Abstract:  In this study, we investigated the molecular evidence of Trypanosoma evansi  in wild rodents from Cambodia, Lao PDR and Thailand. Between November 2007 and June 2009, 1664 rodents were trapped at eight sites representative of various ecological habitats. Of those animals, 94 were tested by direct microscopic blood examination, 633 using the Card Agglutination Test for Trypanosomes (CATT/T. evansi ) and 145 by Polymerase Chain Reaction (PCR) with two sets of primers: TRYP1 (amplifying ITS1 of ribosomal DNA of all trypanosomes) and TBR (amplifying satellite genomic DNA of Trypanozoon  parasites). Using TRYP1, based on the size of the PCR products, 15 samples from the three countries were positive for Trypanosoma lewisi  (two were confirmed by sequencing), and three were positive for Trypanozoon  (one was confirmed by sequencing and three by TBR primers); the specificity of the primers failed as rodent DNA was amplified in some cases. Using TBR, six samples were positive for Trypanozoon  (one was confirmed by sequencing); as T. evansi  is the only species of the Trypanozoon  sub-genus possibly present in Asian rodents, these results confirmed its presence in rodents from Thailand (Rattus tanezumi ) and Cambodia (R. tanezumi , Niviventer fulvescens  & Maxomys surifer ). Further investigations are necessary to establish the situation in Lao PDR. None of the 16 samples most strongly positive to the CATT proved to be positive for Trypanozoon  by PCR. The merits of the CATT for such studies were not confirmed. Studying the urban and rural circulation of these parasites in rodents will enable an evaluation of human exposure and infection risk, as human infections by T. evansi  were recently described in India and by T. lewisi  in India and Thailand. As sequencing PCR products is expensive, the development of new molecular and serological tools for rodents would be very useful.

Key words:  Trypanosoma evansi , Trypanosoma lewisi,  PCR, rodents, Cambodia, Lao PDR, Thailand

DOI: 10.1111/j.1865-1682.2012.01314.x

Abstract:  Black rats are major invasive vertebrate pests with severe ecological, economic and health impacts. Remarkably, their evolutionary history has received little attention, and there is no firm agreement on how many species should be recognized within the black rat complex. This species complex is native to India and Southeast Asia. According to current taxonomic classification, there are three taxa living in sympatry in several parts of Thailand, Cambodia and Lao People’s Democratic Republic, where this study was conducted: two accepted species (Rattus tanezumi , Rattus sakeratensis ) and an additional mitochondrial lineage of unclear taxonomic status referred to here as ‘Rattus  R3’. We used extensive sampling, morphological data and diverse genetic markers differing in rates of evolution and parental inheritance (two mitochondrial DNA genes, one nuclear gene and eight microsatellite loci) to assess the reproductive isolation of these three taxa. Two close Asian relatives, Rattus argentiventer  and Rattus exulans , were also included in the genetic analyses. Genetic analyses revealed discordance between the mitochondrial and nuclear data. Mitochondrial phylogeny studies identified three reciprocally monophyletic clades in the black rat complex. However, studies of the phylogeny of the nuclear exon interphotoreceptor retinoid-binding protein gene and clustering and assignation analyses with eight microsatellites failed to separate R. tanezumi  and R3. Morphometric analyses were consistent with nuclear data. The incongruence between mitochondrial and nuclear (and morphological) data rendered R. tanezumi /R3 paraphyletic for mitochondrial lineages with respect to R. sak- eratensis . Various evolutionary processes, such as shared ancestral polymorphism and incomplete lineage sorting or hybridization with massive mitochondrial introgression between species, may account for this unusual genetic pattern in mammals.

Key words :  incomplete lineage sorting, introgression, paraphyly, Rattus , recent speciation, species complex

DOI:  10.1111/mec.12149

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

Key words:  helminths, parasite species richness, murid rodents, habitat, anthropization, Lao PDR

DOI:  10.1017/S0022149X13000187

Abstract – During a study of the helminth fauna of 1,643 rodents trapped along the Mekong River (Thailand, Lao People’s Democratic Republic and Cambodia) in 2008–2011, the spirurid nematode Physaloptera ngoci Le-Van-Hoa,1961 was recovered with an overall prevalence of 2.8%. Based on the original description, it was identified in nine of 23 different Murinae host species and is here reported for the first time from these three countries. A scanning electron microscopy study provides additional morphological data.

Key words:  Helminths / Physaloptera ngoci  / Rodents / Thailand / Lao People’s Democratic Republic / Cambodia.

DOI  http://dx.doi.org/10.1051/parasite/2013023

Abstract:  The presence of gastrointestinal helminths (GI helminths) was investigated among 725 murid rodents, trapped in various habitats of Nan, Loei and Buri Ram Provinces, Thailand. The study revealed 17 species of rodents infected with  21  species  or  taxonomic  groups  of  parasites  (3  trematodes,  3  cestodes,  14 nematodes and 1 acanthocephalan). The overall prevalence of infection was 57.7% (418 / 725).  Of  the  gastrointestinal  (GI)  helminths,  the  dominant  parasitic  group was members of the family Trichostrongylidae (24.3%), followed by the cestodes Raillietina sp (17.1%) and  Hymenolepis diminuta (8.6%) and the nematode  Syphacia muris (8.6%). The GI helminthic infection rates were highest in  Mus caroli (81.8%), Mus cervicolor (76.5%), Leopoldamys edwardsi (75.0%), Bandicota indica  (71.5%) and Bandicota savilei  (71.4%). Highest rodent species richness (RSR) and helminth spe -cies richness (HSR) rates were found in Loei, followed by Nan and Buri Ram. The  helminth prevalence rate was higher in rodents from Nan, followed by rodents from Loei and Buri Ram. Rodents from irrigated fields had the highest infection rates followed by rodents from upland or dry agricultural areas, forests and do -mestic habitats. Raillietina sp,  Rodentolepis nana (syn.  Hymenolepis nana),  Hymenol -epis diminuta ,  Moniliformis moniliformis  and Cyclodontostomum purvisi, considered zoonotic  parasites,  were  mainly  found  in  rodents  from  domestic  habitats  and lowland irrigated fields.

