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1.
PLoS One ; 17(3): e0264766, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35259176

RESUMO

Human gnathostomiasis is a food-borne zoonotic helminthic infection widely reported in Latin America, Asia and Southeast Asia, particularly in Thailand. There are increasing reports of the parasite in countries where it is not endemic. A study of the survival drug-treated immature stage (STIM) of Gnathostoma spinigerum recovered from infected patients focused on their integument surface using scanning electron microscopy (SEM). STIM displayed a specific, characteristic head bulb, with a pair of large thick equal-sized trilobulated lips in the centre. Cephalic spines had eight transverse rows on the head bulb with single-ended tips curved posteriorly. Body cuticular spines on the anterior half of the STIM were not sharp-pointed but distributed more densely, with multi-dentated-cuticular spines, irregularly arranged in a lining pattern of velvety cuticular folds. The length of cuticular spines increased caudally. The size of spines became gradually smaller, and numbers decreased towards the posterior end. Spines were still widely dispersed posteriorly as their density dropped. The morphology of STIM of G. spinigerum are described in detail for the first time. These specimens showed structural adaptation based on changes on integument surfaces, probably to protect against damage induced by the toxic effects of albendazole.


Assuntos
Gnathostoma , Albendazol/uso terapêutico , Animais , Humanos , Larva , Microscopia Eletrônica de Varredura , Tailândia
2.
BMC Genomics ; 23(1): 104, 2022 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-35130837

RESUMO

BACKGROUND: Genetic markers like the nuclear ribosomal RNA (rRNA) genes, internal transcribed spacer regions, mitochondrial protein-coding genes, and genomes have been utilized for molecular identification of parasitic trematodes. However, challenges such as the design of broadly applicable primers for the vast number of species within Digenea and the genetic markers' ability to provide sufficient species-level resolution limited their utility. This study presented novel and broadly applicable primers using the mitochondrial 12S and 16S rRNA genes for Digenea and aimed to show their suitability as alternative genetic markers for molecular identification of orders Plagiorchiida, Echinostomida, and Strigeida. RESULTS: Our results revealed that the mitochondrial 12S and 16S rRNA genes are suitable for trematode molecular identification, with sufficient resolution to discriminate closely related species and achieve accurate species identification through phylogenetic placements. Moreover, the robustness of our newly designed primers to amplify medically important parasitic trematodes encompassing three orders was demonstrated through successful amplification. The convenience and applicability of the newly designed primers and adequate genetic variation of the mitochondrial rRNA genes can be useful as complementary markers for trematode molecular-based studies. CONCLUSIONS: We demonstrated that the mitochondrial rRNA genes could be alternative genetic markers robust for trematode molecular identification and potentially helpful for DNA barcoding where our primers can be widely applied across the major Digenea orders. Furthermore, the potential of the mitochondrial rRNA genes for molecular systematics can be explored, enhancing their appeal for trematode molecular-based studies. The novelty of utilizing the mitochondrial rRNA genes and the designed primers in this study can potentially open avenues for species identification, discovery, and systematics in the future.


Assuntos
Código de Barras de DNA Taxonômico , Trematódeos , Animais , DNA Mitocondrial/genética , DNA Ribossômico , Genes Mitocondriais , Filogenia , RNA Ribossômico , RNA Ribossômico 16S/genética , Trematódeos/genética
3.
Parasit Vectors ; 14(1): 496, 2021 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-34565456

RESUMO

BACKGROUND: The malaria vector Anopheles minimus has been influenced by external stresses affecting the survival rate and vectorial capacity of the population. Since An. minimus habitats have continuously undergone ecological changes, this study aimed to determine the population genetic structure and the potential gene flow among the An. minimus populations in Thailand. METHODS: Anopheles minimus was collected from five malaria transmission areas in Thailand using Centers for Disease Control and Prevention (CDC) light traps. Seventy-nine females from those populations were used as representative samples. The partial mitochondrial cytochrome c oxidase subunit I (COI), cytochrome c oxidase subunit II (COII) and cytochrome b (Cytb) gene sequences were amplified and analyzed to identify species and determine the current population genetic structure. For the past population, we determined the population genetic structure from the 60 deposited COII sequences in GenBank of An. minimus collected from Thailand 20 years ago. RESULTS: The current populations of An. minimus were genetically divided into two lineages, A and B. Lineage A has high haplotype diversity under gene flow similar to the population in the past. Neutrality tests suggested population expansion of An. minimus, with the detection of abundant rare mutations in all populations, which tend to arise from negative selection. CONCLUSIONS: This study revealed that the population genetic structure of An. minimus lineage A was similar between the past and present populations, indicating high adaptability of the species. There was substantial gene flow between the eastern and western An. minimus populations without detection of significant gene flow barriers.


