The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Bryce M Buddle - One of the best experts on this subject based on the ideXlab platform.
-
brushtail Possum trichosurus vulpecula social interactions and their implications for bovine tuberculosis epidemiology
Behaviour, 2018Co-Authors: Bryce M Buddle, Kyle S Richardson, Carlos Rouco, Christopher Parry Jewell, N P French, Daniel M TompkinsAbstract:The brushtail Possum is the main reservoir of bovine tuberculosis in New Zealand. Disease prevalence is generally higher in males than in females. This has conventionally been assumed due to greater infection rates of males, but recent work has raised the hypothesis that it may instead be driven by survival differences. With bovine tuberculosis transmission among Possums most likely occurring between individuals in close proximity, here we analyse social networks built on data from wild Possums collared with contact loggers inhabiting a native New Zealand forest, to investigate whether there is mechanistic support for higher male infection rates. Our results revealed that adult female Possums were generally just as connected with adult male Possums as other adult males are, with male–female connection patterns not being significantly different. This result suggest that the new ‘survivorship’ hypothesis for the sex bias is more likely than the conventional ‘infection rate’ hypothesis.
-
investigating brushtail Possum trichosurus vulpecula home range size determinants in a new zealand native forest
Wildlife Research, 2017Co-Authors: Bryce M Buddle, Kyle S Richardson, Carlos Rouco, Christopher Parry Jewell, N P French, Daniel M TompkinsAbstract:Context. The Australian brushtail Possums (Trichosurus vulpecula) introduction to New Zealand has exacted a heavy toll on native biodiversity and presented the country with its greatest wildlife reservoir host for bovine tuberculosis (TB). Management efforts to control both Possums and TB have been ongoing for decades, and the biology of Possums has been studied extensively in Australia and New Zealand over the past 50 years; however, we still do not have a clear understanding of its home-range dynamics.Aims. To investigate determinants of home range size by using a uniquely large dataset in the Orongorongo Valley, a highly monitored research area in New Zealand and compare our findings with those of other studies.Methods. Possum density was estimated, for subpopulations on four 13-ha cage-trap grids, by the spatially explicit capture–mark–recapture analysis of trapping data from 10 consecutive months. Home ranges were estimated from trap locations using a 100% minimum convex polygon (MCP) method for 348 individuals and analysed with respect to grid, age and sex.Key results. Mean (standard error) Possum density, estimated as 4.87 (0.19), 6.92 (0.29), 4.08 (0.21) and 4.20 (0.19) ha–1 for the four grids, was significantly negatively correlated with mean MCP home-range size. Grid, age, and the interaction of age and sex were significantly related to home-range size. Older Possums had larger home ranges than did younger Possums. When ‘juvenile cohort’ and ‘adult cohort’ data were analysed separately, to investigate the significant interaction, males in the ‘adult cohort’ had significantly larger home ranges than did females, with the grid effect still being apparent, whereas neither sex nor grid effects were significant for the ‘juvenile cohort’.Conclusions. Our findings indicate that, in addition to density, age and sex are likely to be consistent determinants of Possum home-range size, but their influences may be masked in some studies by the complexity of wild-population dynamics.Implications. Our findings have strong implications regarding both disease transmission among Possums and Possum management. The fact that adult males occupy larger home ranges and the understanding that Possum home range increases as population density decreases are an indication that males may be the primary drivers of disease transmission in Possum populations. The understanding that Possum home range increases as population density decreases could be a direct reflection of the ability of TB to persist in the wild that counteracts current management procedures. If individuals, and particularly males, infected with TB can withstand control measures, their ensuing home-range expansion will result in possible bacteria spread in both the expanded area of habitation and new individuals becoming subjected to infection (both immigrant Possums and other control survivors). Therefore, managers should consider potential approaches for luring Possum males in control operations.
