Borrelia is a genus of spirochetal bacteria with several species known to cause disease in humans. The distribution of Borrelia has rarely been studied in Thailand. In this study, a retrospective ...survey of Borrelia was conducted in ticks and wild rodents to better characterize the prevalence, diversity, and distribution of Borrelia across Thailand. Several pools of DNA from tick samples were positive for Borrelia spp. (36/258, 13.9%). Borrelia theileri/B. lonestari was found in 17 tick samples (16 pools of Haemaphysalis bandicota and 1 pool of Rhipicephalus sp.), and Borrelia yangtzensis was found in 8 tick samples (2 pools of H. bandicota and 6 pools of Ixodes granulatus). Borrelia spp. were detected at low prevalence levels in rodent tissue samples (24/2001, 1.2%), with 19 identified as B. theileri or B. lonestari and 5 identified as B. miyamotoi. Several geographic and species-specific infection trends were apparent, with Ixodes ticks infected with B. yangtzensis and Haemaphysalis and Rhipicephalus ticks infected with both B. yangtzensis and B. theileri/B. lonestari. Notably, B. yangtzensis showed a similar geographic distribution to B. miyamotoi, which was identified in new areas of Thailand in this study. The flagellin gene sequence from B. miyamotoi was more similar to European (99.3–99.9%) than Japanese (96.9–97.6%) genotypes. This study greatly expands the knowledge of Borrelia in Thailand and identified several Borrelia species for the first time. It also found several ticks and rodents infected with the pathogen that were not previously known to carry Borrelia.
In this study, we used a metagenomic approach to analyze bacterial communities from diverse populations (humans, animals, and vectors) to investigate the role of these microorganisms as causative ...agents of disease in human and animal populations. Wild rodents and ectoparasites were collected from 2014 to 2018 in Nan province, Thailand where scrub typhus is highly endemic. Samples from undifferentiated febrile illness (UFI) patients were obtained from a local hospital. A total of 200 UFI patient samples were obtained and 309 rodents and 420 pools of ectoparasites were collected from rodents (
= 285) and domestic animals (
= 135). The bacterial 16S rRNA gene was amplified and sequenced with the Illumina. Real-time PCR and Sanger sequencing were used to confirm the next-generation sequencing (NGS) results and to characterize pathogen species. Several pathogens were detected by NGS in all populations studied and the most common pathogens identified included
spp.,
spp.,
spp., and
. Interestingly,
spp. was detected in patient, rodent and tick populations, although they were not previously known to cause human disease from this region.
Neoehrlichia,
spp.,
spp., and
spp. were detected in rodents and their associated ectoparasites. The same
genotypes were shared among UFI patients, rodents, and chiggers in a single district indicating that the chiggers found on rodents were also likely responsible for transmitting to people. Serological testing using immunofluorescence assays in UFI samples showed high prevalence (IgM/IgG) of
and
pathogens, most notably among samples collected during September-November. Additionally, a higher number of seropositive samples belonged to patients in the working age population (20-60 years old). The results presented in this study demonstrate that the increased risk of human infection or exposure to chiggers and their associated pathogen (
) resulted in part from two important factors; working age group and seasons for rice cultivation and harvesting. Evidence of pathogen exposure was shown to occur as there was seropositivity (IgG) in UFI patients for bartonellosis as well as for anaplasmosis. Using a metagenomic approach, this study demonstrated the circulation and transmission of several pathogens in the environment, some of which are known causative agents of illness in human populations.
