Epidemiological aspects of blastocystis colonization in children in Ilero, Nigeria

This study aimed to elucidate aspects of the epidemiology of Blastocystis in Nigerian school children, including the distribution of subtypes (STs) and ST alleles. A total of 199 genomic DNAs extracted from fecal samples from 199 Nigerian children aged 2-14 years were tested by real-time polymerase chain reaction for Blastocystis. Positive DNAs were submitted to barcoding by PCR and sequencing to obtain information on STs and ST alleles. A total of 167 (84%) samples were positive for Blastocystis, with prevalence increasing by age. No association between Blastocystis colonization and gender (P = 0.51) or type/presence of toilet facilities (P = 0.21) was observed. Blastocystis carriers were more prone to using water collected from wells than from sachets (P = 0.0044). Moreover, Blastocystis positivity was associated with positivity for fecal-orally transmitted protozoa (P = 0.018) and helminths (P < 0.0001). A clear inverse association of Blastocystis colonization and malaria infection was observed (P < 0.0001); however, malaria-positive children being younger than malaria-negative children, this finding was attributed to the age effect of Blastocystis colonization. ST data were available for 127/167 (76%) samples. Fifty-one children were positive for ST1, while 42 and 33 children were colonized with ST2 and ST3, respectively; a single case of ST7 was observed. By and large, the ST alleles identified for ST1 and ST2 did not differ from those observed in humans in other regions of the world; meanwhile, the distribution of ST3 alleles was remarkably distinct and potentially specific to humans in sub-Saharan Africa.