Poonyapat Sedwisai

Detection and phylogenetic characterization of hepatitis E virus genotype 3 in a captive wild boar in Thailand.

Hepatitis E virus (HEV) was studied in different types of wild boar captive settings in Thailand, including a wildlife breeding research station, zoo, and commercial wild boar farm, which were located in different locations of Thailand. Fifty-one fecal samples were collected and screened for HEV RNA and then analyzed. One sample obtained from a wildlife breeding research station in Ratchaburi province was HEV positive. Phylogenetic characterization revealed that the virus was HEV genotype 3 and belongs to subgroup 3e, which is closely related to HEV recently isolated from domestic pigs and humans in the country. It was hypothesized that HEV is shared among wild boars, domestic pigs, and humans in Thailand.

Seasonal abundance and potential of Japanese encephalitis virus infection in mosquitoes at the nesting colony of ardeid birds, Thailand

OBJECTIVE To investigate the abundance and seasonal dynamics of mosquitoes, and to detect Japanese encephalitis virus (JEV) in these mosquitoes at the nesting colony of ardeid birds. METHODS Mosquitoes were collected bimonthly from July 2009 to May 2010 by Centers for Disease Control. Light traps and dry ice, as a source of CO2, were employed to attract mosquitoes. Mosquitoes were first identified, pooled into groups of upto 50 mosquitoes by species, and tested for JEV infection by viral isolation and reverse transcriptase polymerase chain reaction. RESULTS A total of 20 370 mosquitoes comprising 14 species in five genera were collected. The five most abundant mosquito species collected were Culex tritaeniorhynchus (95.46%), Culex vishnui (2.68%), Culex gelidus (0.72%), Anopheles peditaeniatus (0.58%) and Culex quinquefasciatus (0.22%). Mosquito peak densities were observed in July. All of 416 mosquito pools were negative for JEV. CONCLUSIONS This study provides new information about mosquito species and status of JEV infection in mosquitoes in Thailand. Further study should be done to continue a close survey for the presence of this virus in the ardeid birds.

Molecular epidemiology of bovine Babesia spp. and Theileria orientalis parasites in beef cattle from northern and northeastern Thailand.

Beef cattle production represents the largest cattle population in Thailand. Their productivity is constrained by tick-borne diseases such as babesiosis and theileriosis. In this study, we determined the prevalence of Babesia bigemina, Babesia bovis and Theileria orientalis using polymerase chain reaction (PCR). The genetic markers that were used for detection of the above parasites were sequenced to determine identities and similarity for Babesia spp. and genetic diversity of T. orientalis. Furthermore the risk factors for the occurrence of the above protozoan parasites in beef cattle from northern and northeastern parts of Thailand were assessed. A total of 329 blood samples were collected from beef cattle in 6 provinces. The study revealed that T. orientalis was the most prevalent (30.1%) parasite in beef cattle followed by B. bigemina (13.1%) and B. bovis (5.5%). Overall, 78.7% of the cattle screened were infected with at least one of the above parasites. Co-infection with Babesia spp. and T. orientalis was 30.1%. B. bigemina and T. orientalis were the most prevalent (15.1%) co-infection although triple infection with the three parasites was observed in 3.0% of the samples. Sequencing analysis revealed that B. bigemina RAP1 gene and B. bovis SBP2 gene were conserved among the parasites from different cattle samples. Phylogenetic analysis showed that the T. orientalis MPSP gene from parasites isolated from cattle in north and northeast Thailand was classified into types 5 and 7 as reported previously. Lack of tick control program was the universal risk factor of the occurrence of Babesia spp. and T. orientalis infection in beef cattle in northern and northeastern Thailand. We therefore recommend training of farmers on appropriate tick control strategies and further research on potential vectors for T. orientalis and elucidate the effect of co-infection with Babesia spp. on the pathogenicity of T. orientalis infection on beef in northern and northeastern Thailand.

