The global prevalence of Cyclospora cayetanensis infection: A systematic review, meta-analysis, and meta-regression

Multi-laboratory validation of a modified real-time PCR assay (Mit1C) for the detection of Cyclospora cayetanensis in fresh produce

Cyclospora cayetanensis is a foodborne protozoan parasite that causes the human diarrheal disease cyclosporiasis. Recently, the US FDA developed a modified real-time PCR method based on a specific mitochondrial target gene (Mit1C) to detect C. cayetanensis in fresh produce. The method was validated by single laboratory validation (SLV) studies in Romaine lettuce, cilantro, and raspberries. The present study aimed to evaluate the performance of the new real-time Mit1C (Mit1C qPCR) method by comparing it with the current BAM Chapter 19b qPCR (18S qPCR) as the reference method for the detection of the protozoan parasite C. cayetanensis in fresh produce in a multi-laboratory validation (MLV) setting with the participation of 13 collaborating laboratories. Each laboratory analyzed twenty-four blind-coded Romaine lettuce DNA test samples that included: two unseeded samples, three samples seeded with five oocysts, and one sample seeded with 200 oocysts in the first round and five unseeded samples, eight samples seeded with five oocysts, and five samples seeded with 200 oocysts in the second round. The overall detection rates across laboratories for Romaine lettuce samples inoculated with 200 and 5 oocysts and un-inoculated samples were 100% (78/78), 69.23% (99/143), and 1.1% (1/91), respectively, for Mit1C qPCR, and 100% (78/78), 61.54% (88/143) and 0% (0/91), respectively, for 18S qPCR. The relative level of detection (RLOD = LOD50, Mit1C/LOD50, 18S) was 0.81 with a 95% confidence interval (0.600, 1.095), which included 1. Thus, Mit1C qPCR and 18S qPCR had statistically similar levels of detection. Mit1C qPCR was highly reproducible as the between-laboratory variance in the test results was nearly zero (0) and showed a high specificity at 98.9%. In conclusion, this study demonstrated that the new, more specific Mit1C qPCR method is an effective alternative analytical tool for detection of C. cayetanensis in fresh produce.

Detectability and Persistence of Cyclospora cayetanensis Oocysts in Artificially Contaminated Soil and Fresh Herbs Grown Under Controlled Climatic Conditions

Cyclospora oocysts are thought to be highly resistant in the environment but the climatic factors which determine the presence/persistence of Cyclospora oocysts are currently unknown. The main objective of this study was to determine the effects of temperature, water content, and soil texture on C. cayetanensis detection/persistence in artificially contaminated soil and herbs grown under controlled environmental conditions. Soil and leaves of three potted herbs (cilantro, parsley, and basil) grown in growth chambers and inoculated with C. cayetanensis oocysts were collected at 7, 14, 21, 28-31, 35-38, 42-45, 49-52, and 56 days post inoculation (dpi). Under wet watering conditions, independent of temperature, positive C. cayetanensis detection was observed at each sampling collection in both soil and herb leaves. Additionally, all three herbs were found to be positive for the parasite throughout the study duration in arid watering conditions. Conversely, short-lived persistence in soil was observed under arid conditions independent of temperature in Sandy Clay Loam soil (up to 14 dpi) and in Silt Loam soil (up to 21 dpi). Our results on the effect of desiccation on the presence and persistence of oocysts may provide useful insights for the proper cleaning and sanitizing of utensils or food contact surfaces to help control the persistence of the parasite.

Epidemiology, molecular characterization, and risk factors of Acanthamoeba spp., Blastocystis spp., and Cyclospora spp. infections in snakes in China

Snakes are widely farmed in China for medicinal purposes and as pets worldwide. Acanthamoeba spp., Blastocystis spp., and Cyclospora spp. are significant zoonotic pathogens frequently discovered in various animals, causing diseases with global public health implications. However, their prevalence and zoonotic potential in snakes remain poorly understood. In this study, 812 snake faecal samples were collected across 28 China provinces. The partial small subunit (SSU) rRNA gene was amplified using polymerase chain reaction (PCR) to assess evolutionary relationships and genetic characterization. Detection rates for Acanthamoeba spp., Blastocystis spp., and Cyclospora spp. were 6.40 %, 3.33 %, and 2.71 %, respectively. Sequencing and phylogenetic analysis revealed that Cyclospora isolates were closely related to those found in humans and cattle. Subtyping for Blastocystis species identified two zoonotic subtypes (ST4, ST6) and four host-specific subtypes (ST10, ST15, ST21, ST42). Multiple Acanthamoeba genotypes were detected, including T4, T11, and T13. Furthermore, species, age, and living conditions are key risk factors. This study provides valuable insights into these infections in snakes and underscores the need for proper hygiene and One Health measures to reduce zoonotic transmission and environmental contamination.

