Abstract
Strongyloidiasis is a major soil-transmitted helminth (STH) disease that affects people worldwide. We present updated data on prevalence in the Lao People’s Democratic Republic (Lao PDR) in 2015, arising from a community cross-sectional helminthiasis survey. Fecal samples were collected from 327 individuals across three provinces in Lao PDR (Luang Prabang in the north, Khammouane in the center, and Champasack in the south). Agar plate culture and Kato-Katz methods were used to examine duplicate stool samples from each participant to detect Strongyloides stercoralis and co-infecting helminths. Overall prevalences of S. strercoralis human hookworm, Taenia spp., Trichuris trichiura, Ascaris lumbricoides, and Enterobius vermicularis were 41.0, 28.1, 4.9, 4.0, 1.5, and 0.9 %, respectively. The prevalence of miscellaneous trematodiases (including opisthorchiasis) was 37.9 % and of Schistosoma mekongi infection was 0.3 %. Strongyloidiasis is a current major STH disease in Lao PDR. We also report the molecular-phylogenetic identification of S. stercoralis adult males collected from 40 representative human strongyliodiasis fecal samples. DNA was extracted, amplified, and sequenced from a portion of the mitochondrial cox1 gene and the nuclear 18S ribosomal DNA. Phylogenetic analyses indicated that all specimens sequenced belonged to S. stercoralis (Bavay, 1876) Stiles and Hassall, 1902. The cox1 sequences exhibited great diversity (24 haplotypes) in Lao PDR. This is the first molecular identification and report of genetic diversity of S. stercoralis in humans from Lao PDR. An effective parasite control program is needed to reduce the serious health impacts.
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Acknowledgments
We would like to thank David Blair for his valuable suggestions and assistance with the presentation of this paper through Khon Kaen University Publication Clinic. This study was supported by a TRF Senior Research Scholar Grant, Thailand Research Fund grant number RTA5880001; the Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission, Thailand, through the Health Cluster (SHeP-GMS); the Faculty of Medicine, Khon Kaen University (TR57201) through WM and PM. SL was partial supported by the Faculty of Medicine, Khon Kaen University (IN59110). JJ and OS were supported by Post-Doctoral Training Program of Graduate School and Khon Kaen University.
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The study protocol was approved by the Lao National Ethics Committee for Health Research, Ministry of Health, Laos (no. 056/2015) and by the Khon Kaen University Ethics Committee for Human Research (HE581292). Each participant was informed of the study methods, risks, and benefits of the process. Before enrolment, written consent was obtained from all adult participants and from parents or legal guardians of minors.
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Laymanivong, S., Hangvanthong, B., Insisiengmay, B. et al. First molecular identification and report of genetic diversity of Strongyloides stercoralis, a current major soil-transmitted helminth in humans from Lao People’s Democratic Republic. Parasitol Res 115, 2973–2980 (2016). https://doi.org/10.1007/s00436-016-5052-z
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DOI: https://doi.org/10.1007/s00436-016-5052-z