Assuntos
Anopheles/genética , Proteínas de Insetos/genética , Malária/transmissão , Mitocôndrias/genética , Mosquitos Vetores/genética , Animais , Anopheles/classificação , Anopheles/fisiologia , Citocromos b/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Fluxo Gênico , Marcadores Genéticos , Mosquitos Vetores/classificação , Mosquitos Vetores/fisiologia , Filogenia , Tailândia
4.
Food Waterborne Parasitol ; 24: e00128, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34458598

RESUMO

Angiostrongylus cantonensis, the main causative agent of human neuroangiostrongyliasis, is a food-borne parasitic zoonosis, particularly in Southeast Asia and Mainland China. Angiostrongylus malaysiensis, a cryptic species, has not been unequivocally identified as a causative agent for human angiostrongyliasis. Here, we investigated a local incidence of human angiostrongyliasis in Kalasin Province, northeastern part of Thailand. Field and laboratory investigations, clinical symptoms, and treatment of the disease are also discussed. Five sera and three cerebrospinal fluid samples were taken from each patient who displayed clinical symptoms of mild or severe headache without neck stiffness after ingesting a local dish containing Pila virescens. With molecular evidence using PCR and DNA sequencing approaches, we confirmed the presence of A. malaysiensis and A. cantonensis DNA in the patient samples. In addition, P. virescens and Pomacea canaliculata collected in the vicinity were also examined for the existence of angistrongylid larvae. The rate of infection in the snail population was 33.3% (18 infection out of 54 examined), with A. cantonensis as the predominant species. Notably, two snails were found to be co-infected with both A. malaysiensis and A. cantonensis. This discovery comes after several years of suspicion that it could be a zoonotic pathogen. Therefore, our findings are important for public health and clinical diagnosis since clinicians are not aware of the zoonotic potential of A. malaysiensis in humans.

5.
Parasit Vectors ; 14(1): 233, 2021 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933158

RESUMO

BACKGROUND: Genetic markers are employed widely in molecular studies, and their utility depends on the degree of sequence variation, which dictates the type of application for which they are suited. Consequently, the suitability of a genetic marker for any specific application is complicated by its properties and usage across studies. To provide a yardstick for future users, in this study we assess the suitability of genetic markers for molecular systematics and species identification in helminths and provide an estimate of the cut-off genetic distances per taxonomic level. METHODS: We assessed four classes of genetic markers, namely nuclear ribosomal internal transcribed spacers, nuclear rRNA, mitochondrial rRNA and mitochondrial protein-coding genes, based on certain properties that are important for species identification and molecular systematics. For molecular identification, these properties are inter-species sequence variation; length of reference sequences; easy alignment of sequences; and easy to design universal primers. For molecular systematics, the properties are: average genetic distance from order/suborder to species level; the number of monophyletic clades at the order/suborder level; length of reference sequences; easy alignment of sequences; easy to design universal primers; and absence of nucleotide substitution saturation. Estimation of the cut-off genetic distances was performed using the 'K-means' clustering algorithm. RESULTS: The nuclear rRNA genes exhibited the lowest sequence variation, whereas the mitochondrial genes exhibited relatively higher variation across the three groups of helminths. Also, the nuclear and mitochondrial rRNA genes were the best possible genetic markers for helminth molecular systematics, whereas the mitochondrial protein-coding and rRNA genes were suitable for molecular identification. We also revealed that a general gauge of genetic distances might not be adequate, using evidence from the wide range of genetic distances among nematodes. CONCLUSION: This study assessed the suitability of DNA genetic markers for application in molecular systematics and molecular identification of helminths. We provide a novel way of analyzing genetic distances to generate suitable cut-off values for each taxonomic level using the 'K-means' clustering algorithm. The estimated cut-off genetic distance values, together with the summary of the utility and limitations of each class of genetic markers, are useful information that can benefit researchers conducting molecular studies on helminths.


