Aim: The aim of the present study was to simultaneously investigate parasitic contamination of treated wastewater and downstream
vegetable farms that are irrigated with treated sewage, during a year.
Background: (Oo) Cysts and eggs of parasites are resistant to most of routine wastewater treatment process. Irrigation of vegetables
farms with either treated wastewater or illegally use of raw wastewaters enhances the risk of contamination with enteric pathogens.
Methods: The treated wastewater samples were taken after chlorination from a wastewater treatment plant located at the south of
Tehran. In addition, 60 vegetable samples (5 samples from each farm) were collected from the selected downstream farms that
routinely used treated wastewater for irrigation of crops. Parasitological tests were performed using Ziehl–Neelsen, conventional
lugol’s iodine staining and direct microscopical examination.
Results: Parasites including free living larvae, eggs of Toxoascaris leonina, egg of Toxocara sp. Trichuris sp, Trichostrongylus sp
and amoeboid trophozoite were seen in 5/12 (41.7%) of vegetable samples gathered during a year. There was no statistically
significant correlation between the season and parasitic contamination of the vegetables (P= 1). Furthermore, parasitic contamination
was observed in 7/12 (53.8%) of treated wastewater samples. The correlation between season and parasitic contamination of treated
wastewater was evaluated that the results showed a higher contamination of treated wastewater in spring and autumn (P<0.05).
Fisher’s exact test also showed that there was no significant correlation between parasitic contaminations of vegetable samples and
treated wastewater according to seasonal change.
Conclusion: The results showed parasites in both treated wastewater plant and downstream crops farms that suggests the public
health importance of the quality of water resources that routinely used for irrigation of vegetable farms.
Keywords: Treated wastewaters, Vegetable farms, Irrigation, Parasitic contamination, Iran.
(Please cite as: Javanmard E, Mirjalali H, Niyyati M, Sharifdini M, Jalilzadeh E, Seyed Tabaei SJ, et al. Small-scale
risk assessment of transmission of parasites from wastewater treatment plant to downstream vegetable farms.
Gastroenterol Hepatol Bed Bench 2018;11(4):352-358).
Su LJ, Arab L. Salad and raw vegetable consumption and nutritional status in the adult US population: results from the Third National Health and Nutrition Examination Survey. J Am Diet Assoc. 2006;106(9):1394-404.
Van Duyn MA, Pivonka E. Overview of the health benefits of fruit and vegetable consumption for the dietetics professional: selected literature. J Am Diet Assoc. 2000;100(12):1511-21.
Liu X, Yan Y, Li F, Zhang D. Fruit and vegetable consumption and the risk of depression: A meta-analysis. Nutrition (Burbank, Los Angeles County, Calif). 2016;32(3):296-302.
Wu QJ, Wu L, Zheng LQ, Xu X, Ji C, Gong TT. Consumption of fruit and vegetables reduces risk of pancreatic cancer: evidence from epidemiological studies. Euro J Cancer Preven : the official journal of the European Cancer Prevention Organisation (ECP). 2016;25(3):196-205.
Hou Z, Fink RC, Radtke C, Sadowsky MJ, Diez-Gonzalez F. Incidence of naturally internalized bacteria in lettuce leaves. Int J Food Microbiol. 2013;162(3):260-5.
Park S, Szonyi B, Gautam R, Nightingale K, Anciso J, Ivanek R. Risk factors for microbial contamination in fruits and vegetables at the preharvest level: a systematic review. J Food Protect. 2012;75(11):2055-81.
Amoah ID, Abubakari A, Stenstrom TA, Abaidoo RC, Seidu R. Contribution of Wastewater Irrigation to Soil Transmitted Helminths Infection among Vegetable Farmers in Kumasi, Ghana. PLoS Neg Trop Dis. 2016;10(12):e0005161.
Jiménez B. Irrigation in developing countries using wastewater. Inter Rev Environ Strategies. 2006;6(2):229-50.
Wichelns D, Drechsel P, Qadir M. Wastewater: Economic asset in an urbanizing world. Wastewater: Springer; 2015. p. 3-14.
Evans AEV, Hanjra MA, Jiang YL, Qadir M, Drechsel P. Water Quality: Assessment of the Current Situation in Asia. Int J Water Resour D. 2012;28(2):195-216.
United Nations. Water for people, water for life. The United Nations world water development report Barcelona: UNESCO; 2003
Mara D, Sleigh A. Estimation of norovirus and Ascaris infection risks to urban farmers in developing countries using wastewater for crop irrigation. J Water Health. 2010;8(3):572-6.
Anuar TS, Salleh FM, Moktar N. Soil-transmitted helminth infections and associated risk factors in three Orang Asli tribes in Peninsular Malaysia. Sci Rep. 2014;4:4101.
Pham-Duc P, Nguyen-Viet H, Hattendorf J, Zinsstag J, Phung-Dac C, Zurbrugg C, et al. Ascaris lumbricoides and Trichuris trichiura infections associated with wastewater and human excreta use in agriculture in Vietnam. Parasitol Int. 2013;62(2):172-80.
United Nations. Water and Sanitation the Pathway to a Sustainable Future Geneva: United Nations; 2015 [
Hatam Nahavandi K, Mahvi AH, Mohebali M, Keshavarz H, Rezaei S, Mirjalali H, et al. Molecular Typing of Eimeria ahsata and E. crandallis Isolated From Slaughterhouse Wastewater. Jundishapur J Microbiol. 2016;9(4):e34140.
