Abstract
BackgroundEnterocytozoon bieneusi is the most frequently detected microsporidian species in humans and animals. Currently, to the best of our knowledge, no information on E. bieneusi infection in Himalayan marmots (Marmota himalayana) and Alashan ground squirrels (Spermophilus alashanicus) is available worldwide. The aim of the present study was to understand the occurrence and genetic characterizations of E. bieneusi in Himalayan marmots and Alashan ground squirrels in the Qinghai-Tibetan Plateau area (QTPA), Gansu Province, China.MethodsA total of 498 intestinal contents were collected from 399 Himalayan marmots and 99 Alashan ground squirrels in QTPA. These samples were screened for the presence of E. bieneusi by using nested polymerase chain reaction and sequencing of the internal transcribed spacer (ITS) region of the ribosomal RNA (rRNA) gene. The ITS-positive sequences were aligned and phylogenetically analyzed to determine the genotypes of E. bieneusi.ResultsThe average infection rate of E. bieneusi was 10.0% (50/498), with 11.8% (47/399) in Himalayan marmots and 3.0% (3/99) in Alashan ground squirrels. A total of 7 distinct E. bieneusi genotypes were confirmed: 1 known genotype, YAK1 (n = 18) and 6 novel genotypes, named as ZY37 (n = 27), HN39 (n = 1), HN96 (n = 1), SN45 (n = 1), XH47 (n = 1) and ZY83 (n = 1). All the genotypes obtained in the present study were classified into group 1.ConclusionsTo our knowledge, this is the first report of E. bieneusi in Himalayan marmots and Alashan ground squirrels in China. The identification of genotype YAK1 in the two rodent species expanded the host range of this genotype. All the seven genotypes were clustered into zoonotic group 1, suggesting that these animal species can be potential epidemiological vectors of zoonotic microsporidiosis caused by E. bieneusi and pose a threat to ecological security. It is necessary to strengthen management practices and surveillance in the investigated areas to reduce the risk of E. bieneusi infection from the two rodent species to humans.
Highlights
Enterocytozoon bieneusi is the most frequently detected microsporidian species in humans and animals
Sample collection A total of 498 intestinal contents were collected from 399 Himalayan marmots and 99 Alashan ground squirrels from June to September 2017 in Qinghai-Tibetan Plateau area (QTPA) in Gansu Province, China
Occurrence of E. bieneusi A total of 498 intestinal contents of Himalayan marmots and Alashan ground squirrels were screened for the presence of E. bieneusi by amplifying the internal transcribed spacer (ITS) region with nested polymerase chain reaction (PCR)
Summary
Enterocytozoon bieneusi is the most frequently detected microsporidian species in humans and animals. To the best of our knowledge, no information on E. bieneusi infection in Himalayan marmots (Marmota himalayana) and Alashan ground squirrels (Spermophilus alashanicus) is available worldwide. Enterocytozoon bieneusi is the most frequently detected species (more than 90%) in microsporidiosis cases [3]. In 2009, a food-borne microsporidiosis outbreak caused by E. bieneusi was reported in Sweden [7]. No water-borne microsporidiosis outbreak has been reported to date; E. bieneusi spores have been found in multiple water bodies, for example drinking-source watersheds [9], recreational watersheds [10], and wastewater resources used for irrigation of farmlands [11], indicating the possibility of waterborne transmission
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