Assuntos
Classificação , Marcadores Genéticos , Helmintos/classificação , Animais , DNA Mitocondrial/análise , Helmintos/genética , Helmintos/isolamento & purificação , Patologia Molecular , RNA Ribossômico/análise
6.
Food Waterborne Parasitol ; 23: e00119, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33817357

RESUMO

Angiostrongylus cantonensis is a well-known pathogen causing eosinophilic meningitis associated with angiostrongyliasis. Humans, as accidental hosts, are infected by consuming undercooked snails containing third-stage larvae. A. malaysiensis is closely related to A. cantonensis and has been described as a potential human pathogen. The two species distribution was recently reported to overlap in the same endemic area, particularly in the Indochina Peninsula. Similar morphological characteristics of the third-stage larva in the snail-intermediate host often lead to misidentification of the two species. Thus, we aimed to develop a sensitive and specific method to detect and discriminate Angiostrongylus third-stage larva by designing species-specific primers based on the mitochondrial cytochrome b gene. We developed the SYBR Green quantitative real-time PCR (qPCR) method for two species-specific detection assays, which could be conducted simultaneously. The method was subsequently employed to detect and identify third-stage larvae of Angiostrongylus isolated from infected Achatina fulica collected from six public parks in Bangkok Metropolitan, Thailand. The method was also a preliminary applied to detect parasite tissue debris in the patients' cerebrospinal fluid (CSF). SYBR Green qPCRs quantitatively detected approximately 10-4 ng of genomic DNA from one larva, facilitating species-specific detection. Based on the pools of third-stage larvae isolated individually from the tissue of each infected A. fulica collected from the public parks, the qPCR results revealed that A. malaysiensis was the predominant species infecting 5.26% of the collected snails. In comparison, coinfection between A. malaysiensis and A. cantonensis was 5.97%, and no single infection of A. cantonensis was detected in A. fulica. Our SYBR Green qPCR method is a useful and inexpensive technique for A. cantonensis and A. malaysiensis discrimination, and the method has sufficient sensitivity to detect isolated larvae from a snail-intermediate host. The ratio of A. cantonensis and A. malaysiensis larvae infecting the snails can also be estimated simultaneously. Our qPCRs can be employed in a molecular survey of A. cantonensis and A. malaysiensis within intermediate hosts and for clinical diagnosis of angiostrongyliasis with CSF specimens in future studies.

7.
Parasitol Res ; 119(11): 3675-3690, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33001253

RESUMO

In 2018, extensive field studies of diversity and prevalence of helminth infection in synanthropic rodents and non-rodent small mammals from public parks and citified areas in the Bangkok Metropolitan were conducted. Rattus rattus complex was the dominant small mammal in public parks. Of the 197 animals, 147 individuals were infected with one or more species of helminths, yielding an infection prevalence of 74.6%. Twenty-five species of helminths were recovered during necropsy. Pterygodermatites tani was the most prevalent (36.2%); other encountered species included Raillietina celebensis, Hydatigera taeniaformis (metacestode in liver tissue), Gongylonema neoplasticum and Hymenolepis diminuta. Different helminth assemblages infected three different host taxa, i.e. synanthropic Rattus spp., Tupaia belangeri (Northern treeshrew) and Suncus murinus (Asian house shrew). Nine species of possible zoonotic helminths were identified. The focus on synanthropic rats influenced the findings of helminth diversity by either host intrinsic or extrinsic factors. A significant positive correlation was found between host body mass and helminth species richness. Greater helminth species richness was found in rats from public parks compared with animals from citified areas (e.g. inside buildings or offices). Also, helminth species richness was negatively correlated with the proportion of post-flooding/rain-fed land. These results provide essential information for assessing the incidence of potential zoonotic health threats in Bangkok and updating research in parasite ecology.


