Detection ofEchinococcusspp. and other taeniid species in lettuces and berries: two international multicenter studies from the MEmE project

Abstract

Cystic and alveolar echinococcosis are severe zoonotic diseases characterized by long asymptomatic periods lasting months or years. ViableEchinococcuseggs released into the environment through the feces of canids can infect humans through accidental ingestion via hand-to-mouth contact or consumption of contaminated food or water. BothEchinococcus multilocularisandEchinococcus granulosus sensu latoare considered as foodborne parasites. However, when considering possible pathways of human infection, it appears that food and water-borne related variables do not significantly increase the risk of infection. Providing evidence-based data for the presence of DNA and, potentially, eggs in fresh produce is crucial in understanding foodborne transmission ofEchinococcusspp. to humans. Two multicenter and multicountry studies were conducted within the One Health EJP framework to estimate the proportion of lettuces and berries contaminated byE. multilocularis,E. granulosus s.l., and other taeniid DNAs from 12 European countries, Tunisia and Pakistan. A total of 1,117 lettuces, 300 strawberries and 130 blueberries samples were collected and analyzed by washing, sequential sieving and real-time PCRs.Echinococcus multilocularisDNA was detected in 1.2% (7/570) of samples tested from the seven European endemic areas and in 2% (2/100) from Pakistan. In the five European endemic countries forE. granulosus s.l.,E. granulosus sensu strictoDNA was identified in 1.3% of lettuces (9/695). The proportion of lettuces contaminated byE. granulosus sensu strictoDNA was 12% (9/75) in Tunisia and 4% (4/100) in Pakistan. Regarding berries,E. multilocularisDNA was detected in 5.4% of strawberries (n=11/202), 7.3% of blueberries (6/82) from the seven European endemic countries and 56% of blueberries (14/25) from Pakistan. High contamination rates ofE. granulosus s.swere found outside of Europe, with 12.0% in blueberries (3/25) from Pakistan and 81.3%. DNA in strawberries (13/16) from Tunisia. The total contamination rate of all taeniid species DNA in lettuces (5.3%; 59/1,117) and berries (12.1%; 58/480) suggests that the transfer of taeniid eggs from carnivore feces to food is not uncommon. Although we assume that eggs are the source of the DNA detected in this study, the viability of such eggs is unknown. The detection ofEchinococcusspecies in lettuces and berries suggests a potential risk of foodborne human infection. The relative contribution of this risk remains to be estimated. Further studies on food and environmental contamination are necessary to cover different epidemiological contexts and social habits, leading to a better understanding of human infections byEchinococcuseggs.