Notocotylus Loeiensis n. sp. (Trematoda: Notocotylidae) from Rattus Losea (Rodentia: Muridae) in Thailand

Notocotylus loeiensis n. sp. (Trematoda : Notocotylidae) du caecum du petit rat des rizières (Rattus losea) a été observé chez huit rats sur 88 (9,1 %) dans la province de Loei en Thaïlande. Cette nouvelle espèce diffère de celles de Notocotylus décrites précédemment, principalement par la position prébifurcale extrême du pore génital et par le nombre de papilles ventrales. Il s'agit de la première description du niveau d'espèce Notocotylus chez un mammifère en Asie du Sud-Est. (Résumé d'auteur

Symbiosis in an overlooked microcosm: a systematic review of the bacterial flora of mites

A dataset of bacterial diversity found in mites was compiled from 193 publications (from 1964 to January 2015). A total of 143 mite species belonging to the 3 orders (Mesostigmata, Sarcoptiformes and Trombidiformes) were recorded and found to be associated with approximately 150 bacteria species (in 85 genera, 51 families, 25 orders and 7 phyla). From the literature, the intracellular symbiont Cardinium, the scrub typhus agent Orientia, and Wolbachia (the most prevalent symbiont of arthropods) were the dominant mite-associated bacteria, with approximately 30 mite species infected each. Moreover, a number of bacteria of medical and veterinary importance were also reported from mites, including species from the genera Rickettsia, Anaplasma, Bartonella, Francisella, Coxiella, Borrelia, Salmonella, Erysipelothrix and Serratia. Significant differences in bacterial infection patterns among mite taxa were identified. These data will not only be useful for raising awareness of the potential for mites to transmit disease, but also enable a deeper understanding of the relationship of symbionts with their arthropod hosts, and may facilitate the development of intervention tools for disease vector control. This review provides a comprehensive overview of mite-associated bacteria and is a valuable reference database for future research on mites of agricultural, veterinary and/or medical importance. (Résumé d'auteur

Aonchotheca yannickchavali n. sp. (Nematoda: Capillariidae) in Bandicota indica (Bechstein, 1800) and Bandicota savilei (Thomas, 1916) from Thailand

During previous surveys of helminths in rodents from Southeast Asia, an unnamed species ofAoncho-thecawas recovered from the stomach of several rodent species. In the present study, the description ofthe new speciesAonchotheca yannickchavalin. sp. is provided based on both female and male specimenscollected from two bandicoot rat species (Bandicota indicaandBandicota savilei) from Thailand (Buriramand Nan provinces). This nematode can be separated from other knownAonchothecafound in rodents byits microhabitat in the host and by the size of the spicules in males and the vulvar appendage in females

The chigger microbiome: big questions in a tiny world.

'Chiggers' (trombiculid mite larvae) are best known as vectors of rickettsial pathogens, Orientia spp., which cause a zoonosis, scrub typhus. However, several other pathogens (e.g., Hantaan orthohantavirus, Dabie bandavirus, Anaplasma spp., Bartonella spp., Borrelia spp., and Rickettsia spp.) and bacterial symbionts (e.g., Cardinium, Rickettsiella, and Wolbachia) are being reported from chiggers with increasing frequency. Here, we explore the surprisingly diverse chigger microbiota and potential interactions within this microcosm. Key conclusions include a possible role for chiggers as vectors of viral diseases; the dominance in some chigger populations of unidentified symbionts in several bacterial families; and increasing evidence for vertical transmission of potential pathogens and symbiotic bacteria in chiggers, suggesting intimate interactions and not simply incidental acquisition of bacteria from the environment or host

Ecological and microbiological diversity of chigger mites, including vectors of scrub typhus, on small mammals across stratified habitats in Thailand

Background Scrub typhus, caused by a bacterial pathogen (Orientia spp.), is a potentially life-threatening febrile illness widely distributed in the Asia-Pacific region and is emerging elsewhere. The infection is transmitted by the larval stage of trombiculid mites (“chiggers”) that often exhibit low host specificity. Here, we present an analysis of chigger ecology for 38 species sampled from 11 provinces of Thailand and microbiomes for eight widespread species. Results In total, > 16,000 individual chiggers were collected from 1574 small mammal specimens belonging to 18 species across four horizontally-stratified habitat types. Chigger species richness was positively associated with higher latitudes, dry seasonal conditions, and host maturity; but negatively associated with increased human land use. Human scrub typhus incidence was found to be positively correlated with chigger species richness. The bacterial microbiome of chiggers was highly diverse, with Sphingobium, Mycobacterium, Neisseriaceae and various Bacillales representing the most abundant taxa. Only Leptotrombidium deliense was found to be infected with Orientia and another potential pathogen, Borrelia spp., was frequently detected in pools of this species. β-diversity, but not α-diversity, was significantly different between chigger species and geographic regions, although not between habitat types. Conclusion Our study identified several key environmental and host-derived correlates of chigger species richness across Thailand, which in turn impacted on human scrub typhus incidence. Moreover, this first extensive field survey of the chigger microbiome revealed species- and province-level variation in microbial β-diversity across the country, providing a framework for future studies on interactions between pathogens and other symbionts in these understudied vectors

Intestinal parasitic infections and environmental water contamination in a rural village of northern Lao PDR

