Prevalence and subtype identification of Blastocystis isolated from humans in Ahvaz, Southwestern Iran

Aim: The aim of the present study was to determine the prevalence and subtype distribution of Blastocystis and its relation with demographic data and symptoms in humans referred to medical centers in Ahvaz 2014-2015. Background: Infections with intestinal parasites are one of the most important threats to human health worldwide, especially in tropical and subtropical areas. Blastocystis sp. is a common parasite of humans with a vast variety of non-human hosts. We aimed to study the prevalence and subtypes of Blastocystis sp. in individuals referred to medical laboratories in Ahvaz city, southwest Iran. Methods: From September 2014 to September 2015, 618 stool samples were collected from 16 medical laboratories in Ahvaz, and examined using direct wet mount, formalin-ether concentration, a modified version of the Ziehl–Neelsen staining technique, and cultivation in xenic HSr + S medium. Subtypes of positive Blastocysts sp. were obtained using the “barcoding” method. The results were analyzed using SPSS software, version 16, with Chi-square and Fisher’s exact test. Results: Totally, 325 (52.6%) of the referred individuals were men and 293 (47.4%) were women. Blastocystis sp. was observed in 146 (23.6%) samples. Co-infections with other intestinal parasites were found in 32 (5.17%) cases. Out of the 146 positive isolates, 20.83%, 20.83% and 58.34% belonged to ST1, ST2, ST3 respectively. Conclusion: Blastocystis sp. was quite common in the study population, with a carrier rate corresponding to nearly one in every four individuals. The subtype distribution identified in the present study was largely identical to that reported from other studies in Iran, with ST3 being the most common.