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Berries as a potential transmission vehicle for taeniid eggs

Sanna Malkamäki, Anu Näreaho, Antti Oksanen, Antti Sukura
Parasitology international 2019 v.70 pp. 58-63
DNA, NADH dehydrogenase, Taenia, Vaccinium myrtillus, Vaccinium vitis-idaea, bilberries, chitin, detection limit, egg shell, eggs, fluorescence, forests, genes, humans, microscopy, mitochondria, models, oligodeoxyribonucleotides, quantitative polymerase chain reaction, risk, shrubs, spraying
Potential role of wild forest berries as a transmission vehicle for taeniid eggs was examined using non-zoonotic Taenia laticollis eggs as a model. The berries studied were bilberries (Vaccinium myrtillus) (1 m2 plot, n = 10) and lingonberries (Vaccinium vitis-idaea) (1 m2 plot, n = 11). The plots in the managed forest were evenly sprayed with 30,000 or 60,000 T. laticollis eggs suspended in water, and berries were collected 24 h after spraying. The berries were rinsed with water, and the water was sieved through a 1-mm and a 63-μm sieve to remove coarse material and through a 20-μm sieve to collect possible eggs. A small proportion of the sieved material was examined by microscopy after treatment with fluorescent Calcofluor White stain, which binds to eggshell chitin. In the recovery tests in artificially spiked samples, the detection limit was 5 eggs in 100 g of commercial frozen bilberries and lingonberries. Taeniid eggs were detected in all of the 10 experimentally contaminated bilberry samples and in 10 of 11 lingonberry samples. The sieved debris was also analyzed for T. laticollis DNA using semi-quantitative PCR. All samples were positive in quantitative SYBR Green real-time PCR using a T. laticollis-specific primer pair amplifying a short fragment of mitochondrial NADH dehydrogenase subunit 1 gene. This indicates that forest berries contaminated in shrubs contained T. laticollis eggs, and that berries can serve as a vehicle for taeniid eggs and may pose a possible risk to humans.