Molecular epidemiology of Blastocystis infections in Turkey.

Blastocystis is a very common unicellular intestinal parasite of ubiquitous occurrence. In order to describe the molecular epidemiology of Blastocystis infections in Turkey, 87 isolates from 69 symptomatic and 18 asymptomatic individuals were sequenced. Sequence data were phylogenetically analyzed and statistically tested against unmodifiable risk factors such as gender and age. Blastocystis-positive males were complaining mainly of gastroenteritis, whereas dyspepsia was the chief complaint among Blastocystis-positive females. Blastocystis sp. subtypes detected in the study included subtypes 1, 2, 3 and 4, subtype 3 being the most predominant (75.9%). No association was detected between Blastocystis sp. subtype and symptoms (p>0.365), or between infection intensity and symptoms (p>0.441). There was a tendency of subtype 2 isolates being more common among older study individuals, and subtype 2 isolates were significantly associated with higher parasite abundance (p=0.017). Compared to data from similar studies, the distribution of Blastocystis sp. isolates in Turkey was found to more or less reflect the one seen in other countries, and it was deduced that subtype 3 is generally by far the most common subtype infecting humans, followed by subtypes 1, 2 and 4.