Molecular Identification of Trichuris suis and Trichuris trichiura Eggs in Human Populations from Thailand, Lao PDR, and Myanmar

Abstract

<i>Trichuris trichiura</i> is a soil-transmitted helminth infecting human populations globally. Human cases caused by <i>Trichuris suis</i> and <i>Trichuris vulpis</i> have also been reported. Molecular identifications of <i>Trichuris</i> species infecting human populations in Lao PDR and Myanmar are lacking. Here, we explored molecular data obtained from <i>Trichuris</i> eggs recovered from human fecal samples from these countries and compared these with new and existing data from Thailand. Nuclear ribosomal DNA (18S and ITS2) sequences were amplified from <i>Trichuris</i> eggs and sequenced. Forty-one samples showed 99-100% similarity in their 18S sequences to published sequences of <i>T. trichiura</i> and one sample showed 99% similarity to a sequence of <i>T. suis</i>. Similarly, 41 samples showed 92-100% similarity in their ITS2 sequences to published sequences of <i>T. trichiura</i> and one sample showed 94-97% similarity to sequences of <i>T. suis</i>. This study is the first molecular confirmation of human infection with <i>T. suis</i> in northeast Thailand and the first molecular confirmation of the species of <i>Trichuris</i> infecting humans in Lao PDR and Myanmar.