Environmental contamination with parasites in selected rural farms in the Philippines: impacts of farming practices on leafy greens food safety

Abstract

Fresh vegetables are an important part of a healthy diet, however, they can also be agents of transmission of intestinal parasites. This study aimed to evaluate the presence of parasite contamination in vegetable farms as a source of transmission in selected rural communities in Laguna, Philippines. A total of 168 vegetable, 55 soil and 15 water samples collected from four selected farms and a reference farm were processed through various standard parasitological techniques. Of these, 17.3% of vegetables, 47.3% soil and 73.3% water samples were found contaminated with parasites’ eggs or cysts. Interestingly, leafy vegetables, such as lettuce, were found to be more contaminated. Results showed that strongylids/hookworms (egg/larva) showed the highest prevalence in farm soil (38.2%) and vegetable (13.1%); other helminth parasite eggs were also recovered such as Toxocara sp., Ascaris sp., Trichiuris, Trichostrongylus sp. and protozoan cysts of Balantidium coli. Cryptosporidium sp. oocysts of and Giardia sp. cysts were observed in all water samples in the farms. Furthermore, results revealed that some farming practices such as the use of improperly treated animals manure as fertilizers, unhygienic practice of farmers and sanitation issues were factors that contribute to parasite contamination in the farms. These findings have implications on food safety in poor-resource communities posing public health risks. Recommendations were discussed in the study for the control and prevention of parasite contamination at the farm level.

First report demonstrating the presence of Toxocara spp. eggs on vegetables grown in community gardens in Europe

“…Discovering Toxocara eggs within the soil used to cultivate vegetables in this study was not entirely unexpected given the presence of these eggs on vegetable crops. This finding is supported by similar studies undertaken in other countries, such as the Philippines ( Paller et al, 2021 ) and Poland ( Klapec and Borecka, 2012 ). Given the small number of soil samples tested in this pilot study, firm comparisons between the prevalence of eggs on vegetable produce and soil cannot be drawn.…”

“…Leafy vegetables such as lettuces have been reported to have higher susceptibility to contamination with Toxocara spp. eggs compared to non-leafy vegetables, possibly due to the folded nature of the leaves, which capture more soil during cultivation ( Hajipour et al, 2021 ; Abougrain et al, 2010 ; Paller et al, 2021 ). This is consistent with the current study, where both positive vegetable samples were from lettuces.…”

Detection of Giardia duodenalis and Toxoplasma gondii in soil and water samples in the Quindío River basin, Colombia

“…It is important to highlight that soil is increasingly recognized as an important source of transmission of T. gondii ( Afonso et al, 2008 ; Escotte-Binet et al, 2019 ) and G. duodenalis ( Balderrama-Carmona et al, 2014 ; Lee et al, 2021 ; Omeragić et al, 2021 ; Paller et al, 2022 ) . However, detecting the presence and estimating the load of T. gondii in soil has been difficult given limitations in the availability of detection methods ( Shapiro et al, 2019a , Shapiro et al, 2019b ).…”

“…Documenting the degree of soil contamination with T. gondii oocysts and G. dudodenalis cysts is fundamental to propose efficacious measures to prevent toxoplasmosis and giardiasis ( Slifko et al, 2000 ; Escotte-Binet et al, 2019 ; Dumètre et al, 2012 ; Lee et al, 2021 ; Paller et al, 2022 ). Molecular assays are currently the most sensitive and effective methods to detect T. gondii and G. dudoenalis in soil ( Orlofsky et al, 2013 ; Shapiro et al, 2019a ; Slifko et al, 2000 ).…”

From fox to fork? Toxocara contamination of spinach grown in the south of England, UK

“…For example, Toxocara spp. eggs were detected on 4.8% of sampled vegetables in a study undertaken in the Philippines, with leafy vegetables found to be most contaminated [5], and in a Brazilian study, 17.8% of sampled lettuces (Lactuca sativa) were found to be positive for Toxocara spp. eggs [6].…”