Investigation of Cyclospora spp. in farmed fur animals based on PCR-RFLP

Cyclospora spp., foodborne intestinal protozoa with potential zoonotic risk, are distributed across the globe. However, their presence in animals bred for fur has not been extensively studied, raising concerns about zoonotic transmission. To assess the prevalence of Cyclospora spp. in fur animals in China, we collected fresh fecal samples from 862 animals, including 352 blue foxes, 275 minks, and 235 raccoon dogs, across multiple provinces. The small subunit (SSU) rRNA gene of Cyclospora spp. was amplified using nested PCR, followed by restriction fragment length polymorphism (RFLP) analysis with the Kpn2I enzyme. We also analyzed geographic location and clinical symptoms, such as diarrhea, as potential risk factors. Our findings showed an overall infection rate of 1.3 % for Cyclospora spp. in fur animals, with 2.3 % in blue foxes, 0.4 % in minks, and 0.9 % in raccoon dogs. Geographic location was a significant infection risk factor in blue foxes (P < 0.001), while diarrhea was a risk factor in all fur animals (P < 0.05). A molecular phylogenetic analysis based on SSU rRNA sequences revealed that two isolates clustered with human-derived Cyclospora cayetanensis, while the remaining isolates grouped with previously reported cattle-derived Cyclospora spp. This study is the first to report Cyclospora spp. infections in fur animals worldwide, underscoring the potential for zoonotic transmission. These findings offer crucial insights for controlling infections in fur animals, other animals, and humans.

Molecular Identification and Survey of Cyclospora spp. in Cattle in Shanxi Province, North China

To date, more than 20 species in the genus Cyclospora have been reported. Among them, Cyclospora cayetanensis has been recognized as the causative agent of human cyclosporiasis, which is characterized by severe intestinal injury and prolonged diarrhea in patients with immune dysfunction. The presence of C. cayetanensis in cattle has been confirmed. To date, however, no surveillance data are available on the occurrence and prevalence of Cyclospora spp. in cattle in Shanxi Province, North China. In the present study, a total of 761 fecal samples collected from cattle in three representative counties (Qi, Jishan, and Shanyin) in this Province were examined for Cyclospora spp. by using a polymerase-chain-reaction-restriction-fragment-length polymorphism (PCR-RFLP) test based on the nuclear small subunit ribosomal RNA (SSU rRNA) gene. The prevalence of Cyclospora spp. in cattle was 2.1%, and region, age, sex, and breed were not identified to be risk factors. Molecular evolutionary analysis based on the SSU rRNA sequences revealed that all 12 of the isolates were relatively distant from the human pathogen C. cayetanensis; seven isolates were grouped with Cyclospora colobi, whereas the others were grouped with cattle Cyclospora spp. reported previously. Though C. cayetanensis was not detected in cattle in the present study, more investigations should be performed in human populations, other animal species, or cattle from other regions of Shanxi Province and other environmental sources from the One Health perspective.

Evaluation of the Increased Genetic Resolution and Utility for Source Tracking of a Recently Developed Method for Genotyping Cyclospora cayetanensis

Cyclospora cayetanensis is a foodborne parasite that causes cyclosporiasis, an enteric illness in humans. Genotyping methods are used to genetically discriminate between specimens from cyclosporiasis cases and can complement source attribution investigations if the method is sufficiently sensitive for application to food items. A very sensitive targeted amplicon sequencing (TAS) assay for genotyping C. cayetanensis encompassing 52 loci was recently designed. In this study, we analyzed 66 genetically diverse clinical specimens to assess the change in phylogenetic resolution between the TAS assay and a currently employed eight-marker scheme. Of the 52 markers, ≥50 were successfully haplotyped for all specimens, and these results were used to generate a hierarchical cluster dendrogram. Using a previously described statistical approach to dissect hierarchical trees, the 66 specimens resolved into 24 and 27 distinct genetic clusters for the TAS and an 8-loci scheme, respectively. Although the specimen composition of 15 clusters was identical, there were substantial differences between the two dendrograms, highlighting the importance of both inclusion of additional genome coverage and choice of loci to target for genotyping. To evaluate the ability to genetically link contaminated food samples with clinical specimens, C. cayetanensis was genotyped from DNA extracted from raspberries inoculated with fecal specimens. The contaminated raspberry samples were assigned to clusters with the corresponding clinical specimen, demonstrating the utility of the TAS assay for traceback efforts.