Acanthamoeba spp. are free-living amoebae which are ubiquitously distributed worldwide and can be found in the wide range of environments, particularly in various types of water sources, where they able to cause important health problems. In the present study, cultures containing Acanthamoeba from water samples were obtained from our earlier survey. For an analysis of the genetic pattern of Acanthamoeba isolates, DNA sequencing of nuclear small-subunit rRNA gene (18S rRNA or Rns) was applied. A phylogenetic analyses of the isolates displayed that all of them were belonged to the potentially pathogenic T4 genotype. This investigation provides further evidence that the T4 genotype is the most prevalent in water samples and demonstrates that there is a need for taking more consideration to water sources in order to prevent complications associated with pathogenic Acanthamoeba spp.

Acanthamoeba has two developmental stages in its life cycle trophozoite and cyst, [5]. The trophozoite, is an active form, which the genus of Acanthamoeba is able to feed, grow, move and reproduce, and the cyst, is a non-active form. The double-layered coat cyst of this amoeba is resistant to disinfectants, antibiotics, UV radiation, and the chemical agents. Furthermore, it can survive as Journal of Human, Environment and Health Promotion Journal homepage: www.zums.ac.ir/jhehp Background: The genus of Acanthamoeba is an opportunistic protozoan parasite with a worldwide distribution where it is able to cause fatal granulomatous amoebic encephalitis (GAE) and amoebic keratitis (AK). This organism inhabits in the wide range of natural and man-made aquatic environments. The present study was carried out to evaluate the presence of Acanthamoeba spp. in the various water resources of Zanjan province, northwest Iran, using both morphological and molecular methods. Methods: The Water samples were randomly collected from 30 water sources in different parts of Zanjan, Iran, between April 2015 and May 2016. Then, the samples were cultured on non-nutrient agar and the Acanthamoeba genus identified by morphological characters. The polymerase chain reaction (PCR) was performed using the 18S rRNA gene as a molecular marker. Results: The obtained data showed that, out of the 60 water samples collected, 30 (50%) were positive for Acanthamoeba spp. According to morphological and molecular approaches. Conclusion: The present investigation is the first report of the distribution of Acanthamoeba spp. in the various water sources of Zanjan province, gives baseline knowledge regarding water contamination with Acanthamoeba spp. in these areas and emphasizes the necessity of more attention to water sources in order to prevent infections associated with Acanthamoeba spp.