Researchers in southern China have reported the first molecular detection and genetic characterization of two enteric unicellular microorganisms—Enterocytozoon bieneusi and Blastocystis—in farmed chukar partridges (Alectoris chukar), a finding that adds a new bird species to the growing list of potential reservoir hosts for pathogens of public health concern. The study, published in Acta Parasitologica, surveyed 411 fecal samples from farmed chukar partridges and revealed low but notable prevalence of both organisms, including a novel genotype never before described in any host.

Enterocytozoon bieneusi is a microsporidian fungus and one of the most common causes of microsporidiosis in humans, particularly in immunocompromised individuals such as those living with HIV/AIDS, transplant recipients, and patients undergoing chemotherapy. The parasite infects the epithelial cells of the small intestine, where it replicates and produces environmentally resistant spores that are shed in feces, facilitating fecal–oral transmission through contaminated water, food, or direct contact with infected animals. Blastocystis, by contrast, is an anaerobic stramenopile—neither a classic protozoan nor a fungus—found in the gastrointestinal tracts of humans and a remarkably wide array of animals worldwide. Although its clinical significance remains debated, Blastocystis has been associated with gastrointestinal disorders such as irritable bowel syndrome and diarrhea, and certain subtypes are considered potentially pathogenic.

Chukar partridges are game birds native to Eurasia that have become increasingly important in China’s specialty poultry industry. Farmed for meat, eggs, and hunting stock, these birds are raised in intensive operations where high stocking densities, shared water sources, and accumulated manure can create conditions favorable for the transmission of enteric pathogens. Despite the economic and zoonotic relevance of this industry, molecular epidemiological data on E. bieneusi and Blastocystis in chukar partridges had been essentially nonexistent prior to this investigation.

To fill this gap, the research team, led by Yongli Jian, Houqiang Luo, and Wei Zhao, with colleagues from Wenzhou Vocational College of Science and Technology, Wenzhou Yongzheng Agricultural Development Co., Ltd., and Wenzhou Medical University, collected a total of 411 fecal samples from farmed chukar partridges in southern China. The samples were stratified by age to allow age-specific prevalence estimates. DNA was extracted from the fecal material, and species-specific target genes were amplified by polymerase chain reaction (PCR). For E. bieneusi, the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene—the standard barcode for genotype classification in this species—was targeted. For Blastocystis, the small subunit ribosomal RNA (SSU rRNA) gene was amplified, following the widely adopted DNA barcoding approach that allows assignment of isolates to subtypes (ST1 through ST10 and beyond).

The results showed an overall prevalence of 1.22% (5 of 411 birds) for E. bieneusi and 1.70% (7 of 411 birds) for Blastocystis. Age-stratified analysis revealed interesting patterns: the highest E. bieneusi prevalence occurred in yearling partridges, at 1.72% (2 of 116), while young partridges showed the highest Blastocystis infection rate, at 2.35% (2 of 85). Although these prevalences are relatively low compared with those reported in some other poultry and livestock species, the detection itself is significant, as it represents the first confirmation of these organisms in this host species anywhere in the world.

Sequence analysis of the PCR amplicons yielded genetically meaningful results. Among the E. bieneusi–positive samples, three distinct ITS genotypes were identified: two previously known genotypes, designated CM7 and BEB6, and one novel genotype, which the researchers named WZP-1. The known genotypes carry particular weight in the zoonotic risk assessment. BEB6 is a so-called Group 1 genotype with a broad host range, having been reported in cattle, deer, and various birds, and it is considered to have zoonotic potential. CM7 has also been documented in birds and other hosts. The identification of the novel genotype WZP-1 demonstrates that chukar partridges may harbor genetic variants of the parasite not previously captured in global surveillance efforts, underscoring how much unknown diversity remains even in intensively managed farmed animals.

For Blastocystis, sequence analysis of the SSU rRNA gene identified two subtypes, ST6 and ST7. Both subtypes are regarded as zoonotic and have been detected in human patients as well as in poultry and wild birds. ST6 and ST7 are among the subtypes most frequently recovered from avian hosts, and their presence in farmed partridges is consistent with the pattern seen in chickens, ducks, and turkeys surveyed in China, Lebanon, and elsewhere. The fact that every genotype and subtype identified in this study has documented zoonotic potential is the central public health message of the work: farmed chukar partridges may act as reservoir hosts from which humans could acquire these enteric pathogens through direct contact, occupational exposure, or contamination of the environment and food chain.

The zoonotic implications extend beyond the farm gate. Previous studies have shown that microsporidian spores are capable of contaminating fresh vegetables and fruits, surface waters, and urban environments. Spores of human-virulent E. bieneusi genotypes have been detected in the fecal droppings of urban pigeons in Amsterdam, in captive wildlife, in pet birds across several countries, and on the surfaces of produce in Henan, China. Blastocystis subtypes with human affinity have similarly been documented in dairy cattle, rodents, raptors, and nonhuman primates. In this context, manure from partridge farms represents a potential environmental reservoir, and the authors specifically recommend basic hygiene practices and appropriate manure management on chukar partridge farms to reduce the risk of environmental contamination and zoonotic transmission.