Hatam-Nahavandi K, Mohebali M, Mahvi AH, Keshavarz H, Najafian HR, Mirjalali H, et al. Microscopic and Molecular Detection of Cryptosporidium andersoni and Cryptosporidium xiaoi in Wastewater Samples of Tehran Province, Iran. Iran J Parasitol. 2016;11(4):499-506.
Hatam-Nahavandi K, Mohebali M, Mahvi AH, Keshavarz H, Mirjalali H, Rezaei S, et al. Subtype analysis of Giardia duodenalis isolates from municipal and domestic raw wastewaters in Iran. Environ Sci Pollut Res Int. 2017;24(14):12740-7.
Lonigro A, Rubino P, Lacasella V, Montemurro N. Faecal pollution on vegetables and soil drip irrigated with treated municipal wastewaters. Agric Water Manag. 2016;174:66-73.
Kuroda K, Nakada N, Hanamoto S, Inaba M, Katayama H, Do AT, et al. Pepper mild mottle virus as an indicator and a tracer of fecal pollution in water environments: comparative evaluation with wastewater-tracer pharmaceuticals in Hanoi, Vietnam. Sci Total Environ. 2015;506-507:287-98.
Forslund A, Plauborg F, Andersen MN, Markussen B, Dalsgaard A. Leaching of human pathogens in repacked soil lysimeters and contamination of potato tubers under subsurface drip irrigation in Denmark. Water Res. 2011;45(15):4367-80.
Burnet JB, Penny C, Ogorzaly L, Cauchie HM. Spatial and temporal distribution of Cryptosporidium and Giardia in a drinking water resource: implications for monitoring and risk assessment. Sci Total Environ. 2014;472:1023-35.
Hobbs SH. Attitudes, practices, and beliefs of individuals consuming a raw foods diet. Explore (New York, NY). 2005;1(4):272-7.
Losio MN, Pavoni E, Bilei S, Bertasi B, Bove D, Capuano F, et al. Microbiological survey of raw and ready-to-eat leafy green vegetables marketed in Italy. Int J Food Microbiol. 2015;210:88-91.
Balkhair KS. Microbial contamination of vegetable crop and soil profile in arid regions under controlled application of domestic wastewater. Saudi J Biol Sci. 2016;23(1):S83-S92.
Gomez-Govea M, Solis-Soto L, Heredia N, Garcia S, Moreno G, Tovar O, et al. Analysis of microbial contamination levels of fruits and vegetables at retail in Monterrey, Mexico. J Food Agric Environ. 2012;10(1):152-6.
Drankin DI, Zaiats NA, Krylov BA, Reshetnikova VI, Riabinin NV, Kharitonova LP. [A water-borne outbreak of hepatitis A among students employed in agricultural operations on a vegetable-growing farm]. Zh Mikrobiol Epidemiol Immunobiol. 1995(6):33-4.
Jernberg C, Hjertqvist M, Sundborger C, Castro E, Lofdahl M, Paajarvi A, et al. Outbreak of Salmonella Enteritidis phage type 13a infection in Sweden linked to imported dried-vegetable spice mixes, December 2014 to July 2015. Euro Surveill. 2015;20(30).
Jung Y, Jang H, Matthews KR. Effect of the food production chain from farm practices to vegetable processing on outbreak incidence. Microb Biotechnol. 2014;7(6):517-27.
Karanis P, Kourenti C, Smith H. Waterborne transmission of protozoan parasites: a worldwide review of outbreaks and lessons learnt. J Water Health. 2007;5(1):1-38.
Shahnazi M, Jafari-Sabet M. Prevalence of Parasitic Contamination of Raw Vegetables in Villages of Qazvin Province, Iran. Foodborne Pathog Dis. 2010;7(9):1025-30.
Fallah AA, Pirali-Kheirabadi K, Shirvani F, Saei-Dehkordi SS. Prevalence of parasitic contamination in vegetables used for raw consumption in Shahrekord, Iran: Influence of season and washing procedure. Food Control. 2012;25(2):617-20.
Ezatpour B, Chegeni AS, Abdollahpour F, Aazami M, Alirezaei M. Prevalence of parasitic contamination of raw vegetables in Khorramabad, Iran. Food Control. 2013;34(1):92-5.
Mohamed MA, Siddig EE, Elaagip AH, Edris AMM, Nasr AA. Parasitic contamination of fresh vegetables sold at central markets in Khartoum state, Sudan. Ann Clin Microb Anti. 2016;15.
Adanir R, Tasci F. Prevalence of helminth eggs in raw vegetables consumed in Burdur, Turkey. Food Control. 2013;31(2):482-4.
Daryani A, Ettehad G, Sharif M, Ghorbani L, Ziaei H. Prevalence of intestinal parasites in vegetables consumed in Ardabil, Iran. Food control. 2008;19(8):790-4.
Ben Ayed L, Schijven J, Alouini Z, Jemli M, Sabbahi S. Presence of parasitic protozoa and helminth in sewage and efficiency of sewage treatment in Tunisia. Parasitol Res. 2009;105(2):393-406.
Gupta N, Khan DK, Santra SC. Prevalence of intestinal helminth eggs on vegetables grown in wastewater-irrigated areas of Titagarh, West Bengal, India. Food Control. 2009;20(10):942-5.
Mahvi AH, Kia EB. Helminth eggs in raw and treated wastewater in the Islamic Republic of Iran. East Mediterr Health J. 2006;12(1-2):137-43.
World Health Organization. Guidelines for the safe use of wastewater, excreta and greywater: World Health Organization; 2006.