Key words:   gastrointestinal helminths, rodents, habitat, Thailand

Accession number:  ISI:000299861900004

Abstract: Background: Comparative analysis, which aims at investigating ecological and evolutionary patterns among species, may help at targeting reservoirs of zoonotic diseases particularly in countries presenting high biodiversity. Here, we developed a simple method to target rodent reservoirs using published studies screening microparasite infections. Methods: We compiled surveys of microparasites investigated in rodents trapped in Thailand. The data comprise a total of 17,358 rodents from 18 species that have been investigated for a total of 10 microparasites (viruses, bacteria and protozoans). We used residual variation of microparasite richness controlled for both rodent sample size and pathogens’ screening effort to identify major rodent reservoirs and potential risky habitats. Results: Microparasite species richness was positively related to rodent sample size and pathogens’ screening effort. The investigation of the residual variations of microparasite species richness showed that several rodent species harboured more pathogens than expected by the regression model. Similarly, higher pathogen richness than expected was observed in rodents living in non-flooded lands, forests and paddy fields. Conclusion: Our results suggest to target some rodent species that are not commonly investigated for pathogen screening or surveillance such as R. adamanensis or B. savilei , and that non-flooded lands and forests should be more taken into caution, whereas much surveys focused on paddy rice fields and households.

Keywords: microparasite richness; rodents; Southeast Asia; zoonosis; habitat; prioritization

DOI: http://dx.doi.org/10.3402/iee.v2i0.18637

Herbreteau et al., IEE, 2012

Abstract:  We investigated infection of rodents and shrews by Leptospira  spp. in two localities of Cambodia (Veal Renh, Kaev Seima) and in four types of habitat (forests, non-flooded lands, lowland rain-fed paddy fields, houses) during the wet and the dry seasons. Habitat preference was common, and rodent and shrew species were found only in houses or in rain-fed paddy fields or in forests. Among 649 small mammals trapped belonging to 12 rodent species and 1 shrew species, 71 of 642 animals tested were carriers of Leptospira  according to the 16S ribosomal RNA marker used. Rodent infection was higher in low-slope locations, corresponding to rain-fed paddy fields, especially in the rainy season and in Kaev Seima. Rodents (Rattus exulans ) and shrews (Suncus murinus ) inhabiting households showed significantly low levels of infections, whereas rodents living in and near to forests (shrubby wasteland, orchards) showed high levels of infection.

Key words:   gastrointestinal helminths, rodents, habitat, Thailand

DOI:  10.4269/ajtmh.2012.11-0349

Abstract:  Among 1341 blood samples from rodents trapped in Southeast Asia between 2008 and 2010, we found a prevalence of Bartonella  infection ranging from 9.6 to 11.9%. Bartonella  species identified (143 isolates) include B. elizabethae, B. coopersplainsensis, B. phoceensis, B. queenslandensis, B. rattimassiliensis, B. tribocorum  and three new putative Bartonella  species. 

Abstract:  A large number (828) of rodents belonging to nine genera (Bandicota , Berylmys , Chiropodomys , Hapalomys , Leopoldamys , Maxomys , Mus , Niviventer  and Rattus ) were trapped in four Thai provinces between 2008 and 2010. A new species of Protospirura  (Nematoda: Spiruridae) was identified and described. Protospirura siamensis  n. sp. was found in 10 rodent species from the four Thai provinces surveyed. The new species can be distinguished from known species of the genus by the arrangement of the papillae on the male and the morphology and length of the spicules. This is the first species of Protospirura  to be described from South-East Asia.
DOI:  10.1007/s11230-012-9343-1

Short Communication

Veciana et al._CJNH_2012

Abstract:   In order to evaluate the circulation of hantaviruses present in southeast Asia, a large scale survey of small mammal species was carried out at seven main sites in the region (Cambodia, Lao People's Democratic Republic, and Thailand). Small scale opportunistic trapping was also performed at an eighth site (Cambodia). Using a standard IFA test, IgG antibodies reacting to Hantaan virus antigens were detected at six sites. Antibody prevalence at each site varied from 0 to 5.6% with antibodies detected in several rodent species (Bandicota indica, B. savilei, Maxomys surifer, Mus caroli, M. cookii, Rattus exulans, R. nitidius, R. norvegicus, and R. tanezumi ). When site seroprevalence was compared with site species richness, seropositive animals were found more frequently at sites with lower species richness. In order to confirm which hantavirus species were present, a subset of samples was also subjected to RT-PCR. Hantaviral RNA was detected at a single site from each country. Sequencing confirmed the presence of two hantavirus species, Thailand and Seoul viruses, including one sample (from Lao PDR) representing a highly divergent strain of Seoul virus. This is the first molecular evidence of hantavirus in Lao PDR and the first reported L segment sequence data for Thailand virus.

Key words:   hantavirus, southeast Asia, rodents, serology, phylogeny, seoul virus variant

DOI:   10.1007/s10393-011-0725-7

Abstract: Parasite species loads are expected to be higher in the tropics and higher parasite species richness to have cumulative effects on host physiology or demography. Despite being regularly assumed or predicted, empirical evidence on species-latitude patterns is scarce or contradictory and studies on the impacts of concomitant infections have mainly been done at host intra-specific level. Broad generalizations are then very hard, if not spurious.

By focusing on rodent species and their non-eukaryotic microparasites (i.e. viruses and bacteria), we investigated, using a comparative approach, microparasite species richness across rodent species according to the latitude where they occur. We also explored the links between rodents' reproductive traits, latitude and microparasite species richness.

We find for the first time in rodents that virus species richness increases towards tropical latitudes, and that rodent litter size seems to decrease when microparasite species richness increases independently from the latitude. These results support the hypotheses that rodent species in the tropics effectively harbour higher parasite species loads, at least in terms of species richness for viruses, and that parasite species richness influences rodent life-history traits. Although some other factors, such as seasonality, were not taken into account due the lack of data, our study stresses the idea that chronic microparasite infections may have detrimental effects on their rodent host reservoirs, notably by affecting litter size.

Keywords:  microparasite species richness, virus, bacteria, rodents, latitude, life-traits, litter size, comparative analysis.

