Angiostrongylus cantonensis is a zoonotic nematode parasite causing human eosinophilic meningitis (or meningoencephalitis) worldwide. A closely related species, Angiostrongylus malaysiensis, might also be a human pathogen. Larvae were obtained from land snails in Lao PDR, Cambodia, Myanmar and Thailand. We sequenced two nuclear gene regions (nuclear ribosomal ITS2 and SSU rRNA) and a portion of one mitochondrial gene (COI) from these larvae. Angiostrongylus cantonensis and A. malaysiensis were identified. This is the first report of the molecular identification of the two Angiostrongylus species in Lao PDR, Cambodia and Myanmar. The regional distributions of the two species broadly overlap. Phylogenetic relationships were inferred including data from Angiostrongylus species deposited in public databases. All the gene regions we sequenced have potential value in distinguishing between species of Angiostrongylus. The COI gene exhibited the greatest intraspecific variation in the study region (five haplotypes in A. cantonensis and four in A. malaysiensis) and might be suitable for more detailed phylogeographic studies.
The parasitic nematodes, Strongyloides stercoralis and Strongyloides fuelleborni, can infect humans and non-human primates. We amplified and sequenced a portion of the 18S ribosomal RNA gene (rRNA) and of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene of Strongyloides from humans in the study area in Thailand, where people have frequent contact with long-tailed macaques. Fresh stool samples were obtained from 213 people and were examined using the agar plate culture method. The overall prevalence of Strongyloides infection was 8.92% (19/213). From a total of 19 worms (one per infected person), 18 adult males had 18S rRNA sequences identical with that of S. stercoralis and one adult female had a sequence almost identical with that of S. fuelleborni. A median-joining network of cox1 sequences revealed nine new haplotypes from S. stercoralis, and an overall haplotype diversity (Hd) of 0.9309. The single haplotype of S. fuelleborni was also new and contributed to an overall haplotype diversity for that species of 0.9842. This is the first molecular identification of S. stercoralis and S. fuelleborni in a human community having contact with long-tailed macaques in Thailand. It is also the first report of S. fuelleborni infecting a human in Thailand.
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.
Human opisthorchiasis caused by the liver fluke Opisthorchis viverrini is an endemic disease in Southeast Asian countries including the Lao People's Democratic Republic, Cambodia, Vietnam, and Thailand. Infection with the soil-transmitted roundworm Strongyloides stercoralis is an important problem worldwide. In some areas, both parasitic infections are reported as co-infections. A duplex real-time fluorescence resonance energy transfer (FRET) PCR merged with melting curve analysis was developed for the rapid detection of O. viverrini and S. stercoralis in human fecal samples. Duplex real-time FRET PCR is based on fluorescence melting curve analysis of a hybrid of amplicons generated from two genera of DNA elements: the 162 bp pOV-A6 DNA sequence specific to O. viverrini and the 244 bp 18S rRNA sequence specific to S. stercoralis, and two pairs of specific fluorophore-labeled probes. Both O. viverrini and S. stercoralis can be differentially detected in infected human fecal samples by this process through their different fluorescence channels and melting temperatures. Detection limit of the method was as little as two O. viverrini eggs and four S. stercoralis larvae in 100 mg of fecal sample. The assay could distinguish the DNA of both parasites from the DNA of negative fecal samples and fecal samples with other parasite materials, as well as from the DNA of human leukocytes and other control parasites. The technique showed 100% sensitivity and specificity. The introduced duplex real-time FRET PCR can reduce labor time and reagent costs and is not prone to carry over contamination. The method is important for simultaneous detection especially in areas where both parasites overlap incidence and is useful as the screening tool in the returning travelers and immigrants to industrialized countries where number of samples in the diagnostic units will become increasing.
Abstract. Human trichostrongylosis has been reported in Thailand. Recent reports in Lao People's Democratic Republic concerning species identification urged us to investigate species distribution in Thailand. We report eight human cases in Thailand and Lao People's Democratic Republic that were found to be infected by Trichostrongylus colubriformis and T. axei identified and confirmed by molecular techniques. This evidence is the first molecular evidence of human T. colubriformis and T. axei infection in Thailand. Infection by these two species was apparently epidemic in these areas. It is necessary to proceed with more comprehensive veterinary and epidemiologic studies to enable the practical prevention and control of this parasitic zoonosis.
The 2 principal species of hookworms infecting humans are Necator americanus and Ancylostoma duodenale. Case studies on zoonotic hookworm infections with Ancylostoma ceylanicum and/or Ancylostoma caninum are known mainly from Asian countries. Of these 2 zoonotic species, only A. ceylanicum can develop to adulthood in humans. In the present study, we report a molecular-based survey of human hookworm infections present in southern and northeastern Thailand. Thirty larval hookworm samples were obtained from fecal agar plate cultures of 10 patients in northeastren Thailand and 20 in southern Thailand. Partial ITS1, 5.8S, and ITS2 regions of the ribosomal DNA genes were amplified using PCR. The amplicons were sequenced, aligned, and compared with other hookworm sequences in GenBank database. The results showed that, in Thailand, N. americanus is more prevalent than Ancylostoma spp. and is found in both study areas. Sporadic cases of A. ceylanicum and A. duodenale infection were seen in northeastern Thailand.
BackgroundTwo important helminths, Strongyloides stercoralis (an intestinal roundworm) and Opisthorchis viverrini (a liver fluke), are endemic in northeast Thailand. There have been national campaigns in place aimed at the control and eradication of soil-transmitted helminthiasis and opisthorchiasis in Thailand for several decades. However, these helminths still exist and raise concerns regarding public health. This study aimed to evaluate the current prevalence of S. stercoralis and O. viverrini infections in rural communities in northeast Thailand. The data from this study will be useful to improve strategies for future helminth prevention and control.MethodsA cross-sectional study was conducted from December 2016 to June 2017 in Mueang Khon Kaen district in Khon Kaen, Thailand. The participants were selected using a simple random sampling method. Demographic data were collected using a questionnaire. Stool samples were collected and processed using agar plate culture to determine the presence of S. stercoralis infection and an in-house formalin-ethyl acetate concentration technique to determine the presence of O. viverrini and other intestinal parasite infections (IPIs).ResultsIn total, 602 persons were enrolled. However, only 526 were analyzed for S. stercoralis and 387 for O. viverrini risk factors. The overall prevalence of S. stercoralis infection was 23.0% (95% confidence interval [95%CI]: 19.4 to 26.6). The prevalence of O. viverrini infection and IPIs other than S. stercoralis was 20.4% (95%CI: 16.5 to 24.8). The prevalence of O. viverrini infection was 19.4% (95%CI: 15.6 to 23.7). Male sex was significantly associated with S. stercoralis infection [Adjusted Odds Ratio (aOR) 4.0; 95%CI: 2.5 to 6.2; P-value < 0.001]. Males were significantly more likely to be infected with O. viverrini and other IPIs (aOR 4.1; 95%CI: 2.3 to 7.2, P-value < 0.001).ConclusionsThis study demonstrated that the updated prevalence of intestinal parasite infections is still high in rural communities in northeast Thailand, especially that of strongyloidiasis and opisthorchiasis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.