Detection of parasites in commonly consumed raw vegetables

Background: Ingestion of raw vegetables represented an important mean of transmission of several infectious diseases. No previous surveys have been conducted to evaluate the prevalence of parasitic contamination of vegetables in Egypt. Therefore, this study aimed to detect the parasitic contamination in some common raw vegetables in Alexandria, Egypt. Methods: It was based on: extraction of parasitic stages from the foodstuffs, concentration of the extract by centrifugation, staining of the different stages by modified Zeihl-Neelsen stain and modified trichrome stain to allow visualization of protozoal oocysts and spores of Microsporidium, and identification by microscopy. Scores of parasite density were evaluated. Results: Intestinal parasites were detected in 31.7% of the examined samples. The parasites included Ascaris lumbricoides eggs, Toxocara spp. eggs, Hymenolepis nana eggs, Giardia spp. cysts, Cryptosporidium spp. oocysts, Cyclospora spp. oocysts and Microsporidium spp. spores. The highest number of contaminated samples was detected in rocket (46.7%) while the least number of contaminated samples was detected in green onion (13.3%). Cryptosporidium spp. oocysts were considered the highest prevalent parasite detected in raw vegetables (29.3%) with the highest score density in rocket samples. It was followed by Microsporidium spp. spores (25.3%), Cyclospora spp. oocysts (21.3%), A. lumbricoides eggs (20.3%), Toxocara spp. eggs (19%), Giardia spp. cysts (6.7%) and finally H. nana eggs (2.6%). There was no significant difference between the number of contaminated samples in spring and summer or autumn and winter. However, the number was significantly higher in spring and summer in comparison to winter and autumn (p < 0.001). Conclusion: These findings may have important implications for global food safety and emphasize the importance of raw vegetables in threatening public health by transmission of intestinal parasites to humans in Alexandria, Egypt. (C) 2012 Alexandria University Faculty of Medicine. Production and hosting by Elsevier B.V. All rights reserved.