The prevalence of Cyclospora cayetanensis in water: a systematic review and meta-analysis

Filters comprised of sand and Zero Valent Iron hold promise as tools to mitigate risk posed by Cyclospora cayetanensis oocysts

Irrigation water contaminated by human fecal material may elevate the risk of produce contamination with the enteric parasite Cyclospora cayetanensis. Oocysts of C. cayetanensis are resistant to commonly used disinfectants and a method of removing C. cayetanensis from irrigation water would mitigate this risk. We evaluated zero valent iron (ZVI) sand filtration as one such method. We sought to determine if sand filters containing ZVI outperformed those without ZVI. We first evaluated the abundant poultry parasites Eimeria maxima, E. tenella and E. acervulina as surrogates for C. cayetanensis. We determined if a miniaturized gravity fed ZVI-sand filter, scaled to evaluate scarce supplies of C. cayetanensis oocysts, provided useful information about the performance of larger filtration systems. Filters were inoculated with oocysts, rinsed, and the resulting filtrate examined microscopically for oocysts. We performed experiments to measure the effect of varying ZVI concentrations, repeated filter use, simulated agricultural water, and oocyst size and condition. We then compared the performance of mini filters to that of larger, gravity-fed pool filters and found that ZVI-sand filtration was far more effective at removing Eimeria spp. from water when compared to sand filtration, at both scales. Sand mini filters retained 13-54 % of E. acervulina oocysts, and pool filters retained 82 %, but when combined with 50 % (mini filter) or 35 % (pool filter) v/v ZVI, mini filters retained 89-99 % of oocysts and pool filters retained >99 %. The effectiveness of the mini filters increased with increasing ZVI concentration, and the addition of ZVI far outweighed the influence of any other measured variable. We then performed experiments including C. cayetanensis, which provided similar results to those utilizing Eimeria; 59 % of inoculated C. cayetanensis oocysts were retained in sand mini filters, and 97 % in mini filters composed of 35 % v/v ZVI. In sum, ZVI is highly effective in removing oocysts from water and Eimeria is a useful surrogate for C. cayetanensis to assess filtration. ZVI-sand filtration shows promise as a tool to mitigate the risk of C. cayetanensis contamination of irrigation water. Further studies should evaluate the performance of ZVI-sand in pressurized fast filtration systems under a range of field conditions.

Zero-Valent Iron and Sand Filtration Reduces Levels of Cyclospora cayetanensis Surrogates, Eimeria tenella and Eimeria acervulina, in Water

Recurring outbreaks of cyclosporiasis linked to fresh produce demonstrate the need to develop interventions to reduce C. cayetanensis in irrigation water. C. cayetanensis is resistant to commonly used irrigation water treatments, such as chemical sanitizers, making removal of oocysts by filtration the most suitable intervention. This study evaluated the reduction of Eimeria tenella and E. acervulina, as surrogates for C. cayetanensis, in water using filters packed with sand alone or mixtures of sand and zero-valent iron (ZVI). Water inoculated with Eimeria spp. oocysts was filtered through laboratory-scale (PVC column) and field-scale (swimming pool filter) filters packed with either 100% sand or 50% ZVI/50% sand (v/v). Filtered and backflush water was examined microscopically for oocysts. Laboratory-scale filters with 50% ZVI significantly (p < 0.05) reduced 99.9% of E. tenella oocysts compared to 55.3% with filters containing 100% sand. At the field-scale level, 50% ZVI filters significantly (p < 0.05) reduced 70.5% of E. acervulina oocysts compared to 54.5% by 100% sand filters. Filters were backflushed to examine the recovery of these parasites during routine filter-media cleaning procedures. Backflush recovery of oocysts ranged from 4.42-16.7%. The addition of ZVI significantly improved the reduction of Eimeria spp. oocysts at both filter scales. and should be further investigated as a potential irrigation water intervention to reduce C. cayetanensis.

Detection of Cyclospora cayetanensis in Food and Water Samples: Optimized Protocols for Specific and Sensitive Molecular Methods from a Regulatory Agency Perspective