Assuntos
Biota , Helmintíase Animal/parasitologia , Helmintos/classificação , Doenças dos Roedores/parasitologia , Roedores/parasitologia , Animais , Cidades , Inundações , Helmintíase Animal/epidemiologia , Helmintos/isolamento & purificação , Humanos , Parques Recreativos , Prevalência , Ratos , Doenças dos Roedores/epidemiologia , Musaranhos/parasitologia , Tailândia/epidemiologia
8.
Acta Trop ; 211: 105645, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32702297

RESUMO

The Angiostrongylus cantonensis lineage (Nematoda: Metastrongyloidea) consists of the closely related species A. cantonensis, Angiostrongylus malaysiensis, and Angiostrongylus mackerrasae. Various genetic markers have been used for species discrimination in molecular phylogenetic studies of this lineage. However, despite showing potential in other organisms, mitochondrial 12S and 16S ribosomal RNA (rRNA) genes have not been used for Angiostrongylus species discrimination. Therefore, this study assessed these genes' suitability for inter- and intraspecies discrimination in the A. cantonensis lineage. The ultimate aim was to provide a novel genetic marker to support existing phylogenies. Sixty adult Angiostrongylus spp. worms from four geographic locations in Thailand were identified morphologically before molecular identification with 12S and 16S rRNA genes. Neighbor-joining and maximum likelihood algorithms were used for phylogenetic analyzes, and sequence variation was calculated to determine whether the genes could be used to discriminate among species. Furthermore, sequence variation was compared among previously used genetic markers to evaluate the robustness of the 12S and 16S rRNA genes as markers. Using both markers, the A. cantonensis lineage formed a monophyletic clade with a clear separation between A. cantonensis, A. malaysiensis, and A. mackerrasae. From our representative A. cantonensis and A. malaysiensis specimens, the genetic distance between the two clades was 6.8% -7.9% and 7.9% -10.0% for 12S and 16S rRNA genes, respectively, which is sufficient interspecific genetic variation for species discrimination. Higher levels of genetic variation were observed for the 16S rRNA gene, with 12 haplotypes and an intraspecific variation ≤2.2%. Thus, as a genetic marker, the 16S rRNA gene is comparable to mitochondrial protein-coding genes, which are commonly used in intra-level Angiostrongylus spp. studies. In conclusion, mitochondrial 12S and 16S rRNA genes can discriminate among closely related species in the A. cantonensis lineage, and they represent novel genetic markers for supporting existing phylogenies and verifying the phylogenetic position of A. mackerrasae.


Assuntos
Angiostrongylus cantonensis/genética , Genes Mitocondriais , Marcadores Genéticos , Filogenia , Animais , Haplótipos , RNA Ribossômico 16S/genética
9.
Parasit Vectors ; 13(1): 364, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32690073

RESUMO

BACKGROUND: Molecular advances have accelerated our understanding of nematode systematics and taxonomy. However, comparative analyzes between various genetic markers have led to discrepancies in nematode phylogenies. This study aimed to evaluate the suitability of using mitochondrial 12S and 16S ribosomal RNA genes for nematode molecular systematics. METHODS: To study the suitability of mitochondrial 12S and 16S ribosomal RNA genes as genetic markers for nematode molecular systematics, we compared them with the other commonly used genetic markers, nuclear internal transcribed spacer 1 and 2 regions, nuclear 18S and 28S ribosomal RNA genes, and mitochondrial cytochrome c oxidase subunit 1 gene. After that, phylum-wide primers for mitochondrial 12S and 16S ribosomal RNA genes were designed, and parasitic nematodes of humans and animals from 75 taxa with 21 representative species were inferred through phylogenetic analyzes. Phylogenetic analyzes were carried out using maximum likelihood and Bayesian inference algorithms. RESULTS: The phylogenetic relationships of nematodes based on the mitochondrial 12S rRNA gene supported the monophyly of nematodes in clades I, IV, and V, reinforcing the potential of this gene as a genetic marker for nematode systematics. In contrast, the mitochondrial 16S rRNA gene only supported the monophyly of clades I and V, providing evidence that the 12S rRNA gene is more suitable for nematode molecular systematics. In this study, subclades of clade III containing various nematode families were not monophyletic when the 16S or 12S rRNA gene was used as the genetic marker. This is similar to the phylogenetic relationship revealed by previous studies using whole mitochondrial genomes as genetic markers. CONCLUSIONS: This study supports the use of the 12S rRNA gene as a genetic marker for studying the molecular systematics of nematodes to understand intra-phyla relationships. Phylum-wide primers for nematodes using mitochondrial ribosomal genes were prepared, which may enhance future studies. Furthermore, sufficient genetic variation in the mitochondrial 12S and 16S rRNA genes between species also allowed for accurate taxonomy to species level, revealing the potential of these two genes as genetic markers for DNA barcoding.