-
field trial of an aerially distributed tuberculosis vaccine in a low density wildlife population of brushtail Possums trichosurus vulpecula
PLOS ONE, 2016Co-Authors: Graham Nugent, Ivor Yockney, Martin L. Cross, Jackie E. Whitford, Frank E. Aldwell, Bryce M BuddleAbstract:Oral-delivery Mycobacterium bovis bacillus Calmette-Guerin (BCG) vaccine in a lipid matrix has been shown to confer protection against M. bovis infection and reduce the severity of tuberculosis (TB) when fed to brushtail Possums (Trichosurus vulpecula), the major wildlife vector of bovine TB in New Zealand. Here we demonstrate the feasibility of aerial delivery of this live vaccine in bait form to an M. bovis-infected wild Possum population, and subsequently assess vaccine uptake and field efficacy. Pre-trial studies indicated a resident Possum population at very low density ( 5 baits available per Possum. Blood sampling conducted two months later provided some evidence of vaccine uptake. A necropsy survey conducted one year later identified a lower prevalence of culture-confirmed M. bovis infection and/or gross TB lesions among adult Possums in vaccinated areas (1.1% prevalence; 95% CI, 0-3.3%, n = 92) than in unvaccinated areas (5.6%; 0.7-10.5%, n = 89); P = 0.098. Although not statistically different, the 81% efficacy in protecting Possums against natural infection calculated from these data is within the range of previous estimates of vaccine efficacy in trials where BCG vaccine was delivered manually. We conclude that, with further straightforward refinement to improve free-choice uptake, aerial delivery of oral BCG vaccine is likely to be effective in controlling TB in wild Possums. We briefly discuss contexts in which this could potentially become an important complementary tool in achieving national eradication of TB from New Zealand wildlife.
-
Field Trial of an Aerially-Distributed Tuberculosis Vaccine in a Low-Density Wildlife Population of Brushtail Possums (Trichosurus vulpecula)
2016Co-Authors: Graham Nugent, Ivor Yockney, Martin L. Cross, Jackie E. Whitford, Frank E. Aldwell, Bryce M BuddleAbstract:Oral-delivery Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine in a lipid matrix has been shown to confer protection against M. bovis infection and reduce the severity of tuberculosis (TB) when fed to brushtail Possums (Trichosurus vulpecula), the major wildlife vector of bovine TB in New Zealand. Here we demonstrate the feasibility of aerial delivery of this live vaccine in bait form to an M. bovis-infected wild Possum population, and subsequently assess vaccine uptake and field efficacy. Pre-trial studies indicated a resident Possum population at very low density (5 baits available per Possum. Blood sampling conducted two months later provided some evidence of vaccine uptake. A necropsy survey conducted one year later identified a lower prevalence of culture-confirmed M. bovis infection and/or gross TB lesions among adult Possums in vaccinated areas (1.1% prevalence; 95% CI, 0–3.3%, n = 92) than in unvaccinated areas (5.6%; 0.7–10.5%, n = 89); P = 0.098. Although not statistically different, the 81% efficacy in protecting Possums against natural infection calculated from these data is within the range of previous estimates of vaccine efficacy in trials where BCG vaccine was delivered manually. We conclude that, with further straightforward refinement to improve free-choice uptake, aerial delivery of oral BCG vaccine is likely to be effective in controlling TB in wild Possums. We briefly discuss contexts in which this could potentially become an important complementary tool in achieving national eradication of TB from New Zealand wildlife.
-
epidemiology and control of mycobacterium bovis infection in brushtail Possums trichosurus vulpecula the primary wildlife host of bovine tuberculosis in new zealand
New Zealand Veterinary Journal, 2015Co-Authors: Graham Nugent, Bryce M Buddle, G KnowlesAbstract:The introduced Australian brushtail Possum (Trichosurus vulpecula) is a maintenance host for bovine tuberculosis (TB) in New Zealand and plays a central role in the TB problem in this country. The TB-Possum problem emerged in the late 1960s, and intensive lethal control of Possums is now used to reduce densities to low levels over 8 million ha of the country. This review summarises what is currently known about the pathogenesis and epidemiology of TB in Possums, and how the disease responds to Possum control. TB in Possums is a highly lethal disease, with most Possums likely to die within 6 months of becoming infected. The mechanisms of transmission between Possums remain unclear, but appear to require some form of close contact or proximity. At large geographic scales, TB prevalence in Possum populations is usually low (1–5%), but local prevalence can sometimes reach 60%. Intensive, systematic and uniform population control has been highly effective in breaking the TB cycle in Possum populations, and where that control has been sustained for many years the prevalence of TB is now zero or near zero. Although some uncertainties remain, local eradication of TB from Possums appears to be straightforward, given that TB managers now have the ability to reduce Possum numbers to near zero levels and to maintain them at those levels for extended periods where required. We conclude that, although far from complete, the current understanding of TB-Possum epidemiology, and the current management strategies and tactics, are sufficient to achieve local, regional, and even national disease eradication from Possums in New Zealand.
