Study of prevalence, distribution and clinical significance of Blastocystis isolated from two medical centers in Iran

Aim This study aimed to survey prevalence and clinical significance of Blastocystis among symptomatic and asymptomatic groups. Background Blastocystis is a prevalent microorganism that is found in intestine of human and majority of animals. However, most studies have failed to establish correlation between the presence of the parasite and clinical manifestations. Methods from Dec 2016 to Jun 2017, 554 stool samples were collected from symptomatic and asymptomatic subjects referred to Imam Hossein Hospital and Gastroenterology and Liver Diseases Research Institute, Tehran, Iran. All samples were concentrated using conventional formalin-ethyl acetate concentration and then were microscopically examined using Lugol's iodine staining and light microscope. The fresh stool samples were also cultivated in DMEM medium and were examined for growth of Blastocystis every 48 hours with direct smear slides for 10 days. Results Blastocystis was observed among 93 (16.8%) of stool samples cultivated in DMEM. The findings represented that 64/398 (16.08%) and 29/156 (18.58%) of asymptomatic and symptomatic patients were infected with Blastocystis, respectively. In addition, there was no significant correlation between presence of symptoms and carrying Blastocystis (P=0.528), although statistically significant association was observed between presence of urticaria and carrying Blastocystis (P<0.05). Furthermore, a statistically significant correlation between observing the parasite and different age groups was seen (P<0.05). Conclusion Blastocystis is a prevalent parasitic eukaryote among symptomatic and asymptomatic populations despite the higher prevalence among symptomatic group that suggests the chance of infection with Blastocystis raises with age.