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Dukpa K.,National Center for Animal Health | Dukpa K.,Murdoch University | Robertson I.D.,Murdoch University | Ellis T.,Murdoch University
Preventive Veterinary Medicine | Year: 2012

Serological and clinical studies were conducted between March 2009 and August 2010 to validate the foot-and-mouth disease free status of Tsirang district of Bhutan as determined by the country's passive surveillance system. Randomised (first survey) and targeted (third survey) samplings, with subsequent follow-up samplings (second and fourth), were conducted on FMD-susceptible animals to detect the disease at a design prevalence of 25% and 20% at the individual animal-level and village-level, respectively. Sera from cattle, goats, pigs, and sheep were tested for the presence of non-structural protein (NSP) antibodies using two commercial (PrioCHECK ® FMDV NS and CHEKIT ®-FMD-3ABC-bo-ov) and one in-house NSP kit (c-ELISA, AAHL, Australia). The overall seropositivity (all species) at the animal-level was 3% (95% CI: 1.7, 4.8) and 3.5% (95% CI: 2.1, 5.4), for the randomised and targeted surveys, respectively. Except for one goat from the first survey, none of the small ruminants and pigs had NSP antibodies. The seropositives from the first and targeted surveys were distributed among 13 and 16 of 20 villages sampled, respectively. All repeat testing from the initial seropositive animals and their herd mates, for both the first and third surveys, were negative in the NSP tests 6-8 months later. Using the hypergeometric exact probability formula for two-stage analyses, the results enabled rejection of the null hypothesis and supported conclusion that the population was free from disease at the minimum expected prevalence of 20% at the 95.53% and 99.46% confidence levels, for the randomised and targeted surveys, respectively. Clinical surveillance also showed absence of disease or clinical signs suggestive of FMD. The few seropositives were likely to be false positives due to factors such as imperfect specificities of the tests and possible NSP-residues in the vaccines. The study has paved the way for initiation of zoning approaches for the progressive control of FMD in Bhutan. © 2011 Elsevier B.V. Source

Dukpa K.,National Center for Animal Health | Dukpa K.,Murdoch University | Robertson I.D.,Murdoch University | Edwards J.R.,Murdoch University | Ellis T.M.,Murdoch University
Tropical Animal Health and Production | Year: 2011

A retrospective study on the outbreaks of foot-and-mouth disease (FMD) in Bhutan, between the years 1996 and 2008, based on the data collected through passive surveillance, was undertaken. A total of 230 outbreaks of FMD at sub-district level were recorded in 299 villages located in 19 out of the 20 districts in the country. There were no significant differences between the years (P = 0.998) or months (P = 0.989) on the incidence of FMD. The sub-districts in the north (altitude >1,000 m above mean sea level) had significantly (P = 0.008) higher incidences of outbreaks in winter than in summer. The sub-districts that shared border with India had significantly more outbreaks than those that didn't (P = 0.001). Cattle were the most predominant species affected being involved in all of the outbreaks reported. Serotype O, which constituted 70.6% of the outbreaks typed was the most predominant serotype prevalent in Bhutan followed by A (16.7%), Asia 1 (8.8%), and C (3.9%). Cattle density was significantly positively correlated (P = 0.023) with the incidence of disease. Three waves of outbreaks of epidemic proportions were reported in 1997/1998, 2002/2003, and 2007/2008 due to the PanAsia strain of the O serotype. The study highlights the incursion of the PanAsia strain of the O serotype into the country, possibly, through the transboundary movement of animals and the need for active surveillance of FMD, especially at the border areas. The study also highlights the significance of the O serotype and cattle as the main indicator species in the epidemiology of FMD in Bhutan. The findings from this study can be used as baseline epidemiological data for further research to understand the epidemiology of FMD in Bhutan. © 2010 Springer Science+Business Media B.V. Source

Dukpa K.,National Center for Animal Health | Dukpa K.,Murdoch University | Robertson I.D.,Murdoch University | Ellis T.M.,Murdoch University
Preventive Veterinary Medicine | Year: 2011