R S Morris - One of the best experts on this subject based on the ideXlab platform.
-
the re emergence of mycobacterium bovis infection in brushtail Possums trichosurus vulpecula after localised Possum eradication
New Zealand Veterinary Journal, 2003Co-Authors: L A Corner, Mark Stevenson, D M Collins, R S MorrisAbstract:Abstract AIM: To examine the spatial and temporal pattern of Mycobacterium bovis (bovine tuberculosis) infection in a population of brushtail Possums (Trichosurus vulpecula) after localised Possum eradication. METHODS: Possums on a 36 ha site were eradicated and re-population from the surrounding area studied using population surveys conducted approximately every 2 months for 40 months from the cessation of eradication activity (month zero), using a capture-release programme. At each trapping session, all Possums were examined for clinical signs of tuberculosis. The diagnosis of tuberculosis was confirmed by the isolation of Mycobacterium bovis, and restriction endonuclease analysis (REA) was used to type the isolates. Infected Possums were categorised as residents (present on the site for at least 6 months before diagnosis), range expanders (adult Possums which had extended their nearby home ranges to become trappable within the study site), or juvenile immigrants (sub-adult Possums which had dispersed i...
-
the efficacy of bacille calmette guerin vaccine in wild brushtail Possums trichosurus vulpecula
Research in Veterinary Science, 2002Co-Authors: L A Corner, Bryce M Buddle, S Norton, R S MorrisAbstract:A population of wild brushtail Possums (Trichosurus vulpecula) in which bovine tuberculosis was endemic was vaccinated with live bacille Calmette-Guerin (BCG) to determine the efficacy of vaccination. The population on the 56 hectare site was monitored bimonthly over 2 years using a capture-release regime. During the study tuberculosis was diagnosed by clinical and post mortem examination. Possums were vaccinated with BCG by both intranasal aerosol and conjunctival instillation. Possums were revaccinated on average every 5 months. Over the 2 years, 300 Possums were recruited to the study with 149 being allocated to the vaccination group. There were significantly fewer cases of tuberculosis in the vaccinated (4 cases) than in the unvaccinated group (13 cases; P=0.023). The vaccine efficacy was 69%. An attempt was made to increase the incidence of disease by releasing onto the site Possums that had been experimentally infected with a strain of M. bovis unknown in the area. However, this did not result in any additional cases. BCG vaccine was shown to have a level of efficacy which could be of assistance in controlling tuberculosis in wild Possum populations. The future use of vaccination for the control of tuberculosis in wild Possum populations is discussed.
-
vaccination of the brushtail Possum trichosurus vulpecula against mycobacterium bovis infection with bacille calmette guerin the response to multiple doses
Veterinary Microbiology, 2002Co-Authors: L A Corner, Bryce M Buddle, D U Pfeiffer, R S MorrisAbstract:In New Zealand, the brushtail Possum (Trichosurus vulpecula) is the principal wildlife vector of bovine tuberculosis. Control of infected Possum populations contributes to the control of tuberculosis in domestic livestock. Vaccination is potentially a complementary strategy to population control, but to be cost-effective, administration of the vaccine to Possums would need to be from an appropriately designed automatic vaccinator. Possums themselves would activate the vaccinator so that it would deliver an aerosol spray of vaccine. There would be no direct way to prevent Possums receiving multiple doses of vaccine. This study examined the effect on protective immunity of repeated vaccination. Captive Possums were vaccinated with BCG strain pasteur 1173P2 either 12 times at weekly intervals, twice at 6-weekly intervals, or once. Vaccination was by a combination of intranasal aerosol and conjunctival instillation. Eight weeks after the last dose of vaccine, all Possums were challenged intratracheally with Mycobacterium bovis strain 83/6235. Vaccination induced a significant immune response as measured by the lymphocyte proliferation assay (LPA). A significant level of protection, as measured by the response to challenge, developed in all the vaccinated Possum groups, but protection was greatest in the group vaccinated 12 times. It was concluded that protection would be enhanced if vaccinations were repeated at short intervals (weekly), but no benefit or detriment resulted from revaccination after longer intervals (1-2 months).