Trombiculid mites are the vectors of scrub typhus, with infected larval mites (chiggers) transmitting the causative agent, Orientia tsutsugamushi, during feeding. Co-existence of multiple O. ...tsutsugamushi strains within infected mites has previously been reported in naturally infected, laboratory-reared mite lines using molecular methods to characterize the 56-kDa type-specific antigen (TSA) gene. In the current study, more advanced next-generation sequencing technology was used to reveal the heterogeneity of O. tsutsugamushi genotypes in field-collected trombiculid mites from rodents and small mammals in scrub typhus-endemic areas of Thailand. Twenty-eight trombiculid mites collected from 10 small mammals were positive for O. tsutsugamushi, corresponding to a prevalence rate of 0.7% within the mite population. Twenty-four of the infected mites were Leptotrombidium spp., indicating that this genus is the main vector for O. tsutsugamushi transmission in Thailand. In addition, O. tsutsugamushi was detected in the mite genera Ascoschoengastia, Blankaartia, Gahrliepia, and Lorillatum. Of the 10 infested small animal hosts, six had 2-10 infected mites feeding at the time of collection. Deep sequencing was used to characterize mixed infections (two to three O. tsutsugamushi genotypes within an individual mite), and 5 of the 28 infected mites (17.9%) contained mixed infections. Additionally, 56-kDa TSA gene sequence analysis revealed identical bacterial genotypes among co-feeding mites with single or mixed infections. These results suggest that co-feeding transmission may occur during the feeding process, and could explain the occurrence of mixed infections in individual mites, as well as the recovery of multiple infected mites from the same host. This study also revealed highly diverse within-host O. tsutsugamushi genotypes. The occurrence of multiple O. tsutsugamushi genotypes within individual mites has important implications, and could provide a mechanism for pathogen evolution/diversification in the mite vector.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Borrelia miyamotoi is a relapsing fever spirochete that shares the same vector as Lyme disease causing Borrelia. This epidemiological study of B. miyamotoi was conducted in rodent reservoirs, tick ...vectors and human populations simultaneously. A total of 640 rodents and 43 ticks were collected from Phop Phra district, Tak province, Thailand. The prevalence rate for all Borrelia species was 2.3% and for B. miyamotoi was 1.1% in the rodent population, while the prevalence rate was quite high in ticks collected from rodents with an infection rate of 14.5% (95% CI: 6.3-27.6%). Borrelia miyamotoi was detected in Ixodes granulatus collected from Mus caroli and Berylmys bowersi, and was also detected in several rodent species (Bandicota indica, Mus spp., and Leopoldamys sabanus) that live in a cultivated land, increasing the risk of human exposure. Phylogenetic analysis revealed that the B. miyamotoi isolates detected in rodents and I. granulatus ticks in this study were similar to isolates detected in European countries. Further investigation was conducted to determine the serological reactivity to B. miyamotoi in human samples received from Phop Phra hospital, Tak province and in rodents captured from Phop Phra district using an in-house, direct enzyme-linked immunosorbent assay (ELISA) assay with B. miyamotoi recombinant glycerophosphodiester-phosphodiesterase (rGlpQ) protein as coated antigen. The results showed that 17.9% (15/84) of human patients and 9.0% (41/456) of captured rodents had serological reactivity to B. miyamotoi rGlpQ protein in the study area. While a low level of IgG antibody titers (100-200) was observed in the majority of seroreactive samples, higher titers (400-1,600) were also detected in both humans and rodents. This study provides the first evidence of B. miyamotoi exposure in human and rodent populations in Thailand and the possible roles of local rodent species and Ixodes granulatus tick in its enzootic transmission cycle in nature.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Tick-borne diseases (TBD) are considered neglected diseases in Thailand with disease burden likely underestimated. To assess risk for emerging TBD in Thailand, the seasonality of questing tick and ...pathogen prevalence were studied in Khao Yai National Park, a top tourist destination.
During 2019, questing ticks around tourist attractions were systematically collected bimonthly and analyzed for Rickettsia and Anaplasmataceae bacterial species by polymerase chain reaction and DNA sequencing.
