ORIGINAL PAPER Molecular identification of Ascaris lumbricoides and Ascaris suum recovered from humans and pigs in Thailand, Lao PDR, and Myanmar Lakkhana Sadaow 1 & Oranuch Sanpool 1,2 & Issarapong Phosuk 1 & Rutchanee Rodpai 1 & Tongjit Thanchomnang 2 & Adulsak Wijit 3 & Witthaya Anamnart 4 & Sakhone Laymanivong 1,5 & Win Pa Pa Aung 6 & Penchom Janwan 7 & Wanchai Maleewong 1 & Pewpan M. Intapan 1 Received: 23 March 2018 /Accepted: 15 May 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract Ascaris lumbricoides is the largest roundworm known from the human intestine while Ascaris suum is an internal parasite of pigs. Ascariasis, caused by Ascaris lumbricoides, has a worldwide distribution. Here, we have provided the first molecular identification of Ascaris eggs and adults recovered from humans and pigs in Thailand, Lao PDR, and Myanmar. We amplified and sequenced nuclear ribosomal DNA (ITS1 and ITS2 regions) and mitochondrial DNA (cox1 gene). Sequence chromatograms of PCR-amplified ITS1 region revealed a probable hybrid genotype from two human ascariasis cases from Chiang Mai Province, northern Thailand. All complete ITS2 sequences were identical and did not differ between the species. Phylogenetic trees and haplotype analysis of cox1 sequences showed three clusters with 99 haplotypes. Forty-seven samples from the present study represented 14 haplotypes, including 7 new haplotypes. To our knowledge, this is the first molecular confirmation of Ascaris species in Thailand, Lao PDR, and Myanmar. Zoonotic cross-transmission of Ascaris roundworm between pigs and humans probably occurs in these countries. Keywords Ascaris species . Pig . Human . Mitochondrial DNA . Nuclear ribosomal DNA . Molecular identification Introduction Ascaris lumbricoides is the largest nematode (roundworm) par- asitizing the human intestine and it is one of the principal soil- transmitted helminthic human infections worldwide, infecting an estimated 819 million people (Pullan et al. 2014; Holland 2013). Ascariasis has been considered as a neglected tropical disease by WHO and is highly prevalent in poor urban and rural areas (Dold and Holland 2010). Ascaris suum is an intestinal roundworm of pigs but can cause human ascariasis (Arizono et al. 2010). The two species are similar morphologically and closely related. Indeed, there is debate as to whether they are distinct species (Leles et al. 2012; Shao et al. 2014). Ascaris- infected pigs have been reported as a reservoir host for humans Section Editor: Xing-Quan Zhu Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00436-018-5931-6) contains supplementary material, which is available to authorized users. * Pewpan M. Intapan pewpan@kku.ac.th 1 Department of Parasitology, Faculty of Medicine and Research and Diagnostic Center for Emerging Infectious Disease, Mekong Health Science Research Institute, Khon Kaen University, Khon Kaen, Thailand 2 Faculty of Medicine, Maha Sarakham University, Maha Sarakham, Thailand 3 Office of Disease Prevention and Control, 1st, Department of Disease Control, Ministry of Public Health, Chiang Mai, Thailand 4 School of Public Health, Walailak University, Nakhon Si Thammarat, Thailand 5 Laboratory Unit, Centre of Malariology, Parasitology and Entomology, Ministry of Health, Vientiane, Lao People’ s Democratic Republic 6 Department of Microbiology, Ministry of Health and Sport, University of Medicine 2, Yangon, Myanmar 7 School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, Thailand Parasitology Research https://doi.org/10.1007/s00436-018-5931-6