Cyclosporiasis can cause prolonged watery diarrhea and other gastrointestinal symptoms, while outbreaks are frequently associated with contaminated fresh produce or water. Although C. cayetanensis is generally regarded as human-specific, polymerase chain reaction (PCR) surveys have reported the parasite in cattle, monkeys, pets, fur-bearing animals, snakes, and wildlife. Many tests target the small-subunit ribosomal RNA (SSU rRNA), a region in which Cyclospora and Eimeria can be highly similar. Cross-reacting primers, unsuitable reference sequences, and incomplete phylogenetic comparisons may therefore misidentify a related parasite into an apparent zoonotic threat and distort public-health priorities. Because of these challenges, deeper investigation of Cyclospora host specificity and its true transmission routes is needed.
Published (DOI: 10.1186/s44280-025-00094-y) on October 21, 2025, in One Health Advances, the review was conducted by researchers from the College of Veterinary Medicine at South China Agricultural University. The team examined Cyclospora epidemiology and genetic diversity in China, reassessed reports from animal and environmental samples, and evaluated whether existing molecular evidence supports zoonotic transmission of C. cayetanensis across different host species.
The researchers searched PubMed and the China National Knowledge Infrastructure (CNKI), without language restrictions, for studies published through 2025. They compiled prevalence findings from human populations and reviewed reports involving nonhuman primates, cattle, companion animals, fur animals, snakes, fresh produce, sewage, and water. Published sequence data were then re-evaluated, with particular attention to SSU rRNA identity, reference-sequence validity, and phylogenetic placement.
Across PCR-based human studies, C. cayetanensis was detected in 111 of 13,703 people, an overall prevalence of 0.8%, although individual estimates ranged from 0.2% to 10.0%. Infection patterns varied with residence, season, and clinical or immune status, while many cases occurred during warmer months. Multilocus sequence typing (MLST), whole-genome sequencing (WGS), and mitochondrial analyses indicated that Chinese isolates form geographically distinctive populations.
Animal evidence was less convincing. Macaques were mainly infected with the host-adapted species Cyclospora macacae. Reanalysis of published data suggested that a "Cyclospora-like"parasite reported in cattle was probably Eimeria subspherica, while several sequences attributed to C. cayetanensis in cattle, fur animals, Mongolian gazelles, and snakes clustered more closely with known Eimeria species. Limited detections of C. cayetanensis in lettuce, sewage, wastewater, and macaque-associated lake water nevertheless reinforce the need to monitor environmental routes, particularly irrigation water that may contaminate crops.
The authors said the central message is not that animal or environmental surveillance should be reduced, but that unexpected detections require stronger and more transparent evidence. They said a single PCR result or close SSU rRNA match cannot reliably establish a new host when related Eimeria species may be present. Microscopy, validated reference sequences, and confirmation across multiple genetic markers can distinguish genuine transmission signals from analytical error. This distinction matters because overstating zoonotic risk may misdirect public-health resources, while underestimating contaminated produce or water could leave important exposure routes insufficiently controlled.
The review provides a diagnostic roadmap for laboratories, veterinarians, food-safety agencies, and outbreak investigators. Suspected Cyclospora infections in unexpected hosts should be verified by microscopy, including examination of oocyst size, shape, and sporulation, rather than by PCR alone. Sequence analysis should include validated references from both Cyclospora and Eimeria and should be followed by multilocus confirmation. The authors also recommend combining SSU rRNA analysis with markers such as the cytochrome c oxidase subunit I (COI) gene. More accurate identification could improve outbreak source attribution, strengthen surveillance of irrigation water and fresh produce, distinguish true hosts from mechanical carriers, and support targeted cyclosporiasis prevention without exaggerating evidence for cross-species transmission.
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References
DOI
10.1186/s44280-025-00094-y
Original Source URL
https://doi.org/10.1186/s44280-025-00094-y
Funding information
National Key Research and Development Program of China (2023YFD1801000)；Guangdong Basic and Applied Basic Research Foundation (2023A1515012862)；Specific University Discipline Construction Project (2023B10564003)；and the 111 Center (D20008).
About One Health Advances
One Health Advances is a peer-reviewed, open access journal committed to publish high-quality research articles, comments, correspondence and reviews describing the advances in public health. The topics primarily focus on antimicrobial resistance, animal-derived food safety, and animal diseases with a preference for zoonoses. Prof. Jianzhong Shen (China Agricultural University, China) and Prof. Stefan Schwarz (Freie Universität Berlin, Germany) serve as the Editors-in-Chief.