Cyclospora cayetanensis is a coccidian parasite of the phylum Apicomplexa that causes cyclosporiasis, a human-specific gastrointestinal disease. Unlike most enteric pathogens, C. cayetanensis does not infect via direct fecal-oral transmission between humans because shed oocysts must be exposed to environmental triggers prior to becoming infectious. The development of specific and sensitive detection methods for C. cayetanensis is crucial to effectively address data gaps and provide regulatory support during outbreak investigations. In this study, new more specific molecular markers for the detection of C. cayetanensis were developed based on updated genomic databases of Apicomplexa mitochondrial sequences. Novel alternative reagents and supplies, as well as optimization protocols, were tested in spiked produce and agricultural water samples. The selected Mit1C primers and probe combined showed at least 13 mismatches to other related species. The new optimized qualitative real-time PCR assay with modifications to sample processing and replacement of discontinued items produced results comparable to the previously validated methods. In conclusion, the new optimized qualitative Mit1C real-time PCR assay demonstrated an increase in its specificity in comparison to other detection methods previously published, while it showed to be robust and as sensitive as the previously validated method at the FDA. This study has also expanded the array of PCR reagents that can be used to detect C. cayetanensis in produce and agricultural water samples and provided several improvements to the method for detection in agricultural water including replacements for discontinued items and a new dialysis filter for water filtration.

The first Cyclospora cayetanensis lineage A genome from an isolate from Mexico

BACKGROUND

Cyclospora cayetanensis is a protozoan parasite that causes intestinal illness in humans worldwide. Despite its global distribution, most genomic data for C. cayetanensis has been obtained from isolates collected in the United States, leaving genetic variability among globally distributed isolates underexplored.

RESULTS

In the present study, the genome of an isolate of C. cayetanensis obtained from a child with diarrhea living in Mexico was sequenced and assembled. Evaluation of the assembly using a lineage typing system recently developed by the Centers for Disease Control and Prevention revealed that this isolate is lineage A.

CONCLUSIONS

Given that the only other whole genome assembly available from Mexico was classified as lineage B, the data presented here represent an important step in expanding our knowledge of the diversity of C. cayetanensis isolates from Mexico at the genomic level.

Molecular detection and viability discrimination of zoonotic protozoan pathogens in oysters and seawater

The presence of foodborne protozoan pathogens including Cryptosporidium parvum, Giardia duodenalis, Toxoplasma gondii, and Cyclospora cayetanensis in commercial shellfish has been reported across diverse geographical regions. In the present study, a novel multiplex nested polymerase chain reaction (PCR) assay was validated to simultaneously detect and discriminate these four targeted parasites in oyster tissues including whole tissue homogenate, digestive gland, gills, and hemolymph, as well as seawater where shellfish grow. To differentiate viable and non-viable protozoan (oo)cysts, we further evaluated reverse transcription quantitative PCR (RT-qPCR) assays through systematic laboratory spiking experiments by spiking not only dilutions of viable parasites but also mixtures of viable and non-viable parasites in the oyster tissues and seawater. Results demonstrate that multiplex PCR can detect as few as 5-10 (oo)cysts in at least one oyster matrix, as well as in 10 L of seawater. All parasites were detected at the lowest spiking dilution (5 (oo)cysts per extract) in hemolymph, however the probability of detection varied across the difference matrices tested for each parasite. RT-qPCR further discriminated viable from non-viable (heat-inactivated) C. parvum and T. gondii in seawater and hemolymph but did not perform well in other oyster matrices. This systematic spiking study demonstrates that a molecular approach combining multiplex PCR for sensitive and affordable screening of protozoan DNA and subsequent RT-qPCR assay for viability discrimination presents an important advance for accurately determining the risk of protozoal illness in humans due to consumption of contaminated shellfish.

Characterization of microbial communities in seven wetlands with different anthropogenic burden using Next Generation Sequencing in Bogotá, Colombia

Wetlands represent key ecosystems due to their remarkable biodiversity, ecological functions and multiple ecosystem services provided. In Colombia, there are 31,702 wetlands, 13 of which are in Bogotá, capital of the country. Despite the fundamental socioecological support of these aquatic ecosystems, a tremendous loss and degradation of these ecosystems has been observed due to anthropogenic perturbations. Therefore, the aim of this study was to describe the status of seven Bogotá wetlands with variable anthropogenic interventions by measuring organoleptic, physicochemical, and microbiological parameters, using commercial kits, highly sensitive equipment, and next-generation sequencing of the 16S- and 18S-rRNA genes. Our findings describe the status of seven wetlands with different anthropogenic burden in Bogotá-Colombia where physicochemical and microbiology signals of contamination were observed. Additionally, some profiles in the composition of the microbial communities, together with certain physicochemical characteristics, may represent an insight into the environmental dynamics, where Beta Proteobacteria such as Malikia represent a potential keystone in aquatic ecosystems impacted by wastewater effluent discharges; the presence of nitrates and phosphates explain the abundance of bacteria capable of oxidizing these compounds, such as Polynucleobacter. Moreover, the presence of specific prokaryotic and eukaryotic organisms, such as Clostridium, Cryptococcus, Candida, and Naegleria, reported in one or more of the wetlands assessed here, could represent a possible pathogenic risk for human and animal health. This study performed a complete evaluation of seven Bogotá wetlands with different anthropogenic impacts for the first time, and our findings emphasize the importance of maintaining continuous monitoring of these water bodies given their remarkable ecological importance and potential spill-over of several pathogens to humans and animals.