-
aerosol vaccination of the brushtail Possum trichosurus vulpecula with bacille calmette guerin the duration of protection
Veterinary Microbiology, 2001Co-Authors: L A Corner, Bryce M Buddle, D U Pfeiffer, R S MorrisAbstract:Abstract Bovine tuberculosis is endemic in wild brushtail Possums ( Trichosurus vulpecula ) in New Zealand. The disease is controlled by reducing or eliminating infected Possum populations, but control methods do not kill all Possums in the targeted area, leaving some tuberculous Possums to maintain the disease. Vaccination with bacille Calmette–Guerin (BCG) has been shown to provide significant levels of protection. Vaccination is a potential alternative or complementary control strategy if protection is long lasting. Captive Possums were vaccinated with a single dose of BCG by intranasal aerosol and challenged by intratracheal instillation of Mycobacterium bovis 2, 6 or 12 months after vaccination. Vaccination produced significant immunity as measured by the lymphocyte proliferative response to bovine PPD and protection in response to challenge. The protective response was seen as a decrease in the mass of pulmonary lesions and decreased dissemination to the abdominal organs and body lymph nodes. The protective effect was strongest at 2 months after vaccination but was still present at a lower level at 12 months. Delivery of an aerosol vaccine to Possums in the wild using a self-delivery system could contribute substantially to wildlife tuberculosis control.
-
behavioural studies on the potential for direct transmission of tuberculosis from feral ferrets mustela furo and Possums trichosurus vulpecula to farmed livestock
New Zealand Veterinary Journal, 1995Co-Authors: C M Sauter, R S MorrisAbstract:Abstract Studies were conducted to evaluate the response of cattle and deer to ferrets which were sedated so they behaved like terminally tuberculous animals, and to compare this with the response of cattle, deer and sheep to sedated Possums. Six groups of deer and two groups of cattle were exposed to a sedated ferret and to a sedated Possum. Both livestock species showed interest in the Possum by sniffing and licking it, but they only briefly touched the ferret and no licking or extended investigation was observed. The proportion of available time spent in physical contact with the Possum by cattle was 7.7 times as high as for the ferret, and for the deer was 5.7 times as high. The behavioural response of three groups of sheep to a sedated Possum was investigated, and sheep showed limited interest beyond viewing the Possum from a distance. The amount of time spent by sheep investigating the Possum was very low and the intensity of exploration was also low. For Possums, at least one deer was within 1.5 m ...
Graham Nugent - One of the best experts on this subject based on the ideXlab platform.
-
field trial of an aerially distributed tuberculosis vaccine in a low density wildlife population of brushtail Possums trichosurus vulpecula
PLOS ONE, 2016Co-Authors: Graham Nugent, Ivor Yockney, Martin L. Cross, Jackie E. Whitford, Frank E. Aldwell, Bryce M BuddleAbstract:Oral-delivery Mycobacterium bovis bacillus Calmette-Guerin (BCG) vaccine in a lipid matrix has been shown to confer protection against M. bovis infection and reduce the severity of tuberculosis (TB) when fed to brushtail Possums (Trichosurus vulpecula), the major wildlife vector of bovine TB in New Zealand. Here we demonstrate the feasibility of aerial delivery of this live vaccine in bait form to an M. bovis-infected wild Possum population, and subsequently assess vaccine uptake and field efficacy. Pre-trial studies indicated a resident Possum population at very low density ( 5 baits available per Possum. Blood sampling conducted two months later provided some evidence of vaccine uptake. A necropsy survey conducted one year later identified a lower prevalence of culture-confirmed M. bovis infection and/or gross TB lesions among adult Possums in vaccinated areas (1.1% prevalence; 95% CI, 0-3.3%, n = 92) than in unvaccinated areas (5.6%; 0.7-10.5%, n = 89); P = 0.098. Although not statistically different, the 81% efficacy in protecting Possums against natural infection calculated from these data is within the range of previous estimates of vaccine efficacy in trials where BCG vaccine was delivered manually. We conclude that, with further straightforward refinement to improve free-choice uptake, aerial delivery of oral BCG vaccine is likely to be effective in controlling TB in wild Possums. We briefly discuss contexts in which this could potentially become an important complementary tool in achieving national eradication of TB from New Zealand wildlife.
