Detection and molecular characterization of Cryptosporidium species and Giardia assemblages in two watersheds in the metropolitan region of São Paulo, Brazil

Fresh Leafy Vegetables and Parasitic Contamination: Practical Solutions

This study aimed at investigating the parasitic contamination of fresh leafy vegetables in Tehran, Iran, during 2020-2021. A cross-sectional study was conducted and 180 fresh leafy vegetables (including leek, watercress, mint, spring onion, radish, basil, parsley, lettuce, and spinach) were collected randomly in the five regions of Tehran, Iran. Each 200-g sample was soaked with tap water containing detergent, and the obtained sediment was centrifuged and examined for parasitic stages using a light microscope. The overall rate of parasitic contamination was 19.4%, with Trichostrongylus and Toxocara eggs being the most prevalent parasites (3.9%) and the highest rate of parasitic contamination was observed in spinach (40%), whereas no contamination was found in spring onions. Except for radish, other vegetable samples had multiple parasitic infections. Due to the contamination of vegetables, it is necessary to have a suitable method to reduce the parasites. Consequently, policymakers should safeguard public health by consistently monitoring contaminants in food and prioritizing education and research on methods to mitigate their presence in the food chain.

Safe drinking water: to what extent are shallow wells reliable?

Our study investigated the presence of Cryptosporidium hominis-parvum-meleagridis and Giardia duodenalis in shallow wells used for drinking water (DW) in a rural area. Also, bovine feces were collected from their vicinity. Our findings highlight significant potential risks associated with these pathogens in DW sources. Due to the COVID-19 pandemic, samples were collected in two phases: September/2019 to March/2020 and October/2021 to April/2022. Water samples (n = 69) and feces (n = 13) were collected biweekly and analyzed using the USEPA 1623.1 method and molecular tools for species identification, and feces by direct DNA extraction. During the first phase, oocysts and cysts were detected at frequencies ranging from 9.1 to 41.7 and 27.3 to 83.3, respectively. In the second phase, oocyst frequencies ranged from not detected to 25%, while cyst ranged from 18.2 to 83.3%. Escherichia coli concentrations were significant at all collection points. C. hominis-parvum-meleagridis and G. duodenalis were notably detected in bovine feces. Our study revealed the presence of anthropogenic parasites and E. coli in DW sources intended for human consumption. These findings underscore the urgent need for preventive measures to ensure safe DW and prevent future contamination. Effective water quality surveillance is crucial in this regard.

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

Among the major issues linked with producing safe water for consumption is the presence of the parasitic protozoa Cryptosporidium spp. and Giardia spp. Since they are both responsible for gastrointestinal illnesses that can be waterborne, their monitoring is crucial, especially in water sources feeding treatment plants. Although their discovery was made in the early 1900s and even before, it was only in 1999 that the U.S. Environmental Protection Agency (EPA) published a standardized protocol for the detection of these parasites, modified and named today the U.S. EPA 1623.1 Method. It involves the flow-through filtration of a large volume of the water of interest, the elution of the biological material retained on the filter, the purification of the (oo)cysts, and the detection by immunofluorescence of the target parasites. Since the 1990s, several molecular-biology-based techniques were also developed to detect Cryptosporidium and Giardia cells from environmental or clinical samples. The application of U.S. EPA 1623.1 as well as numerous biomolecular methods are reviewed in this article, and their advantages and disadvantages are discussed guiding the readers, such as graduate students, researchers, drinking water managers, epidemiologists, and public health specialists, through the ever-expanding number of techniques available in the literature for the detection of Cryptosporidium spp. and Giardia spp. in water.

Wastewater treatment performance in microbiological removal and (oo)cyst viability assessed comparatively to fluorescence decay

Municipal wastewater is a source of pathogenic protozoan (oo)cysts and may play a significant role in spreading waterborne diseases. This scenario becomes more critical as treated sewage from municipal wastewater treatment plants (WWTP) is discharged into springs, which are often used for water supply, irrigation, recreation and, further downstream, indirect potable reuse, quite common in Brazil. This study aimed to elucidate, regarding microbiological quality, the performance of a full-scale WWTP, consisting of preliminary treatment, upflow anaerobic sludge blanket (UASB) reactor, activated sludge system and ultraviolet (UV) radiation disinfection. Pathogenic protozoa (Giardia spp. cysts and Cryptosporidium spp. oocysts), as well as microbiological indicators (Escherichia coli and Clostridium perfringens), were evaluated in terms of their removal. In addition, (oo)cyst viability and fluorescence reduction were assessed. By using the data obtained from this research, the prevalence of infection estimated for the population served by the WWTP was between 7.4% and 14.8% for giardiasis, and between 0.055% and 0.11% for cryptosporidiosis.

