Molecular epidemiology of Blastocystis in urban and periurban human populations in Arequipa, Peru

Blastocystis is one of the most common parasites found in the gut of humans and other hosts. It has a wide genetic diversity distributed around the world, predominating subtypes 1, 2 and 3 in South America countries. Nonspecific and inconsistent symptoms associated with this parasite made it controversial. The aim of this study was to estimate the prevalence of subtypes and determinate the epidemiological conditions associated with them. A total of 116 Blastocystis positive stool samples were processed by conventional PCR with Blastocystis -specific primers for subtypes 1 to 3. We identified subtype 1 (10.3%), subtype 2 (7.6%), subtype 3 (25.0%) and mixed infections (8.6%). We did not identify these Blastocystis subtypes in 48.7% of stool samples, assuming the presence of other subtypes in the zone. Any association was found between gastrointestinal symptoms and single subtype infections neither with mixed subtypes coinfections. However, our results suggest an association of Blastocystis subtype 2 and Irritable Bowel Syndrome (IBS, p=0.039). Besides, there was not an association between Blastocystis subtypes 1, 2 and 3 nor-mixed infections with epidemiological variables such as gender, age, presence of animals or vectors, places of food consumption, type of water consumption and water supply.