Abstract
Blastocystis sp. is described as an enteric protist prevalent in fecal samples from humans and animals; its pathogenicity and epidemiology are still controversial. Currently, it has been associated with intestinal diseases such as irritable bowel syndrome and clinical manifestations of allergic skin, such as chronic urticaria. In the context of urticaria, it is still uncertain whether this organism is directly related to the allergic manifestation or just a common component of the intestinal microbiota. This study aimed to evaluate the occurrence and molecular diversity of Blastocystis sp. in individuals with urticaria from a dermatology outpatient clinic, São Paulo, Brazil. Fecal samples of 58 patients with urticaria were examined using parasitological methods; and subsequently tested by polymerase chain reaction using Blastocystis-specific primers. The subtypes (STs) and alleles (a) were determined using BLASTn and MLST tools. ST1, ST2, ST3, ST4, ST6 and mixed infection (ST1 + ST3) were identified in the patients with urticaria; ST1 (a4), ST3 (a34 and a36) and ST4 (a42) were the most prevalent. Our molecular analyses allowed an initial description of Blastocystis subtypes in patients with urticaria from São Paulo city, Brazil.