Cyclospora cayetanensis: A Perspective (2020-2023) with Emphasis on Epidemiology and Detection Methods

Cyclospora cayetanensis infections are prevalent worldwide, and the parasite has become a major public health and food safety concern. Although important efforts have been dedicated to advance toward preventing and reducing incidences of cyclosporiasis, there are still several knowledge gaps that hamper the implementation of effective measures to prevent the contamination of produce and water with Cyclospora oocysts. Some of these data gaps can be attributed to the fact that access to oocysts is a limiting factor in C. cayetanensis research. There are no animal models or in vivo or in vitro culture systems to propagate the oocysts needed to facilitate C. cayetanensis research. Thus, researchers must rely upon limited supplies of oocysts obtained from naturally infected human patients considerably restricting what can be learnt about this parasite. Despite the limited supply of C. cayetanensis oocysts, several important advances have happened in the past 3 years. Great progress has been made in the Cyclospora field in the areas of molecular characterization of strains and species, generation of genomes, and development of novel detection methods. This comprehensive perspective summarizes research published from 2020 to 2023 and evaluates what we have learnt and identifies those aspects in which further research is needed.

Global Burden of Cyclospora cayetanensis Infection and Associated Risk Factors in People Living with HIV and/or AIDS

Cyclospora cayetanensis infections remain one of the most common protozoan opportunistic causes of gastrointestinal diseases and diarrhea among people living with HIV and/or AIDS (PLWHA). This study was conducted to provide a summary of the evidence on the global burden of C. cayetanensis infection and associated risk factors among PLWHA. Scopus, PubMed, Science Direct, and EMBASE were searched up to February 2022. All original peer-reviewed original research articles were considered, including descriptive and cross-sectional studies describing C. cayetanensis in PLWHA. Incoherence and heterogeneity between studies were quantified by I index and Cochran’s Q test. Publication and population bias were assessed with funnel plots and Egger’s asymmetry regression test. All statistical analyses were performed using StatsDirect. The pooled prevalence of C. cayetanensis infection among PLWHA was 3.89% (95% CI, 2.62–5.40). The highest prevalence found in South America was 7.87% and the lowest in Asia 2.77%. In addition, the prevalence of C. cayetanensis was higher in PLWHA compared to healthy individuals. There was a relationship between a higher C. cayetanensis prevalence in PLWHA with a CD4 cell count below 200 cells/mL and people with diarrhea. The results show that PLWHA are more vulnerable to C. cayetanensis infection and emphasizes the need to implement the screening and prophylaxis tailored to the local context. Owing to the serious and significant clinical manifestations of the parasite, an early identification of seropositivity is recommended to initiate prophylaxis between PLWHA with a CD4 count ≤200 cells/mL and PLWHA who do not receive antiviral therapy.

The prevalence of Cyclospora cayetanensis in water: a systematic review and meta-analysis

Cyclospora cayetanensis is an emerging food- and waterborne pathogen that causes cyclosporiasis, a gastrointestinal disease in humans. The parasite is endemic in tropical and subtropical regions; however, its prevalence is largely dependent on environmental factors, such as climate and rainfall patterns. The objective of this paper was to conduct a systematic review and meta-analysis to determine the prevalence of C. cayetanensis in water and to determine if geography, water source and other variables influence this prevalence. A literature search was performed using search terms relating to water and C. cayetanensis in MEDLINE®, CAB Direct, Food Science and Technology Abstracts, Agricola databases and Environmental Science Index. Observational studies published in English after 1979 were eligible. Screening, data extraction and risk-of-bias assessment were performed independently by two reviewers. A multi-level random-effects meta-analysis was completed to determine the prevalence of C. cayetanensis in water and subgroup meta-analyses were performed to explore between-study heterogeneity. The search identified 828 unique articles, and after the screening, 33 articles were included in the review. The pooled prevalence of C. cayetanensis in water was 6.90% [95% confidence interval (CI) 2.25%–13.05%, I2 = 84.38%]. Subgroup meta-analyses revealed significant differences in the prevalence between continents. Additionally, laboratory methods between studies were highly variable and these findings highlight the need for further environmental research on C. cayetanensis in water using detection methods that include PCR and sequencing to accurately identify the organism. The results of this study can be used to help assess the risk of waterborne cyclosporiasis.