Larvae and nymphs of questing ticks peaked in Khao Yai National Park during the late rainy-winter season, though no specific trends were observed in adult ticks. Winter (November to February) was the highest risk for human tick-bites due to higher numbers of both ticks and visitors. Of the total 5916 ticks analyzed (651 pools), Anaplasma phagocytophilum, Neoehrlichia mikurensis, Ehrlichia ewingii, and Ehrlichia chaffeensis were detected at low rates (≤0.05%). There was a higher prevalence of human rickettsioses (0.2–7%) in ticks surveyed with Rickettsia tamurae, Rickettsia raoultii, and Rickettsia montana the major species. Amblyomma ticks had the highest prevalence of Rickettsia (85%, 35/44 Amblyomma adults), in which only R. tamurae and R. raoultii were found in Amblyomma with mixed species infections common. We report the first detection of R. africae-like and N. mikurensis in Ixodes granulatus adults in Thailand, suggesting I. granulatus as a potential vector for these pathogens.
This study demonstrated the risk of emerging TBD in Thailand and underscores the need for tick-bite prevention among tourists in Thailand.
The main objective of this study was to compare the performance of nested PCR with expert microscopy as a means of detecting Plasmodium parasites during active malaria surveillance in western ...Thailand.
The study was performed from May 2000 to April 2002 in the village of Kong Mong Tha, located in western Thailand. Plasmodium vivax (PV) and Plasmodium falciparum (PF) are the predominant parasite species in this village, followed by Plasmodium malariae (PM) and Plasmodium ovale (PO). Each month, fingerprick blood samples were taken from each participating individual and used to prepare thick and thin blood films and for PCR analysis.
PCR was sensitive (96%) and specific (98%) for malaria at parasite densities > or = 500/microl; however, only 18% (47/269) of P. falciparum- and 5% (20/390) of P. vivax-positive films had parasite densities this high. Performance of PCR decreased markedly at parasite densities <500/microl, with sensitivity of only 20% for P. falciparum and 24% for P. vivax at densities <100 parasites/microl.
Although PCR performance appeared poor when compared to microscopy, data indicated that the discrepancy between the two methods resulted from poor performance of microscopy at low parasite densities rather than poor performance of PCR. These data are not unusual when the diagnostic method being evaluated is more sensitive than the reference method. PCR appears to be a useful method for detecting Plasmodium parasites during active malaria surveillance in Thailand.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Next generation sequencing (NGS) technology has been used for a wide range of epidemiological and surveillance studies. Here, we used amplicon-based NGS to species identify
and their arthropod hosts ...from entomological surveillance.
During 2015-2016, we screened 1825 samples of rodents and ectoparasites collected from rodents and domestic mammals (dog, cat, and cattle) across Thailand for
. The citrate synthase gene was amplified to identify
to species, while the Cytochrome Oxidase subunit I (
I) and subunit II (
II) genes were used as target genes for ectoparasite identification. All target gene amplicons were pooled for library preparation and sequenced with Illumina MiSeq platform.
The highest percentage of
DNA was observed in fleas collected from domestic animals (56%) predominantly dogs. Only a few samples of ticks from domestic animals, rodent fleas, and rodent tissue were positive for
DNA. NGS based characterization of
by host identified
as the most common bacteria in positive fleas collected from dogs (83.2%) while "
Rickettsia senegalensis" was detected in only 16.8% of
positive dog fleas. Sequence analysis of
I and
II revealed that almost all fleas collected from dogs were
. Other
species were detected by NGS including
from two
ticks, and
in two rodent tissue samples.
This study demonstrates the utility of NGS for high-throughput sequencing in the species characterization/identification of bacteria and ectoparasite for entomological surveillance of rickettsiae. A high percentage of
are positive for
. In addition, our findings indicate there is a risk of tick-borne Spotted Fever Group rickettsiosis, and flea-borne murine typhus transmission in Tak and Phangnga provinces of Thailand.