DOI: 10.1111/j.1600-0706.2011.19314.x

Abstract:  Field parasitological studies consistently demonstrate the reality of polyparasitism in natural systems. However, only recently, studies from ecological and evolutionary fields have emphasised a broad spectrum of potential multiple infections-related impacts. The main goal of our review is to reunify the different approaches on the impacts of polyparasitism, not only from laboratory or human medical studies but also from field or theoretical studies. We put forward that ecological and epidemiological determinants to explain the level of polyparasitism, which regularly affects not only host body condition, survival or reproduction but also host metabolism, genetics or immune investment. Despite inherent limitations of all these studies, multiple infections should be considered more systematically in wildlife to better appreciate the importance of parasite diversity in wildlife, cumulative effects of parasitism on the ecology and evolution of their hosts.

Keywords:   Wildlife, polyparasitism, multiparasitism, coinfections, parasite diversity, life-history traits.

DOI: 10.3402/iee.v1i0.7346

Bordes and Morand, Inf Ecol and Epid, 2011

Abstract:  Species richness of parasite assemblages varies among host species. Earlier studies that searched for host-related determinants of parasite diversity mainly considered host traits that affect the probability of host encounter with parasites, whereas host traits related to defensibility against parasites have rarely been investigated. From the latter perspective, evolutionary investment in “expensive” tissue or organs (like testes or brain) may trade off against energetically costly anti-parasitic defences. If so, richer parasite assemblages are expected in hosts with larger testes and brains. We studied the relationships between testes and brain size and diversity of parasites (fleas, gamasid mites and helminths) in 55 rodent species using a comparative approach and application of two methods, namely the method of independent contrasts and generalized least-squares (GLS) analysis. Both phylogenetically correct methods produced similar results for flea and helminth species richness. Testes size positively correlated with flea and helminth species richness but not gamasid mite species richness. No correlation between brain size and species richness of any parasite group was found by the method of independent contrasts. However, GLS analysis indicated negative correlation between brain size and mite species richness. Our results cast doubt on the validity of the expensive tissue hypothesis, but suggest instead that larger testes are associated with higher parasite diversity via their effect on mobility and/or testosterone-mediated immunosuppression.

Keywords:   Expensive tissue hypothesis, Brain, Parasites, Rodents, Species richness.

DOI: 10.1007/s00442-010-1743-9

Abstract: At the end of the 20th century the unique taxonomically enigmatic entity called Pneumocystis carinii was identified as a heterogeneous group of microscopic Fungi, constituted of multiple stenoxenic biological entities largely spread across ecosystems, closely adapted to, and coevolving in parallel with, mammal species. The discoveries and reasoning that led to the current conceptions about the taxonomy of Pneumocystis at the species level are examined here. The present review also focuses on the biological, morphological and phylogenetical features of Pneumocystis jirovecii, Pneumocystis oryctolagi, Pneumocystis murina, P. carinii and Pneumocystis wakefieldiae , the five Pneumocystis species described until now, mainly on the basis of the phylogenetic species concept. Interestingly, Pneumocystis organisms exhibit a successful adaptation enabling them to dwell and replicate in the lungs of both immunocompromised and healthy mammals, which can act as infection reservoirs. The role of healthy carriers in aerial disease transmission is nowadays recognized as a major contribution to Pneumocystis circulation, and Pneumocystis infection of nonimmunosuppressed
hosts has emerged as a public health issue. More studies need to be undertaken both on the clinical consequences of the presence of Pneumocystis in healthy carriers and on the intricate Pneumocystis life cycle to better define its epidemio-logy, to adapt existing therapies to each clinical context and to discover new drug targets.

Key words: Pneumocystis spp.; phylogenetic species concept; life cycle; epidemiology.

DOI: 10.1111/j.1567-1364.2010.00698.x

Abstract:  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.

Keywords:   Notocotylus , Trematoda, Digenea, Notocotylidae, Rattus losea , lesser rice field rat, Thailand

Accession number: ISI:000289396100004

Abstract:  Trypanosoma lewisi  is a mild or non-pathogenic parasite of the sub-genus Herpetosoma  transmitted by fleas to rats. In a previous study we described pan-trypanosome specific primers TRYP1 which amplify the ITS1 of ribosomal DNA by hybridizing in highly conserved regions of 18S and 5.8S genes. These primers proved to be useful for detecting T. lewisi  DNA in laboratory rats, but a recent large scale survey in wild rodents demonstrated a lack of specificity. In the present study, we designed and evaluated mono-specific primers LEW1S and LEW1R, for the detection and identification of T. lewisi  by a single-step PCR. These primers were designed inside the highly variable region of the ITS1 sequence of T. lewisi  ribosomal DNA. The product size of 220 bp is specific to T. lewisi . The sensitivity limit was estimated between 0.055 and 0.55 pg of DNA per reaction, equivalent to 1–10 organisms per reaction. All the PCR products obtained from 6 different T. lewisi  isolates were more than 98% similar with each other and similar to the sequences of T. lewisi  already published in Genbank. All DNA of 7 T. lewisi  stocks from China gave the specific 220 bp product. We showed that LEW1S and LEW1R primers enabled sensitive detection and identification of T. lewisi  infection in laboratory and wild rats. This assay is recommended for monitoring T. lewisi  infections in rat colonies or for studying infections in the wild fauna. An absence of cross reaction with human DNA means that these primers can be used to investigate atypical trypanosome infections in humans. Given the risk of T. lewisi  infection in human, we believe that these primers will be beneficial for public health diagnosis and rodents investigation programmes.

Key words:  Trypanosoma lewisi ; PCR; ITS1; Ribosomal DNA; Primers; Rattus  sp.