Cross sectional serological surveys were conducted between March and December 2009 to determine the distribution of foot-and-mouth disease and also to validate the current passive surveillance system in Bhutan. A total of 1909 sera collected from cattle, goats, sheep, and pigs, from 485 herds in 106 villages, were tested using a foot-and-mouth disease non-structural protein 3ABC ELISA. The true prevalence at the animal-level for all species was 15% (95% CI: 13.5, 16.7) using the sensitivity (97.2%) and specificity (99.5%) for cattle. The true prevalence for cattle, goats, sheep and pigs were 17.6 (95% CI: 15.6, 19.5), 11.9% (95% CI: 5.6, 18.3), 11.9% (95% CI: 1.3, 25.1), and 1.9% (95% CI: 0.0, 3.8), respectively.The sub-districts that shared border with India had significantly (p= 0.03) higher seroprevalence than the interior sub-districts. Villages located in the sub-tropical zone had significantly (p< 0.0001) higher seroprevalence than those located at high altitude zones. Herds with known outbreaks of FMD were 3.6 times more likely (p< 0.001) to be seropositive than those with no history of outbreaks of FMD. The study showed the usefulness of population-based serological surveys in detecting circulation of active infection in populations which were, until now, considered to be free of disease based on a passive surveillance system. The study also highlighted the benefits of conducting serological and questionnaire surveys, simultaneously, to ascertain the infection status of herds and animals. Some of the findings from this study could be considered for strengthening of the current FMD control program in Bhutan. © 2011 Elsevier B.V. Source

Coates B.S.,Corn Insects and Crop Genetics Research Unit | Bayles D.O.,National Center for Animal Health | Wanner K.W.,Montana State University | Robertson H.M.,University of Illinois at Urbana - Champaign | And 4 more authors.
Frontiers in Genetics | Year: 2011

Microsatellite markers are difficult to apply within lepidopteran studies due to the lack of locus-specific PCR amplification and the high proportion of "null" alleles, such that erroneous estimations of population genetic parameters often result. Herein single nucleotide polymorphism (SNP) markers are developed from Ostrinia nubilalis (Lepidoptera: Cram-bidae) using next generation expressed sequence tag (EST) data. A total of 2742 SNPs were predicted within a reference assembly of 7414 EST contigs, and a subset of 763 were incorporated into 24 multiplex PCR reactions. To validate this pipeline, 5 European and North American sample sites were genotyped at 178 SNP loci, which indicated 84 (47.2%) were in Hardy-Weinberg equilibrium. Locus-by-locus FST, analysis of molecular variance, and STRUCTURE analyses indicate significant genetic differentiation may exist between European and North American O. nubilalis. The observed genetic diversity was significantly lower among European sites, which may result from genetic drift, natural selection, a genetic bottleneck, or ascertainment bias due to North American origin of EST sequence data. SNPs are an abundant source of mutation data for molecular genetic marker development in non-model species, with shared ancestral SNPs showing application within closely related species. These markers offer advantages over microsatellite markers for genetic and genomic analyses of Lepidoptera, but the source of mutation data may affect the estimation of population parameters and likely need to be considered in the interpretation of empirical data. © 2011 Coates, Bayles, Wanner, Robertson, Hellmich and Sappington. Source

Hidano A.,Massey University | Dukpa K.,National Center for Animal Health | Rinzin K.,National Center for Animal Health | Rinzin K.,Murdoch University | And 3 more authors.
Preventive Veterinary Medicine | Year: 2016

We describe the population demographics, rudimentary measures of reproductive performance, the prevalence of major disease conditions and reason-specific proportional mortality for cattle owned by villagers in 16 dzongkhags (districts) in Bhutan based on the findings of a cross-sectional study carried out between March 2012 and May 2014. The animal health issues that were of concern for livestock owners are also identified. Study households were selected using a stratified, two-stage cluster design. Districts (dzongkhags) formed the strata. Villages within dzongkhags were the first sampling stage and households within villages the second sampling stage. All cattle within each selected household comprised the study population.Questionnaires were collected from 409 households with 1480 standing cattle. A total of 71.0% (95% CI 67.9%-74.1%) of the standing cattle population were female and the median age of cattle was 5 years (Q25 3 years; Q75 7 years). Exotic breeds of cattle (Jerseys, Brown Swiss, and their crosses) comprised 41.4% of the cattle population with local breeds making up the remainder. Although exotic breeds of cattle had a significantly lower age at first calving (median 4 years) compared to local breeds (median 4.8 years) there was no significant difference in the number of calving events per cow for the two breed groups. Diarrhoea was the most prevalent disease condition with 2.8 (95% CI 1.5-4.6) cases per 100 animals followed by bovine enzootic haematuria with 1.9 (95% CI 1.0-3.3) cases per 100 animals. The most frequently cited cause of death was misadventure (proportional mortality 26.2%, 95% CI 15.7%-39.2%) followed by old age (17.8%, 95% CI 9.5%-29.4%). A lack of access to adequate fodder and pasture was the animal health issue that was cited by interviewees most frequently.We provide no evidence that exotic breeds of cattle have superior reproductive performance compared with local breeds. The major cattle health concern cited by interviewees, lack of access to fodder, is likely to contribute to suboptimal productivity and the relatively high incidence of bovine enzootic haematuria in this population. We propose that a prospective cohort study of Bhutanese cattle is warranted to more fully elucidate factors affecting the productivity and longevity of cattle in Bhutan. © 2016 Elsevier B.V. Source

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