contamination of drinking water supplies in mazandaran - iran

introduction : direct relationship has been reported between the prevalence of some parasitic diseases and the presence of microorganisms in water. there are possible contamination of water resources, due to the climate changes and increasing the groundwater level. the purpose of this research was to determine the contamination rate of drinking water supplies to parasites in mazandaran province, north of iran, during 2002-2003. materials and methods : in this cross-sectional study, 989 water samples which randomly taken based on towns population and number of primary health care centers from 12 cities of mazandaran province. collected water samples were transferred to the laboratory in sterile containers and standard condition.  the samples were filtered and then analyzed according to the who guidelines. direct method and lugol staining procedure were used to identify the parasites. in cases of cryptosporidium presence, centrifugal flotation techniques using sheather's sugar solution and modified ziehl-neelsen staining method were performed. mcmaster counting slides were used for parasites count in 0.3ml.  results: almost 20% (197 out of 989) of water samples were contaminated with different parasites. 20 different types of parasites were identified in 197 contaminated samples, which 53 (26.9%) were pathogenic, 100 (50.8%) non-pathogenic, and 44 (22.3%) non-infective stages of parasites. conclusions : drinking water contamination to parasites has been reported about 15 percent in most of mazandaran areas. our findings confirmed increasing prevalence of intestinal parasitic infections in the other studies in this province. according to high prevalence of water contamination and its contributes to diseases, proper implementation of providing safe drinking water should be considered by water supply companies.