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We describe a multiannual outbreak of keratoconjunctivitis caused by the microsporidium Vittaforma corneae in the Sea of Galilee, Israel. Patients had multifocal punctate corneal infiltrates and reduced visual acuity, confirmed by locally-developed pathogen-specific real-time PCR. Topical chlorhexidine, rather than traditional antimicrobial drugs, proved an effective and safe primary treatment.

Cryptosporidium spp. and Enterocytozoon bieneusi are two well-known protist pathogens which can result in diarrhea in humans and animals. To examine the occurrence and genetic characteristics of Cryptosporidium spp. and E. bieneusi in pet red squirrels (Sciurus vulgaris), 314 fecal specimens were collected from red squirrels from four pet shops and owners in Sichuan province, China. Cryptosporidium spp. and E. bieneusi were examined by nested PCR targeting the partial small subunit rRNA (SSU rRNA) gene and the ribosomal internal transcribed spacer (ITS) gene respectively. The infection rates were 8.6% (27/314) for Cryptosporidium spp. and 19.4% (61/314) for E. bieneusi. Five Cryptosporidium species/genotypes were identified by DNA sequence analysis: Cryptosporidium rat genotype II (n = 8), Cryptosporidium ferret genotype (n = 8), Cryptosporidium chipmunk genotype III (n = 5), Cryptosporidium rat genotype I (n = 4), and Cryptosporidium parvum (n = 2). Additionally, a total of five E. bieneusi genotypes were revealed, including three known genotypes (D, SCC-2, and SCC-3) and two novel genotypes (RS01 and RS02). Phylogenetic analysis revealed that genotype D fell into group 1, whereas the remaining genotypes clustered into group 10. To our knowledge, this is the first study to report Cryptosporidium spp. and E. bieneusi in pet red squirrels in China. Moreover, C. parvum and genotype D of E. bieneusi, previously identified in humans, were also found in red squirrels, suggesting that red squirrels may give rise to cryptosporidiosis and microsporidiosis in humans through zoonotic transmissions. These results provide preliminary reference data for monitoring Cryptosporidium spp. and E. bieneusi infections in pet red squirrels and humans.

Research conducted on model organisms may be biased due to undetected pathogen infections. Recently, screening studies discovered high prevalence of the microsporidium Pseudoloma neurophilia in zebrafish ( Danio rerio ) facilities. This spore-forming unicellular parasite aggregates in brain regions associated with motor function and anxiety, and despite its high occurrence little is known about how sub-clinical infection affects behaviour. Here, we assessed how P. neurophilia infection alters the zebrafish´s response to four commonly used neurobehavioral tests, namely: mirror biting, open field, light/dark preference and social preference, used to quantify aggression, exploration, anxiety, and sociability. Although sociability and aggression remained unaltered, infected hosts exhibited reduced activity, elevated rates of freezing behaviour, and sex-specific effects on exploration. These results indicate that caution is warranted in the interpretation of zebrafish behaviour, particularly since in most cases infection status is unknown. This highlights the importance of comprehensive monitoring procedures to detect sub-clinical infections in laboratory animals.

We identified Encephalitozoon cuniculi genotype II parasites as a cause of extraintestinal microsporidiosis in 2 owners of birds also infected with E. cuniculi. Patients experienced long-lasting nonspecific symptoms; the disease course was more progressive in a patient with diabetes. Our findings suggest direct bird-to-human transmission of this pathogen.

Multiple infections are common in honey bees, Apis mellifera , but the possible role of nutrition in this regard is poorly understood. Microsporidian infections, which are promoted by protein-fed, can negatively correlate with virus infections, but the role of protein nutrition for the microsporidian-virus interface is unknown. Here, we challenged naturally deformed wing virus - B (DWV-B) infected adult honey bee workers fed with or without pollen ( = protein) in hoarding cages, with the microsporidian Nosema ceranae . Bee mortality was recorded for 14 days and N. ceranae spore loads and DWV-B titers were quantified. Amongst the groups inoculated with N. ceranae , more spores were counted in protein-fed bees. However, N. ceranae infected bees without protein-diet had reduced longevity compared to all other groups. N. ceranae infection had no effect on protein-fed bee’s longevity, whereas bees supplied only with sugar-water showed reduced survival. Our data also support that protein-feeding can have a significant negative impact on virus infections in insects. The negative correlation between N. ceranae spore loads and DWV-B titers was stronger expressed in protein-fed hosts. Proteins not only enhance survival of infected hosts, but also significantly shape the microsporidian-virus interface, probably due to increased spore production and enhanced host immunity.

Hepatopancreatic microsporidiosis (HPM) caused by Enterocytozoon hepatopenaei (EHP) is an important disease of cultivated shrimp. Heavy infections may lead to retarded growth and unprofitable harvests. Existing PCR detection methods target the EHP small subunit ribosomal RNA (SSU rRNA) gene (SSU-PCR). However, we discovered that they can give false positive test results due to cross reactivity of the SSU-PCR primers with DNA from closely related microsporidia that infect other aquatic organisms. This is problematic for investigating and monitoring EHP infection pathways. To overcome this problem, a sensitive and specific nested PCR method was developed for detection of the spore wall protein (SWP) gene of EHP (SWP-PCR). The new SWP-PCR method did not produce false positive results from closely related microsporidia. The first PCR step of the SWP-PCR method was 100 times (104 plasmid copies per reaction vial) more sensitive than that of the existing SSU-PCR method (106 copies) but sensitivity was equal for both in the nested step (10 copies). Since the hepatopancreas of cultivated shrimp is not currently known to be infected with microsporidia other than EHP, the SSU-PCR methods are still valid for analyzing hepatopancreatic samples despite the lower sensitivity than the SWP-PCR method. However, due to its greater specificity and sensitivity, we recommend that the SWP-PCR method be used to screen for EHP in feces, feed and environmental samples for potential EHP carriers.