DOI:  10.1016/j.meegid.2011.04.030

Abstract: Domestic and wild rodents known as the most abundant and diversified order of mammals have a key role in the ecological food chain and also in the transmission of parasites and pathogens to other animals. While foraging on the ground, they can get infected by Toxoplasma gondii, a protozoan parasite, which is the  causative agent of toxoplasmosis. Therefore, they serve as intermediate hosts of T. gondii and can transmit it to their predators. To assess their role in the maintenance of T. gondii lifecycle in Thailand, we sampled rodents in a range of biotopes representative of the high biodiversity and conducted a serological survey with latex agglutination
test to detect anti-T. gondii antibodies. Overall, 21 of 461 (4.6%) rodents had diagnostically significant antibody titers (cutoff, 1:64). Every species with at least 37 individuals captured tested positive, confirming the wide range of potential mammalian hosts of toxoplasmosis. None of the ecological traits (sex, maturity, morphology,
season, or habitat) was found significant to predict the susceptibility to T. gondii both univariately and in a multivariate analysis. However, high prevalences were reported in either forested or anthropized areas. This survey constitutes the first confirmed serological investigation of T. gondii in rodents in Thailand. The rarity of both domestic and wild felids in Thailand emphasizes the importance of rodents in maintaining T. gondii, and questions the involvement of other carnivores in the life cycle.

Key words:  Ecology, Murinae, Rattus, Rodent, T. gondii , Toxoplasmosis.

DOI:  10.1089/vbz.2009.0238

Abstract: Leopoldamys neilli is a threatened murine rodent species endemic to limestone karsts of Thailand. We have studied the phylogeography of L. neilli using two mitochondrial markers (cytb, COI) and one nuclear fragment (bfibr), in order to assess the influence of its endemicity to karst habitat. One hundred fifteen individuals of L. neilli were collected in 20 localities throughout the geographic range of this species in Thailand. Our study revealed strong geographic structure of the mtDNA genetic diversity: six highly differentiated, allopatric genetic lineages were observed in our dataset. They exhibit a very high degree of genetic divergence, low gene flow among lineages and low levels of haplotype and nucleotide diversities within lineages. Our results suggest that L. neilli ’s populations are highly fragmented due to the scattered distribution of its karst habitat. The most divergent lineage includes the populations from western Thailand, which have been separated from the other genetic lineages since at least the Early Pleistocene. The other lineages are more closely related and have diverged since the Middle Pleistocene. This study revealed an unexpected high level of genetic differentiation within L. neilli and highlighted the high endemicity of this species to limestone karsts. Our results enhance the importance of protecting limestone habitats to preserve not only the species but also intraspecific diversity.

Keywords:  Southeast Asia, Leopoldamys neilli , Limestone karsts, Conservation, Phylogeography, Intraspecific diversity

DOI: 10.1007/s10592-011-0248-3

Abstract:  Leopoldamys neilli is a threatened murine rodent species endemic to limestone karsts of Thailand. Twelve microsatellite loci were identified using the method of microsatellite-enriched libraries. Polymorphism was assessed in samples (N = 62) from four geographically distinct populations in Thailand. Number of alleles per locus ranged from 9 to 15 (average 11.6). Observed and expected heterozygosities varied from 0.28 to 1.0 and from 0.44 to 0.91, respectively. There was no evidence for linkage disequilibrium, however, four loci showed evidence of departure from Hardy–Weinberg equilibrium in one population. Presence of null alleles was not detected in all the 12 loci. These first microsatellites primers developed for L. neilli will provide information on the fine-scale genetic structure of this threatened species and will help in the development of future conservation policies.

Keywords: Leopoldamys neilli , Murine rodent, Microsatellite, Multiplex, Genetic structure, Southeast Asia

DOI: 10.1007/s12686-011-9391-x

Abstract: Two morphological forms of black rats (Rattus  cf. rattus ) were found living in sympatry in high-altitude dense forests of the Nilgiri Mountains, South India. The 1st one, often brown- or gray-bellied, also is found commensal in lowland settlements and represents Rattus rattus  cf. rufescens  (Gray 1837), with a diploid number (2N) of 38 chromosomes. The 2nd form, which has most often a pure white belly, has 2N  =  42 chromosomes and is referable to Rattus r. satarae  Hinton, 1918, based on morphological comparison with the holotype. A multidisciplinary study indicates that these 2 forms are characterized by clear-cut differences in biochemistry (electrophoresis of homologous isozymes), molecular sequences (mitochondrial and nuclear DNA), and chromosomes (detailed banding analysis). All these data, coupled to diagnostic morphological characteristics, support the hypothesis that Rattus satarae  and Rattus rattus  are separate, sympatric species, with no gene flow between them. Their similar external morphology is interpreted as the result of convergence through occupying the same ecological niche.

Keywords:  cryptic species, Rattus , rodent, South India.

DOI: 10.1644/10-mamm-a-033.1

Abstract:  Parasite diversity is hypothesized to act on host life-history traits through investment in immunity. In order to incorporate the diversity of the parasite community that an individual host or a host species may face, two indices can be used: Taxonomic Species Richness and Taxonomic Entropy, where the taxonomic information is incorporated with the taxonomic weight. We tested whether these indices correlate with several morphological traits potentially implicated in immune defence and in reproduction, using data on gastrointestinal helminths and their rodent hosts sampled in Southeast Asia. We found no relationship between parasite diversity indices and either spleen mass or testes size at the intraspecific level, i.e. at the level of individuals. At the interspecific level, we found no relationship between the parasite diversity indices and testes size. However, we found that female spleen mass is significantly influenced by the specific species richness of parasites, whereas male spleen mass is influenced by individual mean parasite diversity indices. We concluded that female spleen mass may have evolved in response to gastrointestinal helminth pressure acting at species levels, while in males, the individual spleen mass could be constrained by other factors, such as the blood storage function of the spleen.

Key words:   Rodents, Southeast Asia, gastrointestinal helminths, parasite species richness, taxonomic index, taxonomic weight, comparative analysis, spleen mass, testes size.

