title: Contribution of environmental media to cryptosporidiosis and giardiasis prevalence in Tehran: a focus on surface waters.
abstract: The occurrences of Cryptosporidium and Giardia in surface sources of drinking water in Tehran were monitored, using US EPA method 1623.1. The prevalence ratios (PR) of positive samples among other media (animal's stools, vegetables, and human's stools) were also estimated from literature data. The density of Giardia and Cryptosporidium in water samples were 0.129 ± 0.069 cysts/L and 0.005 ± 0.002 oocysts/L, respectively. Estimated PR in vegetables, animal stools, surface waters, and human stools were 6.65, 20.42, 21.05, and 4.28 % for Cryptosporidium and 6.46, 17.13, 73.68, and 15.65 % for Giardia, respectively. These reveal the importance of surface waters' and animal stools' roles in the prevalence of cryptosporidiosis and giardiasis in Tehran's population. Giardia's prevalence in untreated surface waters in Tehran was found 3.5 times as much as Cryptosporidium while this found 2.3 times on a global scale. Moreover, the prevalence of giardiasis to cryptosporidiosis infections in Tehran's human population was 3.65. These values could be a clue to attribute the infections to the occurrence of parasites in surface waters. Significant (p < 0.05) associations were observed between rainfalls and presence of Giardia (r = 0.62) and Cryptosporidium (r = 0.60) in surface waters. In autumn, rainfalls can increase the parasites occurrences in surface waters. Significant (p < 0.05) difference on the density of parasites was found between some seasons using Kruskal-Wallis and multiple comparison tests. A significant correlation (r = 0.86) between Giardia and Cryptosporidium densities also confirms the common sources of pollution in surface waters. Findings suggest that untreated surface waters in Tehran may be a potential route of human exposure to protozoan parasites.
authors.affiliation: Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Hadi
authors.affiliation: Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran. mesdaghinia@sina.tums.ac.ir.|Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. mesdaghinia@sina.tums.ac.ir.
authors.forename: Alireza
authors.initials: A
authors.lastname: Mesdaghinia
authors.affiliation: Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.|Center for Air Pollution Research (CAPR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Masud
authors.initials: M
authors.lastname: Yunesian
authors.affiliation: Center for Water Quality Research (CWQR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.|Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Simin
authors.initials: S
authors.lastname: Nasseri
authors.affiliation: Department of Environmental Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.|Center for Air Pollution Research (CAPR), Institute for Environmental Research (IER), Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Ramin
authors.initials: R
authors.lastname: Nabizadeh Nodehi
authors.affiliation: Department of Environmental Health Engineering, School of Public Health, Islamic Azad University-Tehran Medical Branch, Tehran, Iran.
authors.forename: Hamidreza
authors.initials: H
authors.lastname: Tashauoei
authors.affiliation: Department of Water and Wastewater Quality Control Laboratory, Water and Wastewater Company, Tehran, Iran.
authors.forename: Esfandiar
authors.initials: E
authors.lastname: Jalilzadeh
authors.affiliation: Department of Water and Wastewater Quality Control Laboratory, Water and Wastewater Company, Tehran, Iran.
authors.forename: Roya
authors.initials: R
authors.lastname: Zarinnejad
mesh_terms: D000818:Animals; D003457:Cryptosporidiosis / Q000453:epidemiology*; D003458:Cryptosporidium / Q000254:growth & development*; D060766:Drinking Water / Q000469:parasitology; D004777:Environment; D004784:Environmental Monitoring; D005243:Feces; D005618:Fresh Water / Q000469:parasitology*; D005872:Giardia / Q000254:growth & development*; D005873:Giardiasis / Q000453:epidemiology*; D006801:Humans; D007492:Iran / Q000453:epidemiology; D033661:Oocysts; D015995:Prevalence; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods; D014881:Water Supply
chemical_list: D060766:Drinking Water
keywords: Cryptosporidium; Giardia; Parasites occurrence; Protozoan parasites; Surface water