Enterocytozoon bieneusi is a common cause of human microsporidiosis and can infect a variety of animal hosts worldwide. In Thailand, previous studies have shown that this parasite is common in domestic animals. However, information on the prevalence and genotypes of this parasite in other synanthropic wildlife, including bats, remains limited. Several pathogens have been previously detected in bats, suggesting that bats may serve as a reservoir for this parasite. In this study, a total of 105 bat guano samples were collected from six different sites throughout Thailand. Of these, 16 from Chonburi (eastern), Ratchaburi (western), and Chiang Rai (northern) provinces tested positive for E. bieneusi , representing an overall prevalence of 15.2%. Based on ITS1 sequence analysis, 12 genotypes were identified, including two known genotypes (D and type IV) frequently detected in humans and ten novel potentially zoonotic genotypes (TBAT01-TBAT10), all belonging to zoonotic group 1. Lyle’s flying fox ( Pteropus lylei ), commonly found in Southeast Asia, was identified as the host in one sample that was also positive for E. bieneusi . Network analysis of E. bieneusi sequences detected in this study and those previously reported in Thailand also revealed intraspecific divergence and recent population expansion, possibly due to adaptive evolution associated with host range expansion. Our data revealed, for the first time, multiple E. bieneusi genotypes of zoonotic significance circulating in Thai bats and demonstrated that bat guano fertilizer may be a vehicle for disease transmission.

Background Enterocytozoon bieneusi is the dominant specie of microsporidia which can infect both anthroponotic and zoonotic species. The golden snub-nosed monkey is an endangered primate which can also infect by E. bieneusi . To date, few genetic data on E. bieneusi from golden snub-nosed monkeys has been published. Therefore, to clarify the prevalence and genotypes of E. bieneusi in captive golden snub-nosed monkeys is necessary to assess the potential for zoonotic transmission. Result We examined 160 golden snub-nosed monkeys from six zoos in four cities in China, using PCR and comparative sequence analysis of the ribosomal internal transcribed spacer (ITS). The overall prevalence of E. bieneusi was 46.2% (74/160); while the prevalence was 26.7%, 69.1%, 69.4% and 33.3% in Shanghai Zoo, Shanghai Wild Animal Park, Tongling Zoo, and Taiyuan Zoo respectively ( P  = 0.006). A total of seven E. bieneusi genotypes were found that included four known (D, J, CHG1, and CHG14) and three new (CM19–CM 21) genotypes. The most common genotype was D (54/74, 73.0%), followed by J (14/74, 18.9%); other genotypes were restricted to one or two samples. Phylogenetic analysis revealed that genotype D belonged to the previously-characterized Group 1, with zoonotic potential; whereas genotypes J, CHG1, CHG14 and CM19–CM 21 clustered in the previously-characterized Group 2, the so-called cattle host specificity group. Conclusions The findings of high prevalence of zoonotic E. bieneusi genotypes D and J in golden snub-nosed monkeys suggest that golden snub-nosed monkeys may be the reservoir hosts for human microsporidiosis, and vice versa.

About the Authors: Grant D. Stentiford * E-mail: grant.stentiford@cefas.co.uk Affiliations International Centre of Excellence for Aquatic Animal Health, Centre for Environment Fisheries and Aquaculture Science, Weymouth Laboratory, Weymouth, Dorset, United Kingdom, Centre for Sustainable Aquaculture Futures, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom ORCID logo http://orcid.org/0000-0001-6597-5413 David Bass Affiliations International Centre of Excellence for Aquatic Animal Health, Centre for Environment Fisheries and Aquaculture Science, Weymouth Laboratory, Weymouth, Dorset, United Kingdom, Centre for Sustainable Aquaculture Futures, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom, Department of Life Sciences, The Natural History Museum, London, United Kingdom Bryony A. P. Williams Affiliations Centre for Sustainable Aquaculture Futures, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom, Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter, United Kingdom ORCID logo http://orcid.org/0000-0003-1123-2176 Citation: Stentiford GD, Bass D, Williams BAP (2019) Ultimate opportunists—The emergent Enterocytozoon group Microsporidia. In at least one case (Paranucleospora/Desmozoon), the parasite is known to cycle between an invertebrate (copepod crustacean) and fish (salmon) host, raising the prospect of the capacity for trophic transfer in other members of the EGM. [...]of which selection pressures led to the loss of the glycolytic pathway in the EGM, it still leaves this group with the problem of not being able to generate/acquire energy in the spore stage, meaning that they do not have immediate access to ATP for the potentially energetic process of spore germination. (Microsporidia, Enterocytozoonidae) with a life cycle in the salmon louse (Lepeophtheirus salmonis, Copepoda) and Atlantic salmon (Salmo salar).