs (n = 342) and then tested using PCR-based sequencing of the internal transcribed spacer (ITS) of nuclear ribosomal DNA. Four distinct genotypes (designated D, PtEb IX, VIC_cat1 and VIC_dog1) of E. bieneusi were identified in 20 of the 514 faecal samples (3.9%). Genotype D is known to have a broad host range (humans and other animals) and has a wide geographical distribution around the world. The identification of this genotype here suggests that companion animals might represent reservoir hosts that are able to transmit E. bieneusi infection to humans in Australia. A phylogenetic analysis of ITS sequence data revealed that the novel genotype VIC_cat1 is related to the known genotype type IV within Group 1, and the new genotype VIC_dog1 is linked to a contentious “Group 3”, which includes genotypes reported previously in the published literature to represent Group 2 or 3.ConclusionsA future, large-scale phylogenetic study of all known E. bieneusi genotypes, including VIC_dog1, should aid in clarifying their relationships and assignment to Groups, and in the identification of new genotypes, thus assisting epidemiological investigations.
Highlights
Enterocytozoon bieneusi is one of the commonest microsporidians contributing to human microsporidiosis, and is frequently found in animals in various countries
We investigated the prevalence of E. bieneusi in companion animals with a relatively close association to humans in both urban and rural environments in the state of Victoria, Australia, and characterised genotypes and assessed their zoonotic potential using a molecular phylogenetic approach
There was a significant association between age and prevalence for E. bieneusi (P = 0.016), with juvenile animals having 3.11-times higher risk of E. bieneusi-positivity than adults (OR = 3.11; 95% Confidence interval (CI) [1.264–7.663]) (Table 2)
Summary
Enterocytozoon bieneusi is one of the commonest microsporidians contributing to human microsporidiosis, and is frequently found in animals in various countries. As an emerging infectious agent, E. bieneusi is the commonest species contributing to human microsporidiosis [2], characterised by symptoms of acute or chronic diarrhoea, malabsorption and/ or wasting [3]. E. bieneusi has been found in a broad host range, including humans and various orders of other animals (including mammals: Artiodactyla, Lagomorpha, Carnivora, Perissodactyla, Primates and Rodentia, and birds: Columbiformes, Falconiformes, Galliformes and Passeriformes) as well as in water and food samples [3]. Some genotypes of E. bieneusi (e.g., D and EbpC) commonly reported in humans [7] have been found in animals [8, 9]. This aspect raises the questions as to whether animals with a close affiliation with people play a significant role in the transmission of E. bieneusi infection to humans
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