Mosquito distribution and West Nile virus infection in zoos and in important sites of migratory and resident birds, Thailand

Objective To investigate the distribution of mosquito species in the zoos and in important sites of migratory and resident birds and evaluate West Nile virus (WNV) infection in mosquito species.

A traditional cattle trade network in Tak province, Thailand and its potential in the spread of infectious diseases

Cattle in Thailand are traded by cattle dealers in the cattle markets through informal negotiation processes. The present study aimed to explore a traditional cattle trade network and its potential in the spread of infectious diseases. A cross-sectional questionnaire-based survey was conducted in cattle markets located in Tak province, Thailand. A static weighted directed one-mode network was constructed and geographic locations of sources and destinations of animals were plotted. A total of 210 cattle dealers responded to the questionnaires. The cattle trade network contained 112 sources and destinations of animals and 168 trading activities. The highest generalised weighed in- and out-degree centralities and k-core were observed in the same cattle market at 53.4, 106.7 and 4, respectively. Spatially, cattle dealers could transport animals as far as 774.4 km from the original markets and natural barriers such as mountainous areas tended to dictate the trading routes, premises of animals and magnitude of trading activities. Traditional cattle trading patterns described in this study pose some important challenges to veterinary authorities in tailoring effective prevention and control measures for confronting infectious diseases. This study quantitatively analysed the traffic within a network of cattle trade and found a wide range of spatial movements and a high connectivity of markets to sources and destinations of animals, which may accommodate the spread of infectious diseases within the network. This peace time network analysis could help related authorities to better focus on possible infected premises and to immediately respond once an epidemic occurs.

Stomoxyini fly fauna of the Khao Yai National Park, Thailand

Objective To determine species diversity, relative population abundance and diurnal activity of the Stomoxyini flies at the Khao Yai National Park.

Species identification of horse flies (Diptera: Tabanidae) in Thailand using DNA barcoding

Horse flies (Diptera: Tabanidae) are of medical and veterinary importance because they are known to transmit pathogens. Approximately 80 species of horse flies have been reported in Thailand. Monitoring the distribution of horse fly species is important to control the spread of diseases transmitted by them. Currently, the species identification of horse flies is based on their morphology; this requires considerable skills and taxonomic expertise, and it may be difficult to identify morphologically similar species. DNA-based identification methods are increasingly being developed for rapid and accurate identification of various insect species. In this study, we used mitochondrial cytochrome oxidase subunit I (COI) for species identification of horse flies in Thailand. A 658 bp fragment of COI was amplified from 145 adult horse flies belonging to 48 morphologically distinct species and sequenced. Sequence analysis revealed an intraspecific divergence of 0.0%-4.4% and an interspecific divergence of 0.0%-16.2%. Our results showed that COI barcodes were effective in discriminating a majority of horse flies in Thailand on the basis of the barcoding gap and phylogenetic analyses. However, COI barcodes were unable to distinguish among members of the Tabanus striatus complex and some species within the T. ceylonicus group.

A LONG-TERM SEROSURVEY OF AVIAN INFLUENZA H5 AMONG WILD BIRDS IN NAKHON SAWAN PROVINCE, THAILAND

Abstract:  An outbreak of HPAIV H5N1 in Nakhon Sawan province, Thailand, in 2004 caused sporadic deaths of Asian openbill storks (Anastomus oscitans). An investigation was undertaken to determine if this virus occurs and circulates in wild birds in Nakhon Sawan province. Following the outbreak, a widespread serosurvey was conducted using the hemagglutination inhibition assay and microneutralization assay to detect antibodies against AIV H5. From 2007 to 2014, blood was collected from a total of 753 wild birds, representing 10 orders and 44 species. The results reveal that 10 serum samples were positive for AIV H5 antibodies. These seropositive results, found in the orders Ciconiiformes and Anseriformes, demonstrate that waterfowl serve as a reservoir host of AIV. Moreover, the seroprevalences in streak-eared bulbul showed habitat sharing with waterfowl or duck.