High prevalence and low diversity of chigger infestation in small mammals found in Bangkok Metropolitan parks.

Chiggers are recognized as vectors of scrub typhus disease caused by the bacteria, Orientia tsutsugamushi. The risk of disease exposure is mainly related to chigger bites when humans or animals roam into vector-infested habitats. In big cities, urban public parks could provide areas for the animal-human interface and zoonotic pathogen transmission. The ecology and epidemiology of urban scrub typhus are still poorly understood in Thailand. Small mammals were trapped and examined for chigger infestation in urban public parks across metropolitan Bangkok, Thailand. We found a high prevalence of infestation (76.8%) with surprisingly low diversity. Two chigger species, Leptotrombidium deliense and Ascoschoengastia indica, were identified using morphological characteristics and molecular confirmation. The generalized linear model identified host intrinsic variables (i.e. body mass index) with host density, habitat composition and open field as the extrinsic factors explaining the abundance of chigger infestation. The bacteria O. tsutsugamushi was not detected in chiggers (90 chigger-pooled samples) and animal host tissues (164 spleen samples). However, the existence of chigger vectors calls for the Bangkok Metropolitan Administration and public health authorities to develop a comprehensive scrub typhus monitoring and prevention strategy in the parks and nearby communities.

Distribution of the newly invasive New Guinea flatworm Platydemus manokwari (Platyhelminthes: Geoplanidae) in Thailand and its potential role as a paratenic host carrying Angiostrongylus malaysiensis larvae.

Invasive species constitute one of the most serious threats to biodiversity and ecosystems, and they potentially cause economic problems and impact human health. The globally invasive New Guinea flatworm, Platydemus manokwari (Platyhelminthes: Geoplanidae), has been identified as a threat to terrestrial biodiversity, particularly soil-dwelling native species (e.g. molluscs, annelids and other land planarians), and is listed among 100 of the world's worst invasive alien species. We report here, for the first time, P. manokwari occurrences in many locations throughout Thailand, using voluntary digital public participation from the social network portals associated with the Thailand Biodiversity Conservation Group and collections of living flatworm specimens. Mitochondrial cytochrome c oxidase subunit I (COI) sequences confirmed that all collected flatworms were P. manokwari and placed them in the "world haplotype" clade alongside other previously reported specimens from France, Florida (USA), Puerto Rico, Singapore, French Polynesia, New Caledonia, and the Solomon Islands. In addition, infective stage larvae (L3) of the nematode Angiostrongylus malaysiensis were found in the flatworm specimens, with a 12.4% infection rate (15/121 specimens examined). Platydemus manokwari occurrence in Thailand and its capacity to carry L3 of Angiostrongylus should be of concern to biodiversity conservation and human health practitioners, because this invasive flatworm species may be involved in the life cycle of angiostrongylid worms in Thailand.

Parasitic infections in relation to practices and knowledge in a rural village in Northern Thailand with emphasis on fish-borne trematode infection.

The present study integrates several aspects of a parasitological survey in a rural community village combining community knowledge of parasites, their potential transmission routes and health risk factors. A rural community located in Northern Thailand was surveyed for intestinal parasites, and an overall prevalence of 45.2% for helminths and 4.8% for protozoan infections was identified. Socio-demographic characteristics, customs and perceptions were compiled using individual questionnaires and interviews for participants surveyed for parasitic screening. The results allowed us to determine the knowledge and perception of local people concerning helminthic infection and transmission. Despite the fact that the participants in this community were aware of parasitic transmission routes, their widespread custom of eating raw fish and meat render the reduction of helminthiasis difficult. A detailed study on the infection of fish-borne parasitic trematodes, the most prevalent helminth, allowed us to determine that the distance from a given household to the river is a determinant of infection intensity. Health education activities organised in the local community resulted in a change in perception of risks associated with parasite transmission.

Gastrointestinal helminth fauna of rodents from Cambodia: emphasizing the community ecology of host-parasite associations.

