Use of next generation amplicon sequencing to study Blastocystis genetic diversity in a rural human population from Mexico

Authors: ROJAS-VELAZQUEZ, LILIANA - Universidad Nacional Autonoma De Mexico; Maloney, Jenny; MOLOKIN, ALEKSEY - Orise Fellow; MORAN, PATRICIA - Universidad Nacianal Autonoma De Mexico; VAZQUEZ-SERRANO, ANGELITA - Universidad Nacianal Autonoma De Mexico; GONZALEZ, ENRIQUE - Universidad Nacianal Autonoma De Mexico; PEREZ-JUAREZ, HORACIO - Universidad Nacianal Autonoma De Mexico; XIMENEZ, CECILIA - Universidad Nacianal Autonoma De Mexico; Santin-Duran, Monica

Submitted to: Parasites & Vectors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/19/2019
Publication Date: 11/27/2019
Citation: Rojas-Velazquez, L., Maloney, J.G., Molokin, A., Moran, P., Vazquez-Serrano, A., Gonzalez, E., Perez-Juarez, H., Ximenez, C., Santin, M. 2019. Use of next generation amplicon sequencing to study Blastocystis genetic diversity in a rural human population from Mexico. Parasites & Vectors. https://doi.org/10.1186/s13071-019-3814-z.
DOI: https://doi.org/10.1186/s13071-019-3814-z

Interpretive Summary: Blastocystis is a cosmopolitan enteric parasite found in humans and a wide range of animals across the world. It is spread through the consumption of contaminated food and water and has been associated with a variety of intestinal symptoms. Although Blastocystis is one of the most common parasites of humans, its prevalence and distribution in humans in North America is not well characterized. Molecular characterization to identify Blastocystis subtypes present in samples is critical to understand transmission, public health significance, and pathogenicity of this parasite. Mixed subtype infections are often overlooked in molecular studies of Blastocystis, and better characterization of these infections is needed to fully understand the parasite. Here we have applied next generation amplicon sequencing to a rural population from Mexico to better characterize Blastocystis prevalence, subtype distribution, and intra-host subtype diversity in humans. Of the 182 samples tested in this study, 68.1% (124) contained one or more Blastocystis subtypes. Subtype 3 was the most common subtype observed and was found in 81.5% of positive samples. Subtype 1, 16.9% of positive samples, and subtype 2, 17.7% of positive samples, were also found in this population. Mixed infections were observed in 13.7% of positive samples. In this population, the odds of having Blastocystis increased in adulthood (>15 years), and the odds of having subtype 1 increased in the presence of farm animals. The odds of having subtype 1, subtype 2, or a mixed infection decreased in the presence of cement flooring possibly indicating socioeconomic factors are involved in the risk of acquiring one of these subtypes. These data contribute to our understanding of the epidemiology of Blastocystis infections and can be used to shape future studies which aim to better characterize the transmission pathways and health outcomes of Blastocystis infections. This study provides beneficial information to other scientists, physicians, and public health agencies concerned with this widespread parasite.

Technical Abstract: The intestinal protist parasite Blastocystis is found in humans and animals around the world. It is spread through the consumption of contaminated food and water and has been associated with a variety of intestinal symptoms. Blastocystis is one of the most common parasites of humans, yet its prevalence and distribution in humans in North America is not well characterized. Here we have applied next generation amplicon sequencing of a region of the Blastocystis SSU rRNA gene to a rural population from Mexico to better characterize Blastocystis prevalence, subtype distribution, and intra-host subtype diversity in humans. Of the 182 samples tested in this study, 68.1% (124) contained one or more Blastocystis subtypes. Subtype 3 was the most common subtype observed and was found in 81.5% of positive samples. Subtype 1, 16.9% of positive samples, and subtype 2, 17.7% of positive samples, were also found in this population. Mixed infections were observed in 13.7% of positive samples. In this population, the odds of having Blastocystis increased in adulthood (>15 years), and the odds of having subtype 1 increased in the presence of farm animals. The odds of having subtype 1, subtype 2, or a mixed infection decreased in the presence of cement flooring possibly indicating socioeconomic factors are involved in the risk of acquiring one of these subtypes. These data contribute to our understanding of the epidemiology of Blastocystis infection in humans and can be used to shape future studies which aim to better characterize the transmission pathways and health outcomes of Blastocystis infections.