DOI:  10.1017/S003118201100028X

{Ponlet, 2011 #1289}

Abstract:  Orientia tsutsugamushi , an obligate intracellular bacterium closely related to the genus Rickettsia , is the causative agent of scrub typhus, a major cause of febrile illness in rural areas of Asia-Pacific region. Scrub typhus is transmitted by the bite of infected mites of the genus Leptotrombidium . The region of the 56-kDa TSA gene spanning from variable domain I (VDI) to variable domain IV (VDIV) was sequenced and used for genotyping 77 O. tsutsugamushi samples from human patients confirmed with scrub typhus from 2001 to 2003 and 2009 to 2010 in different regions of Thailand. These sequences were also compared to previously published 56-kDa TSA sequences. Only 4 genotypes out of 8 previously reported in Thailand were identified, i.e. Karp, JG-v, TA763 and Kato, respectively. Two strains were not associated with known genotypes but were closely related to Taiwanese strains. The Karp genotype was confirmed as the predominant clade. The JG-v and TA763 genotypes, in contrast to other studies, also were found. The genotype TA716 was not found, except for one strain previously described.

Key words: Orientia tsutsugamushi , 56-kDa type specific antigen gene, phylogenetic analysis, genetic diversity, Thailand

DOI: S1567-1348(11)00221-8 [pii]
10.1016/j.meegid.2011.06.008

Abstract: This work reports for the first time the presence of two Pneumocystis species in wild Rattus norvegicus  specimens from Thailand. Pneumocystis DNA was detected in 57.7% (15/26) wild rats without apparent association with typical pneumocystosis. Pneumocystis carinii was found alone in five rats (19.2%), Pneumocystis wakefieldiae  was detected alone in six rats (23.1%), and two rats were infected by both species (7.7%). In addition, a new P. wakefieldiae  variant sequence has been identified in three wild R. norvegicus specimens caught in the same geographical area. The high frequency of Pneumocystis in wild rats documented in this study and the apparent scarcity of severe pneumocystosis were consistent with an efficient circulation of rat Pneumocystis species in ecosystems.

Key words:  PCR, Pneumocystis spp, rat, wild fauna.

DOI:  JEU465 [pii]
10.1111/j.1550-7408.2009.00465.x

Abstract: The effect of habitat anthropization is investigated using a comparative analysis based on a literature survey of the gastrointestinal helminths of murid rodents described in Southeast Asia (SEA). The literature survey gave 30 references on helminth diversity concerning 20 murid rodent species. The diversity of helminths was high with a total of 13 species of cestodes, 15 species of trematodes, 29 species of nematodes and one species of acanthocephalans. The highest helminth species richness was found in Rattus tanezumi , Rattus norvegicus  and Rattus argentiventer , all these species were found in more human-dominated habitats (agricultural areas or human settlements). Helminth species richness was positively linked across rodent species to the level of the anthropization of the host environment from forests, agricultural areas to human settlements.

Key words:  Southeast Asia, rodents, parasite species richness, helminths, anthropogenic disturbances, comparative analysis

DOI:  10.1007/s00436-010-1955-2

Abstract: The presence of gastrointestinal helminths (GI helminths) was investigated in 68 Asian house rat (Rattus tanezumi ) trapped in various habitats as forests, upland, lowland agricultural areas and domestic places from northern and northeastern Thailand. The study revealed that rodents were infected with 11 species or taxonomic groups of parasites (2 cestodes, 8 nematodes and 1 acanthocephalan). The prevalence of infection was 66.2% (45 infected out of 68 rats). Among GI helminths, the dominant parasites were Trichostrongylidae (33.8%) followed by Raillietina sp. (20.6%), Syphacia muris (14.7%) and Hymenolepis diminuta (11.8%). The domestic habitats showed the highest prevalence of infection (23.5%) followed by upland (17.6), lowland (16.1%) and forests (8.8%). In the same way, helminth diversity was found highest in domestic place followed by upland, lowland and forests with 8, 7, 6 and 4 species or taxonomic groups respectively. The prevalence of parasite infection and helminth species richness of R. tanezumi were found to be higher in human living places than in wild habitats or agricultural areas. Host sex and maturity were not significantly found to influence the overall prevalence of helminth infection. Finally, the following parasites Raillietina sp., Hymenolepis diminuta and Moniliformis moniliformis , causes of potentially parasitic zoonoses, were also found in domestic habitats, which appear to be risky for human exposure to helminthiasis in this region.

Key words: gastrointestinal helminth, rodent, Rattus tanezumi , habitat, zoonoses, Thailand

Chaisiri et al., JTMP, 2010

Abstract: The  Great  Bandicoot  (Bandicota  indica ),  the  giant  sized-rat  is  commonly  found  in  lowland agricultural areas throughout South and Southeast Asia. It cause great damage to agricultural products and act  as  important  reservoir  of  many  rodent-borne  diseases.  The  present  study  revealed  the  gastrointestinal helminth  (GI  helminth)  examination  made  on  123 Bandicota  indica  (59  males  and  64  females;  72  adults and  51  juveniles)  captured  from  northern  and  northeastern  Thailand.  Two  cestodes  (Raillietina sp., Hymenolepis  diminuta ),  one  trematode  (Notocotylus  sp. ),  10  nematodes  (Trichuris  muris, Eucoleus sp., Aonchotheca  sp.,  Ganguleterakis  spumosa,  Syphacia  muris,  Physaloptera  sp.,  Protospiura  sp., Mastophorus sp., Cyclodontostomum purvisi, Trichostrongylidae ) and 1 Pentastomida were collected. The overall prevalence of infection was 71.54%  (88 infected out of 123  rodents).  The infection rate in males (74.58%)  was  higher  than  in  females  (68.75%).  In  the  same  way,  adult  rodents  (81.94%)  were  higher infection rate than in juveniles (56.86%). Among GI helminths, the dominant parasites were Raillietina sp. (60.97%)  followed  by  Ganguleterakis  spumosa   (15.45%),  Trichostrongylidae  (12.19%)  and  Syphacia muris  (8.94%).  The  cestodes,  Raillietina  sp.  and  Hymenolepis  diminuta  were  considered  as  cause  of parasitic zoonoses of medical important linked with Bandicota indica in this region.
Key words: Bandicota indica , Rodents, Gastrointestinal helminth, Thailand

Chaisiri et al., SPY, 2010

Abstract: Wildlife surveys rely on an accurate taxonomic framework. Identification tools used to reach this goal are not equivalent and may depend on several objectives and constraints, including sampling conservation difficulties, the invasiveness of the sampling techniques, sampling capacity, the relevance of the results, materials needed, the cost and the user time required in the field and laboratory. This article presents and discusses the advantages and limits of each identification tool used in the Ceropath (Community ecology of rodents and their pathogens in South East Asia) program to reach a fast and relevant identification of the rodents sampled. It is concluded that there needs to be a combination of the results from different methods, including the most recent ones, to achieve an improvement in taxonomic identification.