Extensive field surveys of rodents were conducted in Cambodia from 2008 to 2014 to study the diversity and ecology of helminth infection in wild rodent populations. Gastrointestinal helminths were isolated from 14 species of rodents (569 individuals) trapped from different habitats (forest, dry land, rain-fed land and human settlements) in four provinces of Cambodia (Krong Preah Sihanouk, Mondolkiri, Pursat and Steung Treng). The average prevalence of parasitic infection was 58.5% (range, 16.0-64.7%), and 19 helminth taxa were identified in total. Trichostrongylid nematodes were the most prevalent (25.8%), followed by Raillietina sp. (14.1%), Gongylonema neoplasticum (10.7%), Syphacia muris (9.8%) and Hymenolepis diminuta (9.6%). Potential rodent-borne zoonotic helminths were also identified, and the risks of helminthiasis were discussed. The status of helminth infection and species diversity in rodents from settlements were significantly lower than in rodents from forest and peri-domesticated habitats, which indicates that habitat alteration might affect helminth infection and diversity in rodent hosts. Generalized linear models revealed that host attributes (host species and maturity) and environmental factors (habitat and geographical location) were explanatory variables for helminth infection in these rodents. Using network analyses, we showed that the oriental house rat, Rattus tanezumi, was the most central host in the rodent-helminth assemblage, based on the number of helminth taxa it shared with other rodent species. Therefore, R. tanezumi could play an important role in rodent-helminth interactions and helminth transmission to other rodent hosts.

Environmental factors and public health policy associated with human and rodent infection by leptospirosis: a land cover-based study in Nan province, Thailand.

Leptospirosis incidence has increased markedly since 1995 in Thailand, with the eastern and northern parts being the most affected regions, particularly during flooding events. Here, we attempt to overview the evolution of human prevalence during the past decade and identify the environmental factors that correlate with the incidence of leptospirosis and the clinical incidence in humans. We used an extensive survey of Leptospira infection in rodents conducted in 2008 and 2009 and the human incidence of the disease from 2003 to 2012 in 168 villages of two districts of Nan province in Northern Thailand. Using an ad-hoc developed land-use cover implemented in a geographical information system we showed that humans and rodents were not infected in the same environment/habitat in the land-use cover. High village prevalence was observed in open habitat near rivers for the whole decade, or in 2008-2009 mostly in rice fields prone to flooding, whereas infected rodents (2008-2009) were observed in patchy habitat with high forest cover, mostly situated on sloping ground areas. We also investigated the potential effects of public health campaigns conducted after the dramatic flood event of 2006. We showed that, before 2006, human incidence in villages was explained by the population size of the village according to the environmental source of infection of this disease, while as a result of the campaigns, human incidence in villages after 2006 appeared independent of their population size. This study confirms the role of the environment and particularly land use, in the transmission of bacteria, emphasized by the effects of the provincial public health campaigns on the epidemiological pattern of incidence, and questions the role of rodents as reservoirs.

[RATS OF THE GENUS RATTUS AS HOSTS FOR NATURAL FOCAL INFECTIOUS AGENTS].

The paper reviews the significance of rats of the genus Rattus as hosts for zoogenous infections in a genus formation area (Southeast Asia) as compared to the invasion part of the genus area. The rats of the genus Rattus and their related disease agents are shown to be a uniqe model for the formation and development of a host-pathogen system. In the modern period of urbanization growth, the rats are among few species of warm-blooded vectors that can maintain the anthropurgic foci of feral nidal infections in the cities and towns and transmit their pathogens to the urban population. There are all prerequisites for the high activity of these foci in the native area of rats. By having settled, the rats have carried infectious agents outside this area along all continents in historical times. During invasions, the rats have become carriers of many other infections.

Molecular prevalence of Trypanosoma spp. in wild rodents of Southeast Asia: influence of human settlement habitat.