Assuntos
Código de Barras de DNA Taxonômico/métodos , Genes Mitocondriais , Nematoides , Animais , Classificação , Marcadores Genéticos , Genoma Mitocondrial , Humanos , Nematoides/classificação , Nematoides/genética , Parasitos/classificação , Parasitos/genética , Filogenia , RNA Ribossômico/genética , RNA Ribossômico 16S/genética
10.
PeerJ ; 8: e8597, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32117632

RESUMO

BACKGROUND: Fasciola hepatica and F. gigantica cause fascioliasis in both humans and livestock. Some adult specimens of Fasciola sp. referred to as "intermediate forms" based on their genetic traits, are also frequently reported. Simple morphological criteria are unreliable for their specific identification. In previous studies, promising phenotypic identification scores were obtained using morphometrics based on linear measurements (distances, angles, curves) between anatomical features. Such an approach is commonly termed "traditional" morphometrics, as opposed to "modern" morphometrics, which is based on the coordinates of anatomical points. METHODS: Here, we explored the possible improvements that modern methods of morphometrics, including landmark-based and outline-based approaches, could bring to solving the problem of the non-molecular identification of these parasites. F. gigantica and Fasciola intermediate forms suitable for morphometric characterization were selected from Thai strains following their molecular identification. Specimens of F. hepatica were obtained from the Liverpool School of Tropical Medicine (UK). Using these three taxa, we tested the taxonomic signal embedded in traditional linear measurements versus the coordinates of anatomical points (landmark- and outline-based approaches). Various statistical techniques of validated reclassification were used, based on either the shortest Mahalanobis distance, the maximum likelihood, or the artificial neural network method. RESULTS: Our results revealed that both traditional and modern morphometric approaches can help in the morphological identification of Fasciola sp. We showed that the accuracy of the traditional approach could be improved by selecting a subset of characters among the most contributive ones. The influence of size on discrimination by shape was much more important in traditional than in modern analyses. In our study, the modern approach provided different results according to the type of data: satisfactory when using pseudolandmarks (outlines), less satisfactory when using landmarks. The different reclassification methods provided approximately similar scores, with a special mention to the neural network, which allowed improvements in accuracy by combining data from both morphometric approaches. CONCLUSION: We conclude that morphometrics, whether traditional or modern, represent a valuable tool to assist in Fasciola species recognition. The general level of accuracy is comparable among the various methods, but their demands on skills and time differ. Based on the outline method, our study could provide the first description of the shape differences between species, highlighting the more globular contours of the intermediate forms.

11.
Evol Appl ; 11(8): 1257-1269, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30151038

RESUMO

Angiostrongylus cantonensis, the rat lungworm, is a zoonotic pathogen that is one of the leading causes of eosinophilic meningitis worldwide. This parasite is regarded as an emerging pathogen with a global range expansion out of southeastern Asia post-WWII. To date, molecular systematic/phylogeographic studies on A. cantonensis have mainly used two mitochondrial (mtDNA) markers, cytochrome c oxidase 1 (CO1) and cytochrome b (CYTB), where the focus has largely been descriptive in terms of reporting local patterns of haplotype variants. In order to look for more global evolutionary patterns, we herein provide a collective phylogenetic assessment using the six available whole mtDNA genome samples that have been tagged as A. cantonensis, A. malaysiensis, or A. mackerrasae along with all other GenBank CO1 and CYTB partial sequences that carry these species identifiers. The results reveal three important complications that researchers will need to be aware of, or will need to resolve, prior to conducting future molecular evolutionary studies on A. cantonensis. These three problems are (i) incongruence between taxonomic identifications and mtDNA variants (haplotypes or whole mtDNA genome samples), (ii) the presence of a CYTB mtDNA pseudogene, and (iii) the need to verify A. mackerrasae as a species along with other possible cryptic lineages, of which there is suggestive evidence (i.e., A. cantonensis could be a species complex). We provided a discussion of how these complications are hurdles to our understanding of the global epidemiology of angiostrongyliasis. We call for future studies to be more explicit in morphological traits used for identifications (e.g., provide measurements). Moreover, it will be necessary to repeat prior morphological and life-history studies while simultaneously using sequence data in order to assess possible associations between critical epidemiological data (e.g., biogeography, virulence/pathology, host species use) and specific lineages.