The technical pipeline used in the study reflects the current gold standard for molecular epidemiology of these organisms. Rather than relying on microscopy—which cannot distinguish morphologically identical genotypes of E. bieneusi or subtypes of Blastocystis—the researchers used PCR amplification of species-specific genetic markers followed by sequencing and phylogenetic analysis. Genotype and subtype assignments were made by comparing the obtained sequences with reference sequences in public databases, and maximum likelihood (ML) methods were employed for phylogenetic reconstruction. The representative nucleotide sequences generated in the study have been deposited in the GenBank database under accession numbers PX563286 through PX563290 for E. bieneusi and PX419260 through PX419266 for Blastocystis, making the data freely available to the research community for future comparative analyses.

The finding of a novel E. bieneusi genotype is particularly noteworthy from an evolutionary standpoint. The ITS locus, while highly informative for typing, represents only a small portion of the parasite genome, and multilocus sequence typing studies have revealed considerable hidden diversity within single ITS genotypes. The discovery of WZP-1 in a novel avian host raises questions about the population structure and host specificity of E. bieneusi in birds, and whether partridge-adapted lineages circulate independently or mix with genotypes circulating in other poultry and wild birds on the same farms. Similarly, the co-occurrence of two Blastocystis subtypes in a single host species suggests that multiple transmission routes—possibly involving environmental contamination, feed, or interspecies contact—may operate within partridge farming systems.

Age-related patterns in prevalence, though subtle given the small number of positive samples, hint at potential differences in exposure or susceptibility across life stages. Younger birds showed the highest Blastocystis rates, which could reflect immature gut microbiota or increased susceptibility during early development, whereas yearlings carried the highest E. bieneusi burden. Larger sample sizes and longitudinal sampling would be needed to determine whether these patterns are robust and to identify risk factors such as stocking density, feed sources, or biosecurity measures.

From a broader perspective, the study contributes baseline molecular epidemiological data for two pathogens in a host species that had been essentially unstudied. China’s specialty poultry sector—including pigeons, quails, and partridges—has expanded rapidly in recent decades, and the gastrointestinal parasitic fauna of many of these species remains poorly characterized. Studies of related birds, such as red-legged partridges hunted in Spain, have similarly highlighted the importance of monitoring gastrointestinal parasites in game birds, both for animal welfare and for public health. The current work extends this surveillance framework to chukar partridges and demonstrates that even low-prevalence infections can be of consequence when the genotypes involved are known human pathogens.

The research was approved by the Research Ethics Committee and the Animal Ethical Committee of Wenzhou Medical University, and all fecal samples were obtained with the consent of the animals’ owners or managers, with no harm to the animals. The work was supported by the Wenzhou Science and Technology Commissioner Project, the Wenzhou Basic Public Welfare Research Project, and the Technological Innovation Service Project of the Wenzhou Association for Science and Technology.

As the global burden of zoonotic enteric diseases continues to attract attention, particularly in the wake of pandemic preparedness initiatives, studies like this one illustrate the value of systematic molecular surveillance in underexamined animal reservoirs. The identification of zoonotic genotypes and subtypes of E. bieneusi and Blastocystis in farmed chukar partridges serves as a reminder that public health risk can emerge from unexpected corners of the food production system, and that vigilance—combined with practical farm-level interventions such as manure management and hygiene—remains one of the most effective tools for preventing zoonotic transmission at the human–animal–environment interface.

Subject of Research: Prevalence and genetic diversity of Enterocytozoon bieneusi and Blastocystis in farmed chukar partridges (Alectoris chukar) in southern China, with assessment of zoonotic potential

Subject of Research: Biology

Article Title: First Molecular Detection and Genotypic Characterization of Enterocytozoon bieneusi and Blastocystis in Farmed Chukar Partridges (Alectoris chukar) in Southern China

Article References: Jian, Y., Luo, H., Han, Q., Wang, M., Cui, X., Li, P., Xia, K., Gao, Y., Song, H., Hu, L., Liu, S., Tu, Y., & Zhao, W. (2026). First Molecular Detection and Genotypic Characterization of Enterocytozoon bieneusi and Blastocystis in Farmed Chukar Partridges (Alectoris chukar) in Southern China. Acta Parasitologica, 71(5), Article 211. https://doi.org/10.1007/s11686-026-01394-y

Image Credits: AI Generated

DOI: 10.1007/s11686-026-01394-y

Keywords: Enterocytozoon bieneusi, Blastocystis, chukar partridge, zoonotic, genotyping, ITS, SSU rRNA, prevalence, southern China, public health, farmed birds

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William Thompson. (September 11, 2026). Microsporidia and Blastocystis Found in Farmed Chukar Partridges in Southern China. Scienmag. https://scienmag.com/microsporidia-and-blastocystis-found-in-farmed-chukar-partridges-in-southern-china/

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