Key words: morphology, morphometry, cytotaxonomy, molecular phylogeny, barcoding

Chaval et al., 2010

Abstract:  Orientia tsutsugamushi , the causative agent of scrub typhus in South East Asia and Pacific, is an obligate intracellular bacterium closely related to the Rickettsia . The pathogen is transmitted to humans through the bites of infected larvae of trombiculid mites of the genus Leptotrombidium in which is maintained trough vertical transmission mechanism. The infection in rodents has been described in over 20 species. Scrub typhus is commonly confused with other tropical fevers and late diagnosis and treatment can lead to severe organ failures and a strain-dependent mortality rate of up to 50%. A MLST scheme associating seven core function genes: adk, lepB, lipA, lipB, secY, sodB and sucA was developed and validated on seven Cambodian strains detected in patients and two complete reference genomes from Korea and Japan. Sequence data were analyzed both with respect to sequence type (ST) diversity and DNA polymorphism. Differing trends were revealed. DNA polymorphism and phylogeny of individual gene loci indicated a significant level of recombination and genetic diversity. However, the ST distribution is clearly clonal and the clinical situation can be summarized by the formula: one patient, one strain, one ST. This contradiction is only apparent and is most likely the consequence of the unique life cycle of O. tsutsugamushi . The quasi exclusive vertical transmission mode in mites generates repeated bottlenecks and small-size populations and strongly limits genetic diversity. O. tsutsugamushi has developed specific mechanisms for generating genetic diversity which include recombination, duplication and conjugation. Recombination and other mechanisms for increasing genetic diversity are likely to occur in rodents which can act as maintenance hosts, although occurrence in mites cannot be excluded. Consequences for the epidemiology of scrub typhus are discussed.

Key words:  Orientia tsutsugamushi , scrub typhus, MLST, phylogeny, recombination, selective pressure, polymorphism, genetic diversity

DOI:  S1567-1348(10)00244-3 [pii]
10.1016/j.meegid.2010.08.015

Abstract:

Background

High-throughput sequencing technologies offer new perspectives for biomedical, agronomical and evolutionary research. Promising progresses now concern the application of these technologies to large-scale studies of genetic variation. Such studies require the genotyping of high numbers of samples. This is theoretically possible using 454 pyrosequencing, which generates billions of base pairs of sequence data. However several challenges arise: first in the attribution of each read produced to its original sample, and second, in bioinformatic analyses to distinguish true from artifactual sequence variation. This pilot study proposes a new application for the 454 GS FLX platform, allowing the individual genotyping of thousands of samples in one run. A probabilistic model has been developed to demonstrate the reliability of this method.

Results

DNA amplicons from 1,710 rodent samples were individually barcoded using a combination of tags located in forward and reverse primers. Amplicons consisted in 222 bp fragments corresponding to DRB exon 2, a highly polymorphic gene in mammals. A total of 221,789 reads were obtained, of which 153,349 were finally assigned to original samples. Rules based on a probabilistic model and a four-step procedure, were developed to validate sequences and provide a confidence level for each genotype. The method gave promising results, with the genotyping of DRB exon 2 sequences for 1,407 samples from 24 different rodent species and the sequencing of 392 variants in one half of a 454 run. Using replicates, we estimated that the reproducibility of genotyping reached 95%.

Conclusions

This new approach is a promising alternative to classical methods involving electrophoresis-based techniques for variant separation and cloning-sequencing for sequence determination. The 454 system is less costly and time consuming and may enhance the reliability of genotypes obtained when high numbers of samples are studied. It opens up new perspectives for the study of evolutionary and functional genetics of highly polymorphic genes like major histocompatibility complex genes in vertebrates or loci regulating self-compatibility in plants. Important applications in biomedical research will include the detection of individual variation in disease susceptibility. Similarly, agronomy will benefit from this approach, through the study of genes implicated in productivity or disease susceptibility traits.

DOI :10.1186/1471-2164-11-296

Abstract:

Background: Rodents are recognized as hosts for at least 60 zoonotic diseases and may represent a serious threat for human health. In the context of global environmental changes and increasing mobility of humans and animals, contacts between pathogens and potential animal hosts and vectors are modified, amplifying the risk of disease emergence. An accurate identification of each rodent at a specific level is needed in order to understand their implications in the transmission of diseases. Among the Muridae, the Rattini tribe encompasses 167 species inhabiting South East Asia, a hotspot of both biodiversity and emerging and re-emerging diseases. The region faces growing economical development that affects habitats, biodiversity and health. Rat species have been demonstrated as significant hosts of pathogens but are still difficult to recognize at a specific level using morphological criteria. DNA-barcoding methods appear as accurate tools for rat species identification but their use is hampered by the need of reliable identification of reference specimens. In this study, we explore and highlight the limits of the current taxonomy of the Rattini tribe.

Results: We used the DNA sequence information itself as the primary information source to establish group membership and estimate putative species boundaries. We sequenced two mitochondrial and one nuclear genes from 122 rat samples to perform phylogenetic reconstructions. The method of Pons and colleagues (2006) that determines, with no prior expectations, the locations of ancestral nodes defining putative species was then applied to our dataset. To give an appropriate name to each cluster recognized as a putative species, we reviewed information from the literature and obtained sequences from a museum holotype specimen following the ancient DNA criteria.

Conclusions: Using a recently developed methodology, this study succeeds in refining the taxonomy of one of the most difficult groups of mammals. Most of the species expected within the area were retrieved but new putative species limits were also indicated, in particular within Berylmys and Rattus genera, where future taxonomic studies should be directed. Our study lays the foundations to better investigate rodent-born diseases in South East Asia and illustrates the relevance of evolutionary studies for health and medical sciences.

