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

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