A field survey studying intestinal parasites in humans and microbial pathogen contamination at environment was performed in a Laotian rural village to identify potential risks for disease outbreaks. A parasitological investigation was conducted in Ban Lak Sip village, Luang Prabang, Lao PDR involving fecal samples from 305 inhabitants as well as water samples taken from 3 sites of the local stream. Water analysis indicated the presence of several enteric pathogens, i.e., Aeromonas spp., Vibrio spp., E. coli H7, E. coli O157: H7, verocytotoxin-producing E. coli (VTEC), Shigella spp., and enteric adenovirus. The level of microbial pathogens contamination was associated with human activity, with greater levels of contamination found at the downstream site compared to the site at the village and upstream, respectively. Regarding intestinal parasites, the prevalence of helminth and protozoan infections were 68.9% and 27.2%, respectively. Eight helminth taxa were identified in fecal samples, i.e., 2 tapeworm species (Taenia sp. and Hymenolepis diminuta), 1 trematode (Opisthorchis sp.), and 5 nematodes (Ascaris lumbricoides, Trichuris trichiura, Strongyloides stercoralis, trichostrongylids, and hookworms). Six species of intestinal protists were identified, i.e., Blastocystis hominis, Cyclospora spp., Endolimax nana, Entamoeba histolytica/E. dispar, Entamoeba coli, and Giardia lamblia. Questionnaires and interviews were also conducted to determine risk factors of infection. These analyses together with a prevailing infection level suggested that most of villagers were exposed to parasites in a similar degree due to limited socio-economic differences and sharing of similar practices. Limited access to effective public health facilities is also a significant contributing factor

Autofluorescence microscopy for paired-matched morphological and molecular identification of individual chigger mites (Acari: Trombiculidae), the vectors of scrub typhus

<div><p>Background</p><p>Conventional gold standard characterization of chigger mites involves chemical preparation procedures (i.e. specimen clearing) for visualization of morphological features, which however contributes to destruction of the arthropod host DNA and any endosymbiont or pathogen DNA harbored within the specimen.</p><p>Methodology/Principal findings</p><p>In this study, a novel work flow based on autofluorescence microscopy was developed to enable identification of trombiculid mites to the species level on the basis of morphological traits without any special preparation, while preserving the mite DNA for subsequent genotyping. A panel of 16 specifically selected fluorescence microscopy images of mite features from available identification keys served for complete chigger morphological identification to the species level, and was paired with corresponding genotype data. We evaluated and validated this method for paired chigger morphological and genotypic ID using the mitochondrial cytochrome c oxidase subunit I gene (<i>coi</i>) in 113 chigger specimens representing 12 species and 7 genera (<i>Leptotrombidium</i>, <i>Ascoschoengastia</i>, <i>Gahrliepia</i>, <i>Walchia</i>, <i>Blankaartia</i>, <i>Schoengastia</i> and <i>Schoutedenichia</i>) from the Lao People’s Democratic Republic (Lao PDR) to the species level (complete characterization), and 153 chiggers from 5 genera (<i>Leptotrombidium</i>, <i>Ascoschoengastia</i>, <i>Helenicula</i>, <i>Schoengastiella</i> and <i>Walchia)</i> from Thailand, Cambodia and Lao PDR to the genus level.</p><p>A phylogenetic tree constructed from 77 <i>coi</i> gene sequences (approximately 640 bp length, n = 52 new <i>coi</i> sequences and n = 25 downloaded from GenBank), demonstrated clear grouping of assigned morphotypes at the genus levels, although evidence of both genetic polymorphism and morphological plasticity was found.</p><p>Conclusions/Significance</p><p>With this new methodology, we provided the largest collection of characterized <i>coi</i> gene sequences for trombiculid mites to date, and almost doubled the number of available characterized <i>coi</i> gene sequences with a single study. The ability to provide paired phenotypic-genotypic data is of central importance for future characterization of mites and dissecting the molecular epidemiology of mites transmitting diseases like scrub typhus.</p></div

Redescription and new record of Paracapillaria (Ophidiocapillaria) najae (Nematoda: Trichuroidea) in the monocled cobra Naja kaouthia from central Thailand: morphological and molecular insights

The parasitic nematode Paracapillaria (Ophidiocapillaria) najae De, 1998, found in the Indian cobra Naja naja is redescribed and re-illustrated in the present study. The monocled cobra Naja kaouthia was discovered to be a new host for this parasite in central Thailand. A comprehensive description extending the morphological and molecular characteristics of the parasites is provided to aid species recognition in future studies. The morphometric characters of 41 parasites collected from 5 cobra specimens are compared with those described in the original studies. Phylogenetic analyses using mitochondrial cytochrome c oxidase subunit 1 and nuclear 18S ribosomal RNA genes were performed to provide novel information on the systematics of P. najae. Similar characteristics were observed in the examined nematode samples, despite being found in different hosts, confirming their identity as P. najae. The molecular genetic results support the species status of P. najae, indicating P. najae is well defined and separated from other related nematode species in the family Capillariidae. Morphological descriptions, genetic sequences, evolutionary relationships among capillariids and new host and distribution records of P. najae are discussed. Paracapillaria najae specimens found in the Thai cobra had some morphological variation, and sexual size dimorphism was also indicated. Paracapillaria najae was found to infect various cobra host species and appeared to be common throughout the Oriental regions, consistent with its hosts' distribution