DOI:  1471-2148-10-184 [pii]
10.1186/1471-2148-10-184

Pages_Rattini_BMC_Evol_Biol

Abstract: Organisms adapt and evolve in response to environmental changes. Current changes in the
environment occur at a rate and scale that are closer to those of mass extinction rather than of normal,
background extinction. The response of species to global changes will depend on their ability to disperse
and to acclimatize, as well as on their evolvability. The current view is that the high rate of current
environmental changes impedes the evolutionary processes of adaptation to new conditions. Rodents,
however, show a high potential to successfully adapt to changing environments over various time scales,
including very rapid responses thanks to various characteristics of their life history, traits and plasticity.
This paper briefly reviews the processes that allow rodents to respond to the challenges of changing
environments, from the instantaneous plastic response to the paleontological perspective of long term
evolution. Rodents indeed include very opportunistic and highly evolvable species, which may
successfully overcome the ongoing changes, although some specialist species will inevitably be the
victim of the adjustment of the communities to the human-driven modification of their environments.

Key words: rodents, community, changing environment, adaptation, evolution

Auffray et al., KUJ, 2009

Abstract: Karyotypes of 18 rodent species collected in various localities in Thailand were analysed as part of an epidemiological survey of the region using conventional cytogenetic techniques. The aim was to re-assess the reliability of karyotype-based diagnoses of Thai rodents using an updated taxonomic framework. The species examined include Menetes berdmorei  (Sciuridae), Mus caroli , Mus cervicolor and Mus cookii , Hapalomys delacouri , Chiropodomys gliroides , as well as several representatives of most of the lineages of the Rattini tribe, that is Rattus exulans , Rattus losea , Rattus tanezumi , Leopoldamys edwardsi , Leopoldamys neilli , Maxomys surifer , Niviventer fulvescens , Berylmys berdmorei , Berylmys bowersi , Bandicota indica  and Bandicota savilei  (Muridae). The first descriptions of G- and/or C-banding karyotypes are provided for several of these, that is, B. savilei , L. edwardsi , M. surifer , B. berdmorei , B. bowersi , N. fulvescens  and H. delacouri . Although largely in agreement with available data, our findings on chromosome morphology differ slightly from those published for L. edwardsi , M. surifer , B. savilei  and the two Berylmys  species, B. berdmorei and B. bowersi . In addition, we document the novel finding of B-chromosomes in the genera Berylmys , Bandicota  and the emblematic Mus . Importantly, few species-specific chromosomal characteristic could be identified within most of the genera investigated in our study and, in contrast to previous claims, the usefulness of karyotypes for diagnosing these Asian murid species appears to be limited.

Key words:  cytotaxonomy, systematics, sibling species, Rattini.

DOI: 10.1111/j.1469-7998.2009.00588.x

Abstract:  Arenaviruses and hantaviruses circulate among the rodent populations of southeast Asia, and
can occasionally be transmitted to humans. The latter virus has been identified in human patients in
southeast Asia, although the former has not. The case fatality rate due to hemorrhagic fever with renal
syndrome (HFRS), caused by hantaviruses and carried by murine rodents, varies between 2–12%, while
the case fatality rate due to the arenaviral lymphocytic choriomeningitis virus (LCMV) is lower than
1%. Great care must be taken to avoid infection in pregnant women by LCMV, where serious
complications can occur. At present, treatment other than supportive therapy is unavailable for LCMV.
A range of vaccines exists in Asia, or are under development for the prevention of hantavirus infection,
while ribavirin can help in the early phase of an acute illness.
With changing climates and land use and rapidly increasing globalization, it is likely that the
situation regarding these zoonotic viruses will change, resulting in an increase in human infections. Few
studies have been carried out in this region, particularly in terms of LCMV. More are needed to establish
the rates of infection by these agents (and for other potential rodent-borne zoonoses), both in their
rodent hosts and in humans, so that they can be used as a baseline to monitor any changes that may
occur.

Key words:  arenavirus, hantavirus, rodents, southeast Asia, zoonoses

Blasdell et al., KUJ, 2009

Abstract: Animals often suffer from multiple parasite attacks in natural conditions (i.e., polyparasitism). The community of these parasites, which simultaneously or sequentially infest given host species, has rarely been investigated as a parasitic pressure per se. From this perspective, and despite the impressive number of immunoecological or comparative studies, the impacts of polyparasitism on immune responses are far from being appreciated. Focusing on helminths across a wide range of mammalian species and using a phylogenetic comparative method, we show, for the first time, that an increase in the number of helminth parasite species is positively correlated with an increase in basal immune investment (estimated by the counts of white blood cells) across mammal species. After discussing inherent limits of this comparative approach, we put this result in the evolutionary perspective of multiple parasitic infestations.

Key words:  parasite species richness, disease risk, infections, diversity, ecology, system, hosts, polymorphism, communities, assemblages.

DOI:  10.1007/s00436-009-1623-6

Abstract: Most free-living animals in their natural environments are hosts for a large diversity of parasites at individual, population or species level. Ongoing global changes are dramatically affecting the structure of the parasite diversity hosts may face, mostly through the alteration of the geographical distributions of parasites in relation to climate change, habitat fragmentation or bioinvasions (Daszak et al. 2000). Hosts are facing new parasites, which gives rise to the building of new communities of parasite species. In the face of these novel and increased risks of exposure to new parasites, it becomes crucial to improve our knowledge about the cumulative effects of co-infections on various host traits. Emphasizing the importance of polyparasitism in host populations could also improve our knowledge about the role of parasitism in ecosystems (Kuris et al. 2008).

Host-parasite interactions have been intensively investigated mostly on single host species/single parasite species, whereas hosts are typically infected by multiple parasite species. After emphasizing the importance of parasite diversity in natural populations, we focus on mammals and discuss the main limits of ‘one host/one parasite system’ approaches when estimating parasitic pressures. Then, we give recent arguments that support the hypothesis that parasite diversity per se exerts a strong selective pressure on hosts. We also discuss some inherent problems concerning the estimation of this potential underestimated metric of parasite pressures. Finally, we propose several directions to progress in our knowledge on the effects of parasitic pressures in natural systems.

