Comparison of various diagnostic techniques for the detection of Blastocystis spp. and its molecular characterisation in farm animals in the United Arab Emirates

Introduction: Blastocystis spp. is a common anaerobic intestinal parasite infecting humans and a diverse range of animals. The aim of the study was to compare different diagnostic methods for the detection of Blastocystis and survey the occurrence of its subtypes in farm animals, namely sheep, cows and camels, in Al-Ain, United Arab Emirates. Material and Methods: Ninetyseven faecal samples comprised of 69 from sheep, 12 from cows and 16 from camels were submitted to DNA extraction, PCR and sequencing. Blastocystis was screened for microscopically in 65 samples using direct wet-mount, modified acid-fast staining, trichrome staining and in vitro culture techniques. Results: Fifteen (15.5%) samples were positive by PCR, twelve of which were confirmed by sequencing. Using PCR as a comparison standard, the sensitivity and specificity of the direct wet-mount, modified acid-fast staining, trichrome staining and in vitro culture methods were 40.0% and 78.3%, 40.0% and 83.3%, 80.0% and 80.0%, and 80.0% and 76.7% respectively. Only culture and trichrome tests were significantly associated with PCR (odds ratio (OR) = 13.14; 95% confidence interval (CI): 1.35-127.4; P = 0.007 and OR = 16; 95% CI: 1.63-156.5; P = 0.003, respectively) with trichrome detecting more positive cases than in vitro culture. The subtype (ST)10 was the only one found in all 12 sequenced sheep isolates. Conclusion: The study corroborated previous data indicating that sheep are the natural hosts for ST10. No zoonotic subtypes nor mixed-subtype colonisation were found. The report also confirmed the superiority of trichrome staining in detecting Blastocystis spp.