12.
Artigo em Inglês | MEDLINE | ID: mdl-29644815

RESUMO

Taenia solium, T. saginata, and T. asiatica are cestode pathogens causing taeniasis in humans. Houseflies can transfer Taenia eggs to food. However, houseflies are thought to carry only small numbers of Taenia eggs, sometimes fewer than 10. Although several PCR-based methods have been developed to detect Taenia DNA, these require more than 10 eggs for adequate detection. We developed a multiplex PCR method with high specificity for the discrimination among the eggs of the three Taenia species, T. solium, T. saginata, and T. asiatica, using 18S ribosomal DNA (rDNA) as a genetic marker. This technique was found to be highly sensitive, capable of identifying the Taenia species from only one egg. This multiplex PCR technique using 18S rDNA specific primers should be suitable to diagnose Taenia eggs.


Assuntos
Moscas Domésticas/parasitologia , Reação em Cadeia da Polimerase Multiplex/métodos , Óvulo/classificação , Taenia/isolamento & purificação , Animais , DNA de Helmintos/genética , Marcadores Genéticos , Humanos , RNA de Helmintos/genética , RNA Ribossômico 18S/genética , Sensibilidade e Especificidade
13.
Mol Phylogenet Evol ; 107: 404-414, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27940331

RESUMO

Delimitation of species is still a necessity among parasitic pathogens especially where morphological characters provide limited discernibility. Identification of cryptic lineages (independently evolving lineages that are morphologically similar) is critical as there could be lineage-specific traits that are of epidemiological importance. Angiostrongylus cantonensis is a zoonotic pathogen that can cause eosinophilic meningitis in humans. Recent reports of single marker sequence divergence hint at the potential for cryptic diversity in this lungworm. However, to definitively address if single marker divergence corresponds to independent evolving lineages, a multilocus approach is necessary. Using multilocus data, our goal was to determine if there were cryptic lineages within Thailand, a country plagued by several outbreaks and isolated cases of A. cantonensis infection. We analyzed the genetic structure of A. cantonensis samples collected from snails, Achatina fulica, across provinces in Thailand. Multilocus data (mitochondrial sequence data and 12 nuclear microsatellites) and individual based analyses were used to test for cryptic lineages. We found strong linkage disequilibrium patterns between mitochondrial haplotypes and nuclear-identified genetic clusters. There were clearly two divergent and independent clades. Moreover, within each clade, the data suggested additional substructure where individual provinces were likely to harbor unique genetic clusters. The results indicate there are at minimum two and possibly up to eight cryptic lineages within the assumed single species of A. cantonensis. Importantly, the two main clades do not show geographic affiliation and can be found in sympatry. With recent studies highlighting A. cantonensis strain diversity in pathogenicity and infectivity, it will be important to determine if these critical epidemiological traits are associated with specific lineages.


Assuntos
Angiostrongylus cantonensis/classificação , Angiostrongylus cantonensis/genética , Variação Genética , Filogenia , Zoonoses/parasitologia , Animais , Teorema de Bayes , Citocromos b/genética , DNA Mitocondrial/genética , Geografia , Haplótipos/genética , Humanos , Repetições de Microssatélites/genética , Família Multigênica , Tailândia
14.
Parasitol Res ; 115(3): 1123-30, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26614357

RESUMO

Metagonimus Katsurada, 1912 is a genus of small intestinal parasites. The genus comprises eight species, primarily from far-eastern Asia, with two exceptions reported from Europe. Metagonimus yokogawai, the most widespread species, is the main agent responsible for the intestinal disease, metagonimiasis, in Japan and some other East Asian countries. On the basis of the ratio of the size of the ventral and oral suckers, Metagonimus has traditionally been morphologically divided into two groups; however, the genus has not been extensively studied using molecular data. To reveal phylogenetic relationships within Metagonimus based on molecular data, we analyzed six of the seven species present in Asia using samples collected in central Japan. Maximum likelihood and Bayesian analyses of a combined 28S ribosomal DNA (rDNA), internal transcribed spacer 2 (ITS2), and mitochondrial cox1 gene sequence dataset separated the six species into two well-supported clades. One clade comprised M. yokogawai, M. takahashii, M. miyatai, and M. hakubaensis, whereas the other consisted of M. otsurui and M. katsuradai. Genetic distances calculated from 28S rDNA and ITS2 nucleotide sequences and a comparison of the predicted amino acid sequences of cox1 gene suggested that M. otsurui and M. katsuradai may have diverged recently. None of the four main morphological characters used to delimit species of Metagonimus (i.e., sucker ratio, positions of the uterus and testes, and distribution of vitelline follicles) was consistent with the distribution of species in the molecular tree.