Parasitological, microbiological, and antimicrobial resistance profiles of raw and drinking water in a tourist city in the tri-border region of South America

Despite the large amounts of freshwater available in Brazil, the deterioration of surface water can represent a risk of waterborne disease for national and international tourists. The main goal of this study was to assess the quality of drinking water in the triple border region of Brazil before and after being treated in water treatment plants (WTPs) and in Municipal Early Childhood Education Centers (MECECs), in terms of parasitological, microbiological, and physical-chemical aspects. Different water samples were monitored: raw water (RW), treated water (TW), and tap water from the MECECs, giving 60 samples in total, to investigate the presence of Giardia and Cryptosporidium, microbiological indicators, Pseudomonas aeruginosa, and antimicrobial resistance profiles using conventional microbiological assays and parasitological, immunological, and molecular techniques. The results obtained were compared with the reference values recommended by the legislation of drinking water in Brazil. For the first time, contamination by Cryptosporidium and Giardia was demonstrated in RW used to supply WTPs, in TW of Foz do Iguaçu, and in water destined for consumption by children. A total of 52 bacterial isolates were obtained, with high percentages of multidrug resistance to antibiotics, including a carbapenem-resistant profile, highlighting the need to improve quality control standards.

Giardia spp. cysts and Cryptosporidium spp. oocysts in drinking water treatment residues: comparison of recovery methods for quantity assessment

Water treatment plant (WTP) residues, e.g. sludge and filter backwash water (FBW), may contain pathogenic microorganisms, as Giardia spp. and Cryptosporidium spp. However, recovering protozoa from such matrices lacks a formal and precise protocol, which is imperative to improve research in their detection, removal and inactivation. The latter includes a deeper challenge as some recovery methods may compromise viability. This study applied different recovery methods for G. muris cysts and C. parvum oocysts spiked into settled sludge and FBW obtained from a bench treatment. Procedures in sludge involved direct centrifugation, alkaline and acid flocculation, including purification by immunomagnetic separation (IMS). FBW samples were tested for membrane filtration (MF) and heated Tween^® scrapings followed or not by IMS. Propidium iodide (PI) inclusion was used for oocyst viability evaluation prior and after recovery. Results with purified suspensions lead to higher recovery efficiencies (RE) for C. parvum, which was assumed to relate to poor G. muris fluorescence. Analytical quality assessments were carried out with ColorSeed^® for the methods that stood out for each matrix and the results indicated lower RE than when organisms from purified suspensions were recovered. Ferric sulphate flocculation and MF, both followed by IMS reached 32.25% and 11.00% RE for Giardia spp. and 19.61% and 2.00% for Cryptosporidium spp., respectively. All of the tested methods affected oocyst viability. These results encourage further research to overcome the matrices complexity explained in this paper and increase RE, taking effects in protozoa viability into consideration.

Multilocus Genotyping of Giardia duodenalis in Mostly Asymptomatic Indigenous People from the Tapirapé Tribe, Brazilian Amazon

Little information is available on the occurrence and genetic variability of the diarrhoea-causing enteric protozoan parasite Giardia duodenalis in indigenous communities in Brazil. This cross-sectional epidemiological survey describes the frequency, genotypes, and risk associations for this pathogen in Tapirapé people (Brazilian Amazon) at four sampling campaigns during 2008–2009. Microscopy was used as a screening test, and molecular (PCR and Sanger sequencing) assays targeting the small subunit ribosomal RNA, the glutamate dehydrogenase, the beta-giardin, and the triosephosphate isomerase genes as confirmatory/genotyping methods. Associations between G. duodenalis and sociodemographic and clinical variables were investigated using Chi-squared test and univariable/multivariable logistic regression models. Overall, 574 individuals belonging to six tribes participated in the study, with G. duodenalis prevalence rates varying from 13.5–21.7%. The infection was positively linked to younger age and tribe. Infected children <15 years old reported more frequent gastrointestinal symptoms compared to adults. Assemblage B accounted for three out of four G. duodenalis infections and showed a high genetic diversity. No association between assemblage and age or occurrence of diarrhoea was demonstrated. These data indicate that the most likely source of infection was anthropic and that different pathways (e.g., drinking water) may be involved in the transmission of the parasite.

Cryptosporidium spp. and Giardia spp. (oo)cysts as target-organisms in sanitation and environmental monitoring: A review in microscopy-based viability assays

Cysts and (oo)cysts are the infective forms of parasitic protozoa, as Giardia and Cryptosporidium, which are widespread and associated to worldwide waterborne diseases outbreaks. These microorganisms pose a challenge to public health, as they are resistant to conventional disinfection methods, which make them important parameters when evaluating inactivation efficiency. However, when (oo)cysts are targets, it is challenging to infer inactivation efficacy, as it may require infectivity tests that are not often an option for laboratory routine analysis. In this scene, (oo)cyst viability based on induced excystation, membrane integrity and enzyme activity evaluated by dye inclusion and/or exclusion, as well as fluorescence reduction consist on microscopy-based techniques that may be options to estimate inactivation in the environmental context. This scoping review presents applications, advantages and limitations of these methodologies for viability assessment, in order to shed light on the (oo)cyst viability topic and provide insight strategies for choosing protocols in the environmental and sanitation field, in laboratory applications and novel research.