Ticks are known vectors for a variety of pathogens including bacteria, viruses, fungi, and parasites. In this study, bacterial communities were investigated in active life stages of three tick genera ...(
Haemaphysalis, Dermacentor
, and
Amblyomma
) collected from Khao Yai National Park in Thailand. Four hundred and thirty-three questing ticks were selected for pathogen detection individually using real-time PCR assays, and 58 of these were subjected to further metagenomics analysis. A total of 62 ticks were found to be infected with pathogenic bacteria, for a 14.3% prevalence rate, with
Amblyomma
spp. exhibiting the highest infection rate (20.5%), followed by
Haemaphysalis
spp. (14.5%) and
Dermacentor
spp. (8.6%).
Rickettsia
spp. were the most prevalent bacteria (7.9%) found, followed by
Ehrlichia
spp. (3.2%), and
Anaplasma
spp. and
Borrelia
spp. each with a similar prevalence of 1.6%. Co-infection between pathogenic bacteria was only detected in three
Haemaphysalis
females, and all co-infections were between
Rickettsia
spp. and Anaplasmataceae (
Ehrlichia
spp. or
Anaplasma
spp.), accounting for 4.6% of infected ticks or 0.7% of all examined questing ticks. The prevalence of the
Coxiella
-like endosymbiont was also investigated. Of ticks tested, 65.8% were positive for the
Coxiella
-like endosymbiont, with the highest infection rate in nymphs (86.7%), followed by females (83.4%). Among tick genera,
Haemaphysalis
exhibited the highest prevalence of infection with the
Coxiella
-like endosymbiont. Ticks harboring the
Coxiella
-like endosymbiont were more likely to be infected with
Ehrlichia
spp. or
Rickettsia
spp. than those without, with statistical significance for
Ehrlichia
spp. infection in particular (
p
-values = 0.003 and 0.917 for
Ehrlichia
spp. and
Rickettsia
spp., respectively). Profiling the bacterial community in ticks using metagenomics revealed distinct, predominant bacterial taxa in tick genera. Alpha and beta diversities analyses showed that the bacterial community diversity and composition in
Haemaphysalis
spp. was significantly different from
Amblyomma
spp. However, when examining bacterial diversity among tick life stages (larva, nymph, and adult) in
Haemaphysalis
spp., no significant difference among life stages was detected. These results provide valuable information on the bacterial community composition and co-infection rates in questing ticks in Thailand, with implications for animal and human health.
Leptospirosis is a zoonosis known to be endemic in the Mekong Delta of Vietnam, even though clinical reports are uncommon. We investigated leptospira infection in rats purchased in food markets ...during the rainy season (October) (
n
=150), as well as those trapped during the dry season (February–March) (
n
=125) in the region using RT-PCR for the
lipL32
gene, confirmed by 16S rRNA, as well as by the microscopic agglutination test (MAT). Results were compared with the serovar distribution of human cases referred from Ho Chi Minh City hospitals (2004–2012) confirmed by MAT (
n
=45). The MAT seroprevalence among rats was 18.3%. The highest MAT seroprevalence corresponded, in decreasing order, to:
Rattus norvegicus
(33.0%),
Bandicota indica
(26.5%),
Rattus tanezumi
(24.6%),
Rattus exulans
(14.3%), and
Rattus argentiventer
(7.1%). The most prevalent serovars were, in descending order: Javanica (4.6% rats), Louisiana (4.2%), Copenageni (4.2%), Cynopterie (3.7%), Pomona (2.9%), and Icterohaemorrhagiae (2.5%). A total of 16 rats (5.8%) tested positive by RT-PCR. Overall, larger rats tended to have a higher prevalence of detection. There was considerable agreement between MAT and PCR (kappa=0.28 0.07–0.49), although significantly more rats were positive by MAT (McNemar 29.9 (
p
<0.001). MAT prevalence was higher among rats during the rainy season compared with rats in the dry season. There are no current available data on leptospira serovars in humans in the Mekong Delta, although existing studies suggest limited overlapping between human and rat serovars. Further studies should take into account a wider range of potential reservoirs (
i.e
., dogs, pigs) as well as perform geographically linked co-sampling of humans and animals to establish the main sources of leptospirosis in the region.
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