Saarma, U. | bioRxiv Science

bioRxiv2024

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

Cystic and alveolar echinococcosis are severe zoonotic diseases characterized by long asymptomatic periods lasting months or years. Viable Echinococcus eggs 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. Both Echinococcus multilocularis and Echinococcus granulosus sensu lato are 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 of Echinococcus spp. to humans. Two multicenter and multicountry studies were conducted within the One Health EJP framework to estimate the proportion of lettuces and berries contaminated by E. 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 multilocularis DNA 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 for E. granulosus s.l., E. granulosus sensu stricto DNA was identified in 1.3% of lettuces (9/695). The proportion of lettuces contaminated by E. granulosus sensu stricto DNA was 12% (9/75) in Tunisia and 4% (4/100) in Pakistan. Regarding berries, E. multilocularis DNA 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 of E. granulosus s.s were 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 of Echinococcus species 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 by Echinococcus eggs.

microbiology↗

bioRxiv2022

Genomes of the extinct Sicilian wolf reveal a complex history of isolation and admixture with ancient dogs

The Sicilian wolf represented the only population of wolves living on a Mediterranean island until the first half of the twentieth century (1930s-1960s) 1-7. Previous studies hypothesised that they remained isolated from mainland wolves from the end of the Last Glacial Maximum (LGM) 8,9, until human persecutions led them to extinction 1-7. There are only seven known Sicilian wolf specimens from the 19th and 20th century preserved in museums in Italy and recent morphometric analyses assigned them to the new subspecies Canis lupus cristaldii 10. To better understand the origins of the Sicilian wolf, and its relationship to other wolf populations, we sequenced four whole genomes (3.8x-11.6x) and five mitogenomes. We investigated the relationship between Sicilian wolves and other modern breeds to identify potential admixture. Furthermore, considering that the last land-bridge between Sicily and Italy disappeared after the LGM 11, around 17 kya, we explored the possibility that the Sicilian wolf retained ancestry from ancient wolf and dog lineages. Additionally, we explored whether the long-term isolation might have affected the genomic diversity, inbreeding levels and genetic load of the Sicilian wolf. Our findings show that the Sicilian wolves shared most ancestry with the modern Italian wolf population but are better modelled as admixed with European dog breeds, and shared traces of Eneolithic and Bronze age European dogs. We also find signatures of severe inbreeding and low genomic diversity at population and individual levels due to long-term isolation and drift, suggesting also low effective population size.

genomics↗