Epidemiology of Giardia duodenalis assemblages in Brazil: there is still a long way to go

Giardia duodenalis infection is distributed worldwide and can achieve prevalence around 60%, especially in developing countries. This protozoan is divided into eight assemblages, in which A and B have high zoonotic potential, whereas C to H are host-specific. This scenario is changing as molecular studies progress, highlighting that knowledge on host-specificity still has a long way to go. Understanding the players involved in transmission routes enables rational designs of control strategies. Considering the high prevalence of giardiasis, this review aims to gather together the data on available studies on the distribution of G. duodenalis assemblages in Brazil until September 2020.

Detection of Intestinal Parasites and Genetic Characterization of Enterocytozoon bieneusi in Hedgehogs from China

Microsporidia are a group of unicellular and opportunistic intestinal parasites in which Enterocytozoon bieneusi is a frequent species causing microsporidial infections in humans. Many domesticated and wild animals have been shown to be hosts of E. bieneusi and other microsporidia. The role of hedgehogs in the ecology of microsporidia is unclear; therefore, we investigated the prevalence and genetic diversity of E. bieneusi, Cryptosporidium, and Blastocystis spp. in hedgehogs (Erinaceus amurensis) collected from Hubei Province in Central China. PCR amplification of the internal transcribed spacer region of the ribosomal DNA indicated that 9.8% (4/41) hedgehogs were positive to E. bieneusi, but none (0/41) was positive to Cryptosporidium and Blastocystis spp. Phylogenetic analysis showed the strains detected from the hedgehogs belong to four novel genotypes (EA1-EA4), which were most closely related to type IV of group 1c. This study demonstrated that hedgehogs are hosts of E. bieneusi and may play a role in the transmission of E. bieneusi to humans in the process of being caught and slaughtered.

Detection of human intestinal protozoan parasites in vegetables and fruits: a review

Diarrheal diseases caused by intestinal protozoan parasites are a major food-borne public health problem across the world. Vegetables and fruits provide important nutrients and minerals, but are also common sources of some food-borne human pathogenic microorganisms. The contamination of raw vegetables and fruits with human pathogenic parasites are now a global public health threat, despite the health benefits of these foods in non-pharmacological prophylaxes against diseases. A large number of reports have documented the contamination of vegetables or fruits with human pathogenic microorganisms. In this paper, we reviewed the contamination and detection methods of human pathogenic intestinal protozoans that are frequently recovered from raw vegetables and fruits. The protozoan parasites include Cryptosporidium spp., Giardia duodenalis, Cyclospora cayetanensis, Entamoeba spp., Toxoplasma gondii, Balantioides coli, Blastocystis sp., Cystoisospora belli and Enterocytozoon bieneusi. The risk factors involved in the contamination of vegetables and fruits with parasites are also assessed.

New insights into the detection and molecular characterization of Cryptosporidium with emphasis in Brazilian studies: a review

Cryptosporidium spp. is a pathogenic protozoan present in the gastrointestinal tract of several hosts. This protozoan was originally classified as within the Coccidia Class and has recently been reclassified to gregarine based on studies that observed the evolutionary phases from the process of excision and sequencing of the 18S rRNA gene. Molecular biology techniques have become diagnostic tools and have also been used to understand the epidemiology of Cryptosporidium spp., since several species of this genus are very similar morphologically and morphometrically. Molecular techniques have been used in the identification of parasites, at the species and subtypes levels and to study disease transmission. The laboratory diagnosis of human cryptosporidiosis can be made by parasite detection methods, such as optical microscopy, antigens or genetic material detection, as well as serum antibodies raised to Cryptosporidium spp. Molecular methods were developed and allowed, not only an extensive revision of the taxonomy, but also an improvement in the laboratory diagnosis. In Brazil, there are few reports of Cryptosporidium spp. outbreaks in humans and all of them took place in nurseries. A few epidemiological studies developed in Brazil have used molecular methods for the detection of Cryptosporidium spp., as well as genotyping studies of their species and subtypes. The use of real-time PCR, together with microscopy and immunochromatography techniques, would result in a more precise diagnosis of cryptosporidiosis. The analysis of genotypes, subtypes and clonality of Cryptosporidium could be useful to understand and define the prognosis and severity of infections.