-
Field Trial of an Aerially-Distributed Tuberculosis Vaccine in a Low-Density Wildlife Population of Brushtail Possums (Trichosurus vulpecula)
2016Co-Authors: Graham Nugent, Ivor Yockney, Martin L. Cross, Jackie E. Whitford, Frank E. Aldwell, Bryce M BuddleAbstract:Oral-delivery Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine in a lipid matrix has been shown to confer protection against M. bovis infection and reduce the severity of tuberculosis (TB) when fed to brushtail Possums (Trichosurus vulpecula), the major wildlife vector of bovine TB in New Zealand. Here we demonstrate the feasibility of aerial delivery of this live vaccine in bait form to an M. bovis-infected wild Possum population, and subsequently assess vaccine uptake and field efficacy. Pre-trial studies indicated a resident Possum population at very low density (5 baits available per Possum. Blood sampling conducted two months later provided some evidence of vaccine uptake. A necropsy survey conducted one year later identified a lower prevalence of culture-confirmed M. bovis infection and/or gross TB lesions among adult Possums in vaccinated areas (1.1% prevalence; 95% CI, 0–3.3%, n = 92) than in unvaccinated areas (5.6%; 0.7–10.5%, n = 89); P = 0.098. Although not statistically different, the 81% efficacy in protecting Possums against natural infection calculated from these data is within the range of previous estimates of vaccine efficacy in trials where BCG vaccine was delivered manually. We conclude that, with further straightforward refinement to improve free-choice uptake, aerial delivery of oral BCG vaccine is likely to be effective in controlling TB in wild Possums. We briefly discuss contexts in which this could potentially become an important complementary tool in achieving national eradication of TB from New Zealand wildlife.
-
epidemiology and control of mycobacterium bovis infection in brushtail Possums trichosurus vulpecula the primary wildlife host of bovine tuberculosis in new zealand
New Zealand Veterinary Journal, 2015Co-Authors: Graham Nugent, Bryce M Buddle, G KnowlesAbstract:The introduced Australian brushtail Possum (Trichosurus vulpecula) is a maintenance host for bovine tuberculosis (TB) in New Zealand and plays a central role in the TB problem in this country. The TB-Possum problem emerged in the late 1960s, and intensive lethal control of Possums is now used to reduce densities to low levels over 8 million ha of the country. This review summarises what is currently known about the pathogenesis and epidemiology of TB in Possums, and how the disease responds to Possum control. TB in Possums is a highly lethal disease, with most Possums likely to die within 6 months of becoming infected. The mechanisms of transmission between Possums remain unclear, but appear to require some form of close contact or proximity. At large geographic scales, TB prevalence in Possum populations is usually low (1–5%), but local prevalence can sometimes reach 60%. Intensive, systematic and uniform population control has been highly effective in breaking the TB cycle in Possum populations, and where that control has been sustained for many years the prevalence of TB is now zero or near zero. Although some uncertainties remain, local eradication of TB from Possums appears to be straightforward, given that TB managers now have the ability to reduce Possum numbers to near zero levels and to maintain them at those levels for extended periods where required. We conclude that, although far from complete, the current understanding of TB-Possum epidemiology, and the current management strategies and tactics, are sufficient to achieve local, regional, and even national disease eradication from Possums in New Zealand.
-
the epidemiology of mycobacterium bovis in wild deer and feral pigs and their roles in the establishment and spread of bovine tuberculosis in new zealand wildlife
New Zealand Veterinary Journal, 2015Co-Authors: Graham Nugent, Christian Gortazar, G KnowlesAbstract:AbstractIn New Zealand, wild deer and feral pigs are assumed to be spillover hosts for Mycobacterium bovis, and so are not targeted in efforts aimed at locally eradicating bovine tuberculosis (TB) from Possums (Trichosurus vulpecula), the main wildlife host. Here we review the epidemiology of TB in deer and pigs, and assess whether New Zealand's TB management programme could be undermined if these species sometimes achieve maintenance host status.In New Zealand, TB prevalences of up to 47% have been recorded in wild deer sympatric with tuberculous Possums. Patterns of lesion distribution, age-specific prevalences and behavioural observations suggest that deer become infected mainly through exposure to dead or moribund Possums. TB can progress rapidly in some deer (<10%), but generalised disease is uncommon in wild deer; conversely some infected animals can survive for many years. Deer-to-deer transmission of M. bovis is rare, but transmission from tuberculous deer carcasses to scavengers, including Possum...
