Establishing the Performance of Next-Generation Amplicon Sequencing for Detection of Giardia duodenalis in Ready-to-Eat Packaged Leafy Greens

Giardia duodenalis is a globally distributed intestinal parasite that commonly infects both humans and animals. G. duodenalis is a species complex, which includes eight assemblages that vary both in genetic structure and host specificity. The prevalence of mixed-assemblage G. duodenalis cysts on food, an understudied infection route for G. duodenalis, remains unknown. In the present study, a method able to detect G. duodenalis mixed-assemblage infections using next-generation amplicon sequencing (NGS) of the beta-giardin gene was applied in combination with the US-FDA's BAM Chapter 19b protocol for the detection of G. duodenalis from fresh produce to ascertain the limit of detection of G. duodenalis on leafy greens. Ready-to-eat baby Romaine lettuce was inoculated with 5 (n = 5), 20 (n = 10), 100 (n = 10), 200 (n = 10), or 1,000 (n = 10) G. duodenalis cysts of the assemblage B strain H3. Detection of G. duodenalis was successful in 100% of the samples seeded with 1,000, 200, and 100 cysts, in 50% of the samples seeded with 20 cysts, and in none of the samples seeded with 5 cysts. We thus demonstrate robust detection of G. duodenalis on packaged leafy greens using the BAM Chapter 19B method coupled with assemblage-sensitive NGS. This protocol provides a new diagnostic tool useful for both prevalence studies and outbreak investigations involving fresh produce that may assist in better describing the role of G. duodenalis in foodborne illness and in protecting consumers from contaminated fresh produce.

Exploring genetic variability of Giardia duodenalis and Enterocytozoon bieneusi in raw vegetables and fruits: implications for food safety and public health in Mozambique

Giardia duodenalis and Enterocytozoon bieneusi are etiological agents of enteric diseases characterized by diarrhea that can progress to chronicity in humans, especially in children and in immunocompromised patients. This study aims to assess the genetic pattern of G. duodenalis and E. bieneusi detected in vegetables and fruits commercialized in Maputo markets, Mozambique and determine their public health importance. Eight study points were sampled: a farmer zone, a wholesale, four retail markets, and two supermarkets in Maputo city, where eight types of horticultural products were purchased. Using nested-PCR methods, 2.8% (9/321) and 1.3% (4/321) of samples monitored were positive for G. duodenalis and E. bieneusi, respectively. Based on the analysis of the β-giardin and ITS rRNA sequences of G. duodenalis and E. bieneusi detected, respectively, four different sequences of G. duodenalis (three novel sequences: BgMZ1, BgMZ2, and BgMZ3, and one known sequence) all from assemblage B and three genotypes of E. bieneusi (two novel sequences: EbMZ4 and EbMZ5, and one known sequence: KIN-1) from group 1. These microorganisms were found and characterized for the first time in horticultural products in Maputo markets. All identified G. duodenalis and E. bieneusi display high genetic similarity within their β-giardin and ITS rRNA sequences, respectively, having been clustered into assemblages and genotypes with high zoonotic transmission potential. Our study may represent a relevant step in the understanding of these intestinal pathogens in association with fresh vegetables and fruits for human consumption, for a better and broader "One Health" approach.

Occurrence of Intestinal Parasites of Public Health Significance in Fresh Horticultural Products Sold in Maputo Markets and Supermarkets, Mozambique

(1) Background: Giardia duodenalis and Cryptosporidium are important neglected parasites associated with diarrhea, such as the emerging Enterocytozoon bieneusi. All three are foodborne parasites raising concerns in public health. This study intended to understand the intestinal parasite occurrence with emphasis on G. duodenalis, Cryptosporidium, and E. bieneusi in fresh fruits/vegetables sold in the main municipal markets of Maputo city, Mozambique. (2) Methods: A total of 321 fresh horticultural products were purchased in the rainy and dry seasons (five markets/two supermarkets/one agricultural zone). Light microscopy (LM) and PCR analysis were performed. (3) Results: By LM and/or PCR, 29.3% of the samples presented at least one parasite (rainy season: 22.9%; dry season: 35.1%). The most contaminated horticultural products: collected in dry season, from Zimpeto and Fajardo markets, lettuce and pointed white cabbage. Overall, 3.7% of G. duodenalis, 1.3% of E. bieneusi, and other intestinal parasites (pathogenic and non-pathogenic) were identified. (4) Conclusions: Important pathogenic intestinal parasites were identified in fruits/vegetables commercially purchased in Maputo City. This fact must be taken into consideration when planning the management of these horticultural markets, in order to reduce the risk of contamination of fresh produce by intestinal parasites, and to prevent foodborne diseases.

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.

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 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.

Giardia: an under-reported foodborne parasite

Foodborne zoonotic pathogens are a serious public health issue and result in significant global economic losses. Despite their importance to public health, epidemiological data on foodborne diseases including giardiasis caused by the enteric parasite, Giardia duodenalis, are lacking. This parasite is estimated to cause ∼28.2 million cases of diarrhoea each year due to contamination of food, but very few foodborne outbreaks have been documented due to the limitations of current detection as well as surveillance methods. The current method for the recovery of Giardia cysts from food matrices using immunomagnetic separation requires further standardisation and cost reduction before it can be widely used. It also should incorporate downstream molecular procedures for genotyping, and traceback and viability analyses. Foodborne giardiasis can be potentially controlled through improvements in national disease surveillance systems and the establishment of Hazard Analysis and Critical Control Point interventions across the food chain. Studies are needed to assess the true prevalence and public health impact of foodborne giardiasis.