Assuntos
Heterophyidae/classificação , Heterophyidae/genética , Filogenia , Animais , DNA Espaçador Ribossômico/genética , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Japão , RNA Ribossômico 28S/genética , Especificidade da Espécie
15.
Vet Parasitol ; 198(1-2): 230-4, 2013 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-24029716

RESUMO

Fish-borne zoonotic trematode (FZT) infections affect the health of more than 18 million people around the world, particularly in Asian countries. Nile tilapia (Oreochromis niloticus) is a white meat fish that has an increasing national and international market. The objective of this study was to determine the prevalence of FZT metacercarial infections in Nile tilapia from cage and pond aquaculture systems and in wild-caught fish from Suphan Buri, Nakhon Pathom and Chachoengsao provinces, Thailand. Fish were collected from four cages in Suphan Buri and four ponds in Nakhon Pathom provinces between September-October 2011 and April-May 2012 and wild-caught fish were collected in May 2012. All fish were examined for metacercariae by a pepsin digestion and metacercariae identified using morphological and molecular methods. During the first sampling of tilapia the prevalence of metacercariae in cage culture fish were 2.5% and 10% in pond culture fish. During the second sampling, metacercariae was found in 2.0% of tilapia from cage and none from the ponds. Of the 150 wild-caught fish, a total of 80 (53.3%) were found to be infected with metacercariae, mostly the zoonotic species Stellantchasmus falcatus, Haplorchis pumilio and Procerovum varium. The results revealed a low risk for FZT in Nile tilapia cultured in cage and pond aquaculture systems. However, the high prevalence of FZT in wild-caught fish indicates a high potential for spillover from wild reservoir hosts and underscores the need for vigilance and good management practices by the aquaculture sector.


Assuntos
Doenças dos Peixes/parasitologia , Trematódeos/classificação , Infecções por Trematódeos/veterinária , Animais , Doenças dos Peixes/epidemiologia , Peixes , Parasitologia de Alimentos , Doenças Transmitidas por Alimentos/parasitologia , Humanos , Tailândia/epidemiologia , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/parasitologia , Zoonoses
16.
J Parasitol Res ; 2013: 310605, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23864933

RESUMO

Taenia saginata is the most common human Taenia in Thailand. By cox1 sequences, 73 isolates from four localities in north and northeast were differentiated into 14 haplotypes, 11 variation sites and haplotype diversity of 0.683. Among 14 haplotypes, haplotype A was the major (52.1%), followed by haplotype B (21.9%). Clustering diagram of Thai and GenBank sequences indicated mixed phylogeny among localities. By MJ analysis, haplotype clustering relationships showed paired-stars-like network, having two main cores surrounded by minor haplotypes. Tajima's D values were significantly negative in T. saginata world population, suggesting population expansion. Significant Fu's F s values in Thai, as well as world population, also indicate that population is expanding and may be hitchhiking as part of selective sweep. Haplotype B and its dispersion were only found in populations from Thailand. Haplotype B may evolve and ultimately become an ancestor of future populations in Thailand. Haplotype A seems to be dispersion haplotype, not just in Thailand, but worldwide. High genetic T. saginata intraspecies divergence was found, in contrast to its sister species, T. asiatica; among 30 samples from seven countries, its haplotype diversity was 0.067, while only 2 haplotypes were revealed. This extremely low intraspecific variation suggests that T. asiatica could be an endangered species.

17.
Korean J Parasitol ; 51(1): 55-9, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23467439

RESUMO

Twelve 924 bp cytochrome c oxidase subunit 1 (cox1) mitochondrial DNA sequences from Taenia asiatica isolates from Thailand were aligned and compared with multiple sequence isolates from Thailand and 6 other countries from the GenBank database. The genetic divergence of T. asiatica was also compared with Taenia saginata database sequences from 6 different countries in Asia, including Thailand, and 3 countries from other continents. The results showed that there were minor genetic variations within T. asiatica species, while high intraspecies variation was found in T. saginata. There were only 2 haplotypes and 1 polymorphic site found in T. asiatica, but 8 haplotypes and 9 polymorphic sites in T. saginata. Haplotype diversity was very low, 0.067, in T. asiatica and high, 0.700, in T. saginata. The very low genetic diversity suggested that T. asiatica may be at a risk due to the loss of potential adaptive alleles, resulting in reduced viability and decreased responses to environmental changes, which may endanger the species.