-
spatial prediction of brushtail Possum trichosurus vulpecula distribution using a combination of remotely sensed and field observed environmental data
Wildlife Research, 2013Co-Authors: Graham Nugent, Thibaud Porphyre, Joanna Mckenzie, Andrea E Byrom, James D Shepherd, Ivor YockneyAbstract:Context In New Zealand, the introduced brushtail Possum, Trichosurus vulpecula, is a reservoir of bovine tuberculosis and as such poses a major threat to the livestock industry. Aerial 1080 poisoning is an important tool for Possum control but is expensive, creating an ongoing need for ever more cost-effective ways of using this technique. Aims To develop geographic information system (GIS) models to better predict spatial variation in the distribution of unmanaged Possum populations, to facilitate better targeting of control activities. Methods Relative abundance of Possums and their distribution among habitat types were surveyed in a dry high-country area of the northern South Island. Two GIS-based models were developed to predict the relative abundance of Possums on trap lines. The first model used remotely sensed (digital) environmental data; the second complemented the remotely sensed data with fine-scale habitat and topographic data collected on the ground. Key results Digital environmental factors and habitat features proved to be key predictors of relative Possum abundance. In both GIS models, height above valley floor, presence of forest cover and mean annual temperature were the strongest predictors. Conclusions Predictive maps (projections) of relative Possum abundance produced from these models can provide useful decision-support tools for pest-control managers, by enabling Possum control to be targeted spatially. Implications Spatially targeted pest control could allow effective control activities for invasive species or disease vectors to be applied at a lower cost for the same benefit.
L A Corner - One of the best experts on this subject based on the ideXlab platform.
-
the re emergence of mycobacterium bovis infection in brushtail Possums trichosurus vulpecula after localised Possum eradication
New Zealand Veterinary Journal, 2003Co-Authors: L A Corner, Mark Stevenson, D M Collins, R S MorrisAbstract:Abstract AIM: To examine the spatial and temporal pattern of Mycobacterium bovis (bovine tuberculosis) infection in a population of brushtail Possums (Trichosurus vulpecula) after localised Possum eradication. METHODS: Possums on a 36 ha site were eradicated and re-population from the surrounding area studied using population surveys conducted approximately every 2 months for 40 months from the cessation of eradication activity (month zero), using a capture-release programme. At each trapping session, all Possums were examined for clinical signs of tuberculosis. The diagnosis of tuberculosis was confirmed by the isolation of Mycobacterium bovis, and restriction endonuclease analysis (REA) was used to type the isolates. Infected Possums were categorised as residents (present on the site for at least 6 months before diagnosis), range expanders (adult Possums which had extended their nearby home ranges to become trappable within the study site), or juvenile immigrants (sub-adult Possums which had dispersed i...
-
the efficacy of bacille calmette guerin vaccine in wild brushtail Possums trichosurus vulpecula
Research in Veterinary Science, 2002Co-Authors: L A Corner, Bryce M Buddle, S Norton, R S MorrisAbstract:A population of wild brushtail Possums (Trichosurus vulpecula) in which bovine tuberculosis was endemic was vaccinated with live bacille Calmette-Guerin (BCG) to determine the efficacy of vaccination. The population on the 56 hectare site was monitored bimonthly over 2 years using a capture-release regime. During the study tuberculosis was diagnosed by clinical and post mortem examination. Possums were vaccinated with BCG by both intranasal aerosol and conjunctival instillation. Possums were revaccinated on average every 5 months. Over the 2 years, 300 Possums were recruited to the study with 149 being allocated to the vaccination group. There were significantly fewer cases of tuberculosis in the vaccinated (4 cases) than in the unvaccinated group (13 cases; P=0.023). The vaccine efficacy was 69%. An attempt was made to increase the incidence of disease by releasing onto the site Possums that had been experimentally infected with a strain of M. bovis unknown in the area. However, this did not result in any additional cases. BCG vaccine was shown to have a level of efficacy which could be of assistance in controlling tuberculosis in wild Possum populations. The future use of vaccination for the control of tuberculosis in wild Possum populations is discussed.
