Summary: | Different helminths and protozoa are transmitted to humans by oral uptake of environmentally resistant parasite stages after hand-to-mouth contact or by contaminated food and water. The aim of this study was to develop and validate a method for the simultaneous detection of parasite stages from fresh produce (lettuce) by a one-way isolation test kit followed by genetic identification (PCR, sequencing). Three sentinel zoonotic agents (eggs of <i>Toxocara canis</i>, <i>Echinococcus multilocularis</i> and oocysts of <i>Toxoplasma gondii</i>) were used to investigate the practicability and sensitivity of the method. The detection limits (100% positive results) in the recovery experiments were four <i>Toxocara</i> eggs, two <i>E. multilocularis</i> eggs and 18 <i>T. gondii</i> oocysts (in 4/5 replicates). In a field study, helminth DNA was detected in 14 of 157 lettuce samples including <i>Hydatigera taeniaeformis</i> (Syn. <i>Taenia taeniaeformis</i>) (four samples), <i>T</i>. <i>polyacantha</i> (three), <i>T</i>. <i>martis</i> (one), <i>E</i>. <i>multilocularis</i> (two) and <i>Toxocara cati</i> (four). <i>Toxoplasma gondii</i> was detected in six of 100 samples. In vivo testing in mice resulted in metacestode growth in all animals injected with 40–60 <i>E. multilocularis</i> eggs, while infection rates were 20–40% with 2–20 eggs. The developed diagnostic strategy is highly sensitive for the isolation and genetic characterisation of a broad range of parasite stages from lettuce, whereas the sensitivity of the viability tests needs further improvement.
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