SUMMARY: This study investigated the molecular prevalence of Trypanosoma lewisi and T. evansi in wild rodents from Cambodia, Lao PDR and Thailand. Between 2008 and 2012, rodents (and shrews) were trapped in nine locations and 616 of these were tested using three sets of primers: TRYP1 (amplifying ITS1 of ribosomal DNA of all trypanosomes), TBR (amplifying satellite genomic DNA of Trypanozoon parasites) and LEW1 (amplifying ITS1 of ribosomal DNA of T. lewisi). Based on the size of the PCR products using TRYP1, 17% were positive for T. lewisi and 1·0% positive for Trypanozoon. Results were confirmed by sequencing PCR products and by using more specific primers (LEW1 and TBR). The specificity of TRYP1 primers, however, failed as rodent DNA was amplified in some instances, giving unexpected product sizes. Using LEW1 primers, 13·3% of the samples were confirmed positive for T. lewisi, both by PCR and sequencing. In Thailand, T. lewisi was found in Rattus tanezumi, R. exulans and Berylmys; in Lao PDR, in R. tanezumi and R. exulans, and in Cambodia in R. tanezumi, R. exulans and R. norvegicus. Using TBR, 1·3% of the samples tested positive for Trypanozoon by PCR and sequencing; T. evansi is the only species of the Trypanozoon subgenus possibly present in wild Asian rodents. These results confirmed its presence in rodents from Thailand (R. tanezumi), Lao PDR (R. tanezumi, R. nitidus) and Cambodia (R. tanezumi, Niviventer fulvescens, Maxomys surifer). Based on the information related to rodent trapping, it was found that rodent species trapped in and around human dwellings had a higher prevalence of T. lewisi infection. R. tanezumi and R. exulans, two synanthropic species, were mainly found infected in this habitat suggesting a role as a reservoir and thus a potential source of T. lewisi for human infection.

Positive co-occurrence of flea infestation at a low biological cost in two rodent hosts in the Canary archipelago.

Non-random assemblages have been described as a common pattern of flea co-occurrence across mainland host species. However, to date, patterns of flea co-occurrence on islands are unknown. The present work investigates, on one hand, whether the decrease in the number of species on islands affects the pattern of flea co-occurrence, and on the other hand, how the cost of higher flea burdens affects host body mass. The study was carried out in the Canary Islands (Spain) using null models to analyse flea co-occurrence on Rattus rattus and Mus musculus. Results supported aggregation of flea species in Mus but not in Rattus, probably due to the relationship between abundance and both prevalence and intensity of infection of the main flea species parasitizing Mus. In addition, heavy individuals of both rodent species showed the highest flea burdens as well as higher species richness, probably due to the continued accumulation of fleas throughout life and/or immunological resistance mechanisms. Whatever the mechanisms involved, it is clear that co-occurrence and high parasite intensities do not imply a detrimental biological cost for the rodents of the Canary Islands.

Helminth communities in murid rodents from southern and northern localities in Lao PDR: the role of habitat and season.

The helminth communities of wild murid rodents were investigated in Luang Prabang and Champasak province, Lao PDR. Thirteen species of rodents (404 individuals) were infected by 19 species of parasites (2 trematode, 3 cestode, 14 nematode species). Four of the recorded helminth species (Echinostoma malayanum, Raillietina sp., Hymenolepis diminuta and H. nana) are known to cause potential zoonotic helminthiases of medical importance in the South-East Asian region. Individual helminth infection was significantly higher in the wet season. Habitat significantly influenced individual helminth species richness and individual helminth abudance, with a decrease of individual helminth species richness and individual helminth abundance from forest habitat to agricultural and human settlement habitats. The reduction of helminth diversity and abundance is discussed in relation to the ongoing increase of human influence on habitats in Lao PDR.

New digeneans (Opecoelidae) from hydrothermal vent fishes in the south eastern Pacific Ocean, including one new genus and five new species.

