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A sensitive, one-way sequential sieving method to isolate helminths’ eggs and protozoal oocysts from tettuce for genetic identification


Guggisberg, Annina R; Alvarez Rojas, Cristian A; Kronenberg, Philipp A; Miranda, Nadia; Deplazes, Peter (2020). A sensitive, one-way sequential sieving method to isolate helminths’ eggs and protozoal oocysts from tettuce for genetic identification. Pathogens, 9(8):E624.

Abstract

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 Toxocara canis, Echinococcus multilocularis and oocysts of Toxoplasma gondii) were used to investigate the practicability and sensitivity of the method. The detection limits (100% positive results) in the recovery experiments were four Toxocara eggs, two E. multilocularis eggs and 18 T. gondii oocysts (in 4/5 replicates). In a field study, helminth DNA was detected in 14 of 157 lettuce samples including Hydatigera taeniaeformis (Syn. Taenia taeniaeformis) (four samples), T. polyacantha (three), T. martis (one), E. multilocularis (two) and Toxocara cati (four). Toxoplasma gondii was detected in six of 100 samples. In vivo testing in mice resulted in metacestode growth in all animals injected with 40–60 E. multilocularis 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.

Abstract

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 Toxocara canis, Echinococcus multilocularis and oocysts of Toxoplasma gondii) were used to investigate the practicability and sensitivity of the method. The detection limits (100% positive results) in the recovery experiments were four Toxocara eggs, two E. multilocularis eggs and 18 T. gondii oocysts (in 4/5 replicates). In a field study, helminth DNA was detected in 14 of 157 lettuce samples including Hydatigera taeniaeformis (Syn. Taenia taeniaeformis) (four samples), T. polyacantha (three), T. martis (one), E. multilocularis (two) and Toxocara cati (four). Toxoplasma gondii was detected in six of 100 samples. In vivo testing in mice resulted in metacestode growth in all animals injected with 40–60 E. multilocularis 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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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:05 Vetsuisse Faculty > Veterinärwissenschaftliches Institut > Institute of Parasitology
04 Faculty of Medicine > Institute of Parasitology
Dewey Decimal Classification:570 Life sciences; biology
610 Medicine & health
600 Technology
Scopus Subject Areas:Health Sciences > Immunology and Allergy
Life Sciences > Molecular Biology
Life Sciences > General Immunology and Microbiology
Health Sciences > Microbiology (medical)
Health Sciences > Infectious Diseases
Language:English
Date:31 July 2020
Deposited On:01 Sep 2020 15:01
Last Modified:24 Jul 2024 01:35
Publisher:MDPI Publishing
ISSN:2076-0817
OA Status:Gold
Free access at:PubMed ID. An embargo period may apply.
Publisher DOI:https://doi.org/10.3390/pathogens9080624
PubMed ID:32751811
  • Content: Published Version
  • Language: English
  • Licence: Creative Commons: Attribution 4.0 International (CC BY 4.0)