Assuntos
Complexo IV da Cadeia de Transporte de Elétrons/genética , Variação Genética , Filogeografia , Taenia/classificação , Taenia/genética , Teníase/epidemiologia , Teníase/parasitologia , Animais , Ásia/epidemiologia , Análise por Conglomerados , Genótipo , Humanos , Dados de Sequência Molecular , Subunidades Proteicas/genética , Análise de Sequência de DNA , Taenia/isolamento & purificação
18.
Artigo em Inglês | MEDLINE | ID: mdl-23077835

RESUMO

Angiostrongylus cantonensis is the causative agent of angiostrongyliasis, which is widely distributed throughout the world. It can specifically infect many species of intermediate and definitive hosts. This study examined the genetic differentiation and population structure using the RAPD-PCR method of parasites obtained from 8 different geographical areas of Thailand. Based on 8 primers, high levels of genetic diversity and low levels of gene flow among populations were found. Using genetic distance and neighbor-joining dendrogram methods, A. cantonensis in Thailand could be divided into two groups with statistically significant genetic differentiation of the two populations. However, genotypic variations and haplotype relationships need to be further elucidated using other markers.


Assuntos
Angiostrongylus cantonensis/genética , Variação Genética , Angiostrongylus cantonensis/classificação , Angiostrongylus cantonensis/isolamento & purificação , Animais , Genes de Helmintos , Genótipo , Humanos , Reação em Cadeia da Polimerase , Polimorfismo Genético , Ratos , Ratos Wistar , Análise de Sequência de DNA , Tailândia/epidemiologia
19.
Artigo em Inglês | MEDLINE | ID: mdl-23413695

RESUMO

Over 70 countries in tropical and subtropical zones are endemic areas for Strongyloides stercoralis, with a higher prevalence of the parasite often occurring in tropical regions compared to subtropical ones. In order to explore genetic variations of S. stercoralis form different climate zones, 18S ribosomal DNA of parasite specimens obtained from Thailand were sequenced and compared with those from Japan. The maximum likelihood indicates that S. stercoralis populations from these two different climate zones have genetically diverged. The genetic relationship between S. stercoralis populations is not related to the host species, but rather to moisture and temperature. These factors may directly drive genetic differentiation among isolated populations of S. stercoralis.


Assuntos
Variação Genética , RNA Ribossômico 18S/genética , Strongyloides stercoralis/genética , Estrongiloidíase/parasitologia , Clima Tropical , Animais , Fezes/parasitologia , Humanos , Japão , RNA Ribossômico 18S/isolamento & purificação , Strongyloides stercoralis/isolamento & purificação , Estrongiloidíase/epidemiologia , Tailândia
20.
Parasitol Int ; 61(1): 90-3, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21740979

RESUMO

Superfamily Opisthorchioidea Looss, 1899 consists of three well-known families, Opisthorchiidae, Heterophyidae, and Cryptogonimidae, with basic similarities in morphology and life-cycles. Many species in the first two of these families are human pathogens, such as Opisthorchis viverrini, O. felineus, Clonorchis sinensis, Haplorchis spp. and Metagonimus spp. Recently, a molecular phylogenetic study on the classification of Digenea revealed a paraphyletic relationship between Opisthorchiidae and Heterophyidae. For our study, we gathered and analyzed all available data in GenBank, together with new data of nuclear 18S ribosomal DNA and ribosomal internal transcribed spacer 2 (ITS2) sequences of the families within the Opisthorchioidea. Maximum likelihood and Bayesian inference analyses suggested that families Opisthorchiidae and Heterophyidae are inseparable from each other, with the former nested within the latter. Groupings in molecular trees are generally consistent with morphological features used in taxonomy.


Assuntos
DNA de Helmintos/genética , Heterophyidae/classificação , Heterophyidae/genética , Opisthorchidae/classificação , Opisthorchidae/genética , Animais , Teorema de Bayes , DNA Espaçador Ribossômico/genética , Funções Verossimilhança , Dados de Sequência Molecular , Filogenia , RNA Ribossômico 18S/genética , Alinhamento de Sequência , Análise de Sequência de DNA , Trematódeos/classificação , Trematódeos/genética
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