Key words:  gamasid mite assemblages, small mammalian hosts, species richness, willow ptarmigan, body condition, life-history, population, wild, ecology, infection

DOI:  10.1111/j.1600-0706.2008.17169.x

Abstract: Parasite diversity among and within host species is not solely the result of random processes; rather, it depends on a suite of physiological or ecological host traits as well as environmental factors. Because most macroparasites exhibit life cycles that include infective stages off the definitive host and that rely on host movements for dissemination, parasite acquisition by a host depends largely on hosts being present in a given area where and when infective stages are present. Consequently, host ranging pattern may have a major influence on parasite diversity. Larger home range size is hypothesized to be associated with higher parasite species richness because hosts living in large home ranges should encounter a greater diversity of habitats and other host individuals, which in turn may favor infection by a great diversity of parasite species. By focusing on helminths in wild mammals, we show that an increase in home range area does not lead to an increase in parasite diversity in ungulates and, moreover, that it is associated with a decrease in parasite species richness in carnivores and in glires (rodents and lagomorphs). We also show that home range size is negatively correlated with host density in mammals after correcting both variables for host body mass. We discuss these results from an epidemiological perspective.

Key words:  parasite diversity, home range, density, mammals, behavior, epidemiology.

DOI:  10.1086/597227

Abstract: Rodents are a significant problem to farmers in upland agricultural systems in Lao PDR. They are considered as the second most important pest after insects because they are the least controlled. There is little known about the factors that influence the breeding activity or changes in population numbers of the main rodent pest species in Lao PDR. There are a minimum of 21 species of murid rodents in Lao PDR, with six considered as important crop pests, among them being Rattus rattus . The other species generally cause little crop damage and are important for their conservation value in the upland forests. Trapping data revealed that the population abundance and breeding activity of rats changed over time in response to the availability of food resources. Peaks in population abundance in the field occurred during the harvest of wet season crops. Rodents then moved into village habitats, where population abundance was high during the fallow and early growing stages. Breeding activity was evident at all stages in the village, with a peak during the fallow stage, when abundant food was available in village stores. Little breeding was observed in the field during the fallow period, increasing to only moderate levels during the growing and harvesting stages. The village habitat is considered as an important habitat for rodents. Management needs to be focussed on limiting the movement of rodents between villages and fields and this needs to be conducted prior to the onset of breeding activity in the field.

Key words: abundance, breeding, movements, Rattus rattus , rice, management

Douangboupha et al., KUJ, 2009

Abstract: Rodents have proven to be of increasing importance in transmitting diseases to humans in recent decades, through the emergence of worldwide epidemics and, in Thailand, through the emergence of leptospirosis and scrub typhus. Investigations of parasites and pathogens in murine rodents have helped to describe the implication of the main species and understand the different ways of transmission. From wild to anthropized habitats, rodents can be reservoirs, hosts or vectors of infectious organisms. Related species can react very differently to the same pathogens, with pivotal implications for the understanding of their natural circulation. Scrub typhus is transmitted to humans through the bites of trombiculid mites that have previously fed on infected rodents, generally occurring in wild habitats. Leptospirosis can affect people without any direct contact with infected rodents, but by indirect spread in agricultural areas. Parasitic diseases, such as toxoplasmosis and trypanosomiasis benefit from the proximity of rodents to domesticated animals to jump from one vector to another before reaching humans. By occupying almost all biotopes and by rapidly adapting to environmental changes, rodents are fundamental in the maintenance and transmission of an impressive number of infectious organisms to humans.

Key words: rodents, zoonoses, parasites, toxoplasmosis, trypanosomiasis

Jittapalapong et al., KUJ, 2009

Abstract: The Centre for Thai National Reference Collections (CTNRC) was officially established in 1965, but animal collections in Thailand had been continuously conducted long before this time. This paper gives an historical review of the main steps leading to the constitution of the current collections under the administration of TISTR, with a focus on the rodent collection, which represents about one fifth of the whole mammal specimens. An inventory of the species and genera represented is given. Statistics representing the sampling effort in the different Thai provinces are given. The paper concludes with considerations on the current and future needs and the means necessary to develop and support the efforts of the CTNRC.

Key words : CTNRC, ASRCT, NSM, rodent collection

Waengsothorn et al., KUJ, 2009

Abstract: 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.

Key words: parasite species richness, helminths, repeatability.

DOI:  10.1017/S0031182008005040

Abstract: Hantaviruses belong to the Bunyaviridae family. While usually hosted by wild mammals, they are potentially pathogenic for humans, and several serologically distinct groups associated with different syndromes have been identified. Yet, investigations have mostly been conducted where human infections by hantaviruses constitute a real andwell-identified public health problem, i.e., the holarctic and neotropical areas. Some hantaviruses have also been described from a Suncus murinus in India and a Bandicota indica in Thailand. In addition, recent investigations in Cambodia revealed new Hantavirus types. More recently, two new Hantavirus species were described: Sangassou from a Hylomyscus simus , and Tanganya from a Crocidura theresae , both from Africa (Guinea), thus strongly questioning the current views about geographic range, evolution, and epidemiology of hantaviruses. In such a framework, we have conducted a survey of Hantavirus diversity in Southeast Asia which allows us to isolate the Thailand virus and address questions about the taxonomy of their rodent hosts. Here we present a molecular analysis of representatives of all currently known Hantavirus species, thus allowing the comparison between the newly described ones with a large range sample of rodent hantaviruses. Our results clearly point to the presence of a particular lineage of hantaviruses in Southeast Asia. It also strongly suggests that new viruses, additional mammalian hosts and different related syndromes in humans are likely to be discovered in the near future, particularly in Southeast Asia and in Africa, where Muridae rodents are highly diversified. Furthermore, additional work is also urgently needed to investigate the hantaviruses associated with Crociduridae and Soricidae.

Key words:   rodent-borne; shrew-borne; hantaviruses; Thottapalayam ; S gene; phylogeny; Bayesian analysis; biogeography; coevolution.

DOI:  10.1196/annals.1428.064

Abstract: 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.

Key words:  Trypanosoma ; Herpetosoma ; Salivaria; Rodents; Habitat; Internal transcribed spacer 1 (ITS-1).

DOI:  10.1016/j.meegid.2007.08.002