A new genus and five new species of digeneans are reported from fishes at hydrothermal vent sites in the South East Pacific Rise region. Biospeedotrema n. gen. (Opecoelidae: Stenakrinae) is distinguished from other stenakrines by the more or less symmetrical testicular configuration, with the uterus passing between the testes, sometimes distinctly into the post-testicular region. Biospeedotrema jolliveti n. gen., n. sp. from Ventichthys biospeedoi (Ophidiidae) is distinguished by the vitelline fields which extend only slightly into the post-testicular region, the intestinal bifurcation is dorsal to the ventral sucker, the genital pore is slightly dextrally submedian or median, the cirrus sac is short and the caeca are broad and overlap the testes, usually reaching into the post-testicular region. Biospeedotrema parajolliveti n. sp. from Thermichthys hollisi differs from Biospeedotrema jolliveti in being squat, always just wider than long, the tegument is wrinkled, the testes are lobate, and the caeca only just reach to the testes. Biospeedotrema biospeedoi n. sp. from T. hollisi differs from its congeners in its body-shape, uterine extent posterior to the testes and the small vitellarium. Caudotestis ventichthysi n. sp. (Opecoelidae: Stenakrinae) from V. biospeedoi is distinguished from its five congeners in various combinations of caecal length, cirrus sac length, internal seminal vesicle shape, vitelline extent and distribution, forebody length and egg-size. Buticulotrema thermichthysi n. sp. (Opecoelidae: Opecoelininae) from T. hollisi (Bythitidae) is distinguished from its only congener by its very long, very strongly muscular oesophagus, bifurcating dorsally to the posterior part of the ventral sucker, the long, narrow pars prostatica and distal male duct and the sinistral genital pore at the level of the pharynx. The phylogenetic position for three of these species, Buticulotrema thermichthysi, Biospeedotrema jolliveti and Biospeedotrema biospeedoi, is assessed based on ssrDNA and lsrDNA sequences, which verify the position of these species in the Opecoelidae. 

Cricothyroidotomy in extreme emergency: A case report of a real-life experience in three steps and less than 30 s using a single blade.

INTRODUCTION AND IMPORTANCE: Cricothyroidotomy is often the last resort when conventional ventilation devices prove ineffective. The conventional procedure that involves several steps and requires the completion of a preoperative checklist. This report describes a novel approach to cricothyroidotomy, allowing quick access to the cricothyroid membrane in fewer steps. CASE PRESENTATION: We present the case of a 26-year-old male with Schimmelpenning syndrome, exhibiting significant anatomical deformity. Following surgery for temporomandibular joint replacement, the patient developed a hematoma requiring urgent intervention. During nasotracheal intubation, the patient experienced a significant drop in oxygen saturation, which required prompt cricothyroidotomy. The procedure was performed in less than 30 s using a single blade for incising the tissues and the surgeon's hands for dissection and retraction. The procedure resulted in immediate recovery of the patient's oxygen saturation. CLINICAL DISCUSSION: In contrast to previously reported multi-step procedures, this study reports a simpler three-step cricothyroidotomy. The technique involves a vertical skin incision, blunt dissection using the surgeon's fingers, and a horizontal incision on the cricothyroid membrane. The procedure was executed with the patient in a semi-reclined position, optimizing time efficiency. CONCLUSION: This case highlights the efficacy of a rapid cricothyroidotomy technique in extreme emergencies. The presented technique requires minimal instrumentation and can be completed quickly in an emergency situation, even in the presence of anatomical variations.

Larval habitat segregation between the molecular forms of the mosquito Anopheles gambiae in a rice field area of Burkina Faso, West Africa.

In West Africa, lineage splitting between the M and S molecular forms of the major Afro-tropical malaria mosquito, Anopheles gambiae (Diptera: Culicidae), is thought to be driven by ecological divergence, occurring mainly at the larval stage. Here, we present evidence for habitat segregation between the two molecular forms in and around irrigated rice fields located within the humid savannahs of western Burkina Faso. Longitudinal sampling of adult mosquitoes emerging from a range of breeding sites distributed along a transect extending from the heart of the rice field area into the surrounding savannah was conducted from June to November 2009. Analysis revealed that the two molecular forms and their sibling species Anopheles arabiensis are not randomly distributed in the area. A major ecological gradient was extracted in relation to the perimeter of the rice fields. The M form was associated with larger breeding sites mostly consisting of rice paddies, whereas the S form and An. arabiensis were found to depend upon temporary, rain-filled breeding sites. These results support hypotheses about larval habitat segregation and confirm the suggestion that the forms have different larval habitat requirements. Segregation appears to be clearly linked to anthropogenic permanent habitats and the community structure they support.