-
vaccination of the brushtail Possum trichosurus vulpecula against mycobacterium bovis infection with bacille calmette guerin the response to multiple doses
Veterinary Microbiology, 2002Co-Authors: L A Corner, Bryce M Buddle, D U Pfeiffer, R S MorrisAbstract:In New Zealand, the brushtail Possum (Trichosurus vulpecula) is the principal wildlife vector of bovine tuberculosis. Control of infected Possum populations contributes to the control of tuberculosis in domestic livestock. Vaccination is potentially a complementary strategy to population control, but to be cost-effective, administration of the vaccine to Possums would need to be from an appropriately designed automatic vaccinator. Possums themselves would activate the vaccinator so that it would deliver an aerosol spray of vaccine. There would be no direct way to prevent Possums receiving multiple doses of vaccine. This study examined the effect on protective immunity of repeated vaccination. Captive Possums were vaccinated with BCG strain pasteur 1173P2 either 12 times at weekly intervals, twice at 6-weekly intervals, or once. Vaccination was by a combination of intranasal aerosol and conjunctival instillation. Eight weeks after the last dose of vaccine, all Possums were challenged intratracheally with Mycobacterium bovis strain 83/6235. Vaccination induced a significant immune response as measured by the lymphocyte proliferation assay (LPA). A significant level of protection, as measured by the response to challenge, developed in all the vaccinated Possum groups, but protection was greatest in the group vaccinated 12 times. It was concluded that protection would be enhanced if vaccinations were repeated at short intervals (weekly), but no benefit or detriment resulted from revaccination after longer intervals (1-2 months).
-
aerosol vaccination of the brushtail Possum trichosurus vulpecula with bacille calmette guerin the duration of protection
Veterinary Microbiology, 2001Co-Authors: L A Corner, Bryce M Buddle, D U Pfeiffer, R S MorrisAbstract:Abstract Bovine tuberculosis is endemic in wild brushtail Possums ( Trichosurus vulpecula ) in New Zealand. The disease is controlled by reducing or eliminating infected Possum populations, but control methods do not kill all Possums in the targeted area, leaving some tuberculous Possums to maintain the disease. Vaccination with bacille Calmette–Guerin (BCG) has been shown to provide significant levels of protection. Vaccination is a potential alternative or complementary control strategy if protection is long lasting. Captive Possums were vaccinated with a single dose of BCG by intranasal aerosol and challenged by intratracheal instillation of Mycobacterium bovis 2, 6 or 12 months after vaccination. Vaccination produced significant immunity as measured by the lymphocyte proliferative response to bovine PPD and protection in response to challenge. The protective response was seen as a decrease in the mass of pulmonary lesions and decreased dissemination to the abdominal organs and body lymph nodes. The protective effect was strongest at 2 months after vaccination but was still present at a lower level at 12 months. Delivery of an aerosol vaccine to Possums in the wild using a self-delivery system could contribute substantially to wildlife tuberculosis control.
Noel W. Davies - One of the best experts on this subject based on the ideXlab platform.
-
Scent Chemicals of the Brushtail Possum, Trichosurus vulpecula
Journal of Chemical Ecology, 2012Co-Authors: Noel W. Davies, Natasha L. WigginsAbstract:The common brushtail Possum ( Trichosurus vulpecula ) is the most widespread browsing marsupial in Australia, where it occupies woodland, agricultural, and urban environments. Following its introduction into New Zealand in the 19th century it has become a major feral pest, threatening native forests. The adaptability of the Possum is thought to be due in part to its social organization, in which chemical communication is important. Possums have cloacal glands and exhibit related marking behavior. This study sought to characterize the chemicals involved in scent marking. Swabs were taken of the cloacal region of 15 Possums (5 females, 10 males) from north-eastern Tasmania