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

Risk factors analysis for neglected human rickettsioses in rural communities in Nan province, Thailand: a community-based observational study along a landscape gradient.

In this study, we estimated exposure for Scrub typhus (STG), Typhus (TG) and Spotted fever groups (SFG) rickettsia using serology at a fine scale (a whole sub-district administration level) of local communities in Nan Province, Thailand. Geographical characteristics of the sub-district were divided into two landscape types: lowland agricultural area in an urbanized setting (lowland-urbanized area) and upland agricultural area located close to a protected area of National Park (upland-forested area). This provided an ideal contrast between the two landscapes with low and high levels of human-altered habitats to study in differences in disease ecology. In total, 824 serum samples of participants residing in the eight villages were tested by screening IgG ELISA, and subsequently confirmed by the gold standard IgG Immunofluorescent Assay (IFA). STG and TG IgG positivity were highest with seroprevalence of 9.8% and 9.0%, respectively; whereas SFG positivity was lower at 6.9%. Inhabitants from the villages located in upland-forested area demonstrated significantly higher STG exposure, compared to those villages in the lowland-urbanized area (chi-square = 51.97, p < 0.0001). In contrast, TG exposure was significantly higher in those villagers living in lowland-urbanized area (chi-square = 28.26, p < 0.0001). In addition to the effect of landscape types, generalized linear model (GLM) analysis identified socio-demographic parameters, i.e., gender, occupation, age, educational level, domestic animal ownership (dog, cattle and poultry) as influential factors to explain the level of rickettsial exposure (antibody titers) in the communities. Our findings raise the public health awareness of rickettsiosis as a cause of undiagnosed febrile illness in the communities

Prevalence and molecular characterization of Rickettsia spp. from wild small mammals in public parks and urban areas of Bangkok Metropolitan, Thailand

Rural areas usually show a higher prevalence of rickettsial infection than urban areas. However, information on the rickettsial infection status in urban settings (e.g., built-up areas and city parks) is still limited, particularly in the Bangkok metropolitan area. In this study, we performed a molecular rickettsial survey of spleen samples of small mammals caught in public parks and built-up areas of Bangkok. Out of 198 samples, the Rattus rattus complex was found to be most prevalent. The amplification of rickettsial gltA fragment gene (338 bp) by nested PCR assay revealed positive results in four samples, yielding a low prevalence of infection of 2.02%. DNA sequencing results confirmed that three samples were matched with Rickettsia typhi, and one was identified as R. felis. It is noteworthy that this is the first report of the occurrence of R. felis DNA in rodents in Southeast Asia

Sensitive and accurate DNA metabarcoding of parasitic helminth mock communities using the mitochondrial rRNA genes

Next-generation sequencing technologies have accelerated the pace of helminth DNA metabarcoding research, enabling species detection in bulk community samples. However, finding suitable genetic markers with robust species-level resolution and primers targeting a broad species range among parasitic helminths are some of the challenges faced. This study aimed to demonstrate the potential use of the mitochondrial 12S and 16S rRNA genes for parasitic helminth (nematodes, trematodes, cestodes) DNA metabarcoding. To demonstrate the robustness of the 12S and 16S rRNA genes for DNA metabarcoding, we determined the proportion of species successfully recovered using mock helminth communities without environment matrix and mock helminth communities artificially spiked with environmental matrices. The environmental matrices are human fecal material, garden soil, tissue, and pond water. Our results revealed the robustness of the mitochondrial rRNA genes, through the high sensitivity of the 12S rRNA gene, and the effectiveness of the 12S and 16S primers targeting platyhelminths. With the mitochondrial rRNA genes, a broad range of parasitc helminths were successfully detected to the species level. The potential of the mitochondrial rRNA genes for helminth DNA metabarcoding was demonstrated, providing a valuable gateway for future helminth DNA metabarcoding applications like helminth detection and biodiversity studies

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