Notocotylus loeiensis N. sp. (Trematoda: Notocotylidae) from Rattus losea (Rodentia: Muridae) in Thailand.

Notocotylus loeiensis n. sp. (Trematoda: Notocotylidae) is described from the cecum of the lesser rice field rat (Rattus losea), from Loei Province in Thailand with a prevalence of 9.1% (eight of 88 rats infected). The new species differs from previously described Notocotylus species mainly by the extreme prebifurcal position of the genital pore and the number of ventral papillae. This is the first description at the species level of Notocotylus from mammals in Southeast Asia.

Gill ectoparasites of Barbus martorelli (Teleostean: Cyprinidae) from a tropical watercourse (Cameroon, Africa): conflict or coexistence?

The structure and stability of parasite communities have been mainly explained by high diversity and strong interactions among parasite species. During 16 months, 558 Barbus martorelli gill infracommunities were studied in a tropical zone to determine whether parasite infrapopulations interact. Three levels were retained: the infracommunity level, the gill filament level, and the filament fraction level. Single species infections in Barbus martorelli were very rare and only concerned the core species: Dactylogyrus bopeleti, D. insolitus, D. simplex and Myxobolus barbi. Mixed infections appeared as a general rule in this fish species. Interspecific interactions at all three levels were statistically non significant. Our results suggest that Barbus martorelli gill parasites are non interactive (isolationist).

3D-printed scaffold combined to 2D osteoinductive coatings to repair a critical-size mandibular bone defect.

The reconstruction of large bone defects (12 cm3) remains a challenge for clinicians. We developed a new critical-size mandibular bone defect model on a minipig, close to human clinical issues. We analyzed the bone reconstruction obtained by a 3D-printed scaffold made of clinical-grade polylactic acid (PLA), coated with a polyelectrolyte film delivering an osteogenic bioactive molecule (BMP-2). We compared the results (computed tomography scans, microcomputed tomography scans, histology) to the gold standard solution, bone autograft. We demonstrated that the dose of BMP-2 delivered from the scaffold significantly influenced the amount of regenerated bone and the repair kinetics, with a clear BMP-2 dose-dependence. Bone was homogeneously formed inside the scaffold without ectopic bone formation. The bone repair was as good as for the bone autograft. The BMP-2 doses applied in our study were reduced 20- to 75-fold compared to the commercial collagen sponges used in the current clinical applications, without any adverse effects. Three-dimensional printed PLA scaffolds loaded with reduced doses of BMP-2 may be a safe and simple solution for large bone defects faced in the clinic.

Biodiversity: an international perspective.

This paper examines the way in which biodiversity has been incorporated into the agenda of many international organisations, including non-governmental organisations, and international programmes. Biodiversity has been defined by the Convention on Biological Diversity but is also widely discussed in relation to genetic resources, biodiversity hotspots and ecosystem services. The author identifies the principal institutions, organisations, conventions and international programmes that specifically refer to biodiversity, the environment or ecosystem services. This more recent 'ecosystem approach' has radically changed the perspective on biodiversity by focusing on the services that biodiversity provides. Finally, this paper stresses the urgent need to develop indicators of the ecosystem services that people and societies gain from biodiversity.

Interactions between immunocompetence, somatic condition and parasitism in the chub Leuciscus cephalus in early spring.

Relationships between immunocompetence, somatic condition, parasitism and water temperature in a wild population of chub Leuciscus cephalus were investigated. The effects of a rapid temperature increase in early spring were studied for both sexes as water temperature affects immunocompetence. Investment in gonads and activity of mucus lysozyme were negatively correlated; lysozyme activity decreased as temperature increased. No correlations were found between lysozyme activity and parasitism or intensity of infection by monogeneans, the most abundant metazoan parasite group in L. cephalus. There was a positive correlation, however, between respiratory burst intensity and parasitism. Indices of investment in gonads and spleen were correlated, showing that energetic reserves allowed either investment in gonads and spleen, or that spleen investment, even if often used in other studies in immunoecology, was not always a significant indicator of immunocompetence during this period. This last proposition is supported by the lack of correlation between spleen investment and other factors linked to immunocompetence.

Molecular detection of divergent trypanosomes among rodents of Thailand.

Herpetosoma is a homogenous subgenus of several dozen named species that are often described as morphologically indistinguishable T. lewisi-like parasites. These trypanosomes normally infect rodents and utilize fleas as vectors. Although this trypanosome subgenus is considered non-pathogenic to normal hosts, some of them are on rare occasion reported in association with human disease. Recently, a T. lewisi-like infection was detected in a sick Thai infant, thus the objective of this study was to investigate the prevalence of T. lewisi infections among different rodents indigenous to Thailand in order to identify possible sources of human cases. Blood was collected from a total of 276 rodents trapped from urban and rural areas of three Thai provinces between 2006 and 2007. These samples were processed for DNA isolation and tested with a PCR assay universal for the genus Trypanosoma, followed by internal transcribed spacer 1 (ITS-1) sequence analysis to identify infections in positive samples. Herpetosoma known as T. lewisi-like trypanosomes were present among Rattus (14.3%) and Bandicota (18.0%) rodent species and salivarian trypanosomes closely related to T. evansi were detected in Leopoldamys (20%) and Rattus (2.0%) species. Herpetosoma were prevalent among rodents associated with both human and sylvatic habitats, while three of the four salivaria-positive rodents were from a forest biotope. A Herpetosoma ITS-1 sequence amplified from one of these samples was 97.9% identical to that reported for T. lewisi in an experimentally infected rat and 96.4% identical to the sequence amplified from blood from a Thai infant. Habitats where rodents were collected significantly affect rodent infection, at least for T. lewisi, suggesting that the degree of anthropization may influence the transmission of Trypanosoma spp. These results suggest that multiple Herpetosoma species or strains are enzootic to Thailand, and that Rattus and Bandicota species are possible sources of human exposure to these parasites.

Coevolutionary relationship between helminth diversity and MHC class II polymorphism in rodents.

Parasite-mediated selection on major histocompatibility complex (MHC) genes has mainly been explored at the intraspecific level, although many molecular studies have revealed trans-species polymorphism. Interspecific patterns of MHC diversity might reveal factors responsible for the long-term evolution of MHC polymorphism. We hypothesize that host taxa harbouring high parasite diversity should exhibit high levels of MHC genetic diversity. We test this assumption using data on rodent species and their helminth parasites compiled from the literature. Controlling for similarity due to common descent, we present evidence indicating that high helminth species richness in rodent species is associated with increased MHC class II polymorphism. Our results are consistent with the idea that parasites sharing a long-term coevolutionary history with their hosts are the agents of selection explaining MHC polymorphism.

Helminth species diversity of mammals: parasite species richness is a host species attribute.

Studies investigating parasite diversity have shown substantial geographical variation in parasite species richness. Most of these studies have, however, adopted a local scale approach, which may have masked more general patterns. Recent studies have shown that ectoparasite species richness in mammals seems highly repeatable among populations of the same mammal host species at a regional scale. In light of these new studies we have reinvestigated the case of parasitic helminths by using a large data set of parasites from mammal populations in 3 continents. We collected homogeneous data and demonstrated that helminth species richness is highly repeatable in mammals at a regional scale. Our results highlight the strong influence of host identity in parasite species richness and call for future research linking helminth species found in a given host to its ecology, immune defences and potential energetic trade-offs.