Washing methods to avoid parasitic contamination of raw vegetables in Assiut, Egypt: A comparative efficacy study "

Background: Investigating simple, low-cost household washing methods is critical to avoid parasitic infections before consumption of fresh vegetables. Objective: To evaluate the effect of commonly feasible household washing methods, and identify the most effective one for eliminating diverse infective parasitic stages. Material and Methods: A total of 202 samples of 6 different raw consumable vegetables were collected from local markets in Assiut, Egypt, and microscopically examined to confirm parasitic contamination. Each sample (~50 g) was subjected to four washing treatments: direct rinsing with distilled water (DW) and immediate removal (W1), soaking in diluted vinegar (4:1) for one hour (W2), soaking in DW for 1, and 24 h (W3, and W4, respectively). To provide quantitative and qualitative measures of decontamination efficacy, the wastewater of each wash was subjected to parasitological examination to assess parasite contamination frequency, and viability rate (%). Results: Among all tested methods, the vinegar-based washing method (W2) demonstrated optimal efficacy. It exhibited 82% reduction in pathogenic protozoan contamination, the highest decontamination rate. Prolonged soaking (W4) showed moderate efficacy (68% contamination reduction), while brief rinsing (W1) was the least effective. For helminth contaminants, W1 and W2 showed comparable efficacy (55-60% reduction, respectively). Although W2 achieved maximal pathogen inactivation (only 15.8% viable stages remaining) a significant (P<0.01) result versus other methods. No method eliminated all pathogenic stages, demonstrating the need for combined preventive approaches. Conclusion: Soaking in diluted vinegar not only eliminates infective parasitic stages more effectively, but also inactivates them, making it superior for ingestion of raw vegetables.