Predominance of Giardia duodenalis Assemblage AII in Fresh Leafy Vegetables from a Market in Southern Brazil

Abstract

We investigated the presence of Giardia duodenalis cysts and its genotypes in raw leafy vegetables sold in a Brazilian market. These products are different from those sold in most street markets because the producers themselves display and sell their products and rely on specialized technical and sanitary assistance. Vegetable and water samples were collected from 14 (80%) producers who cultivated vegetables that are typically consumed raw for sale at the market, obtained at the market and farms, respectively. A total of 128 samples of leafy greens (chives, parsley, cabbage, arugula, watercress, and chicory) and 14 water samples were analyzed by direct immunofluorescence and PCR techniques. The positive samples were genotyped (GHD gene) using PCR and restriction fragment length polymorphism. The analyses indicated that 16 (12.5%) of 128 samples were positive by PCR, while 1 (0.8%) of 128 samples were positive by immunofluorescence. Giardia cysts were not detected in the water samples obtained at the farms. The molecular technique revealed a genotype with zoonotic potential, which underscores the challenge in the control of giardiasis dissemination via the consumption of raw vegetables.

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

“…The most widely used solutions are normal saline [14,[17][18][19][20] and phosphate-buffered saline [12,[21][22][23][24]. The commonly used solutions are glycine [11,25], sodium dodecyl sulfate [26], Alconox ® [27], and Tween 80 [28]. Other unusual solutions, such as 10% formal saline [29] and 0.1% peptone water [30] are also reported to isolate the contaminating parasites.…”

“…The other is membrane filtration (more commonly and effectively used), in which the deposit is collected by centrifugation. Membrane filtration devices include stomacher bags [23,30], zipper bags [22,24], sieves [18], gauze [21], or cellulose acetate membranes [28].…”

“…The PCR amplification and sequencing of specific G. duodenalis genes recovered from contaminated food are also commonly used for the confirmatory detection of this parasite (e.g. [28,39,44]).…”

“…The contamination of vegetables and fruits with G. duodenalis cysts has been reported in many countries (Table 2), and the average prevalence is estimated as 4.8% (276/5739; 95% CI: 4.2-5.4%). In contaminated vegetable and fruit samples, G. duodenalis zoonotic assemblages A and B were commonly detected [23,28,39,44,45].…”

“…of samples tested No. of positive samples (%) Giardia duodenalis assemblages identified ( n ) References Bangladesh Iodine and normal saline wet mount Vegetables 200 2 (1.0) [ 52 ] Brazil PCR Lettuce and chicory 11 2 (18.2) Assemblage BIV (2) [ 39 ] Brazil Immunofluorescence, PCR Arugula 4 2 (50.0) Assemblage AII (2) [ 28 ] Chives 12 1 (8.3) Assemblage AII (1) Crisp lettuce 32 4 (12.5) Assemblage AII (4) Greens collard 24 1 (4.2) Assemblage AI (1) Parsley 12 2 (16.7) Assemblage AII (2) Watercress 12 4 (33.3) Assemblage AII (4) Wild chicory 12 2 (16.7) Assemblage AII (2) Brazil Semi-nested PCR Regular lettuce 60 8 (13.3) Assemblage AI (4); Assemblage B (1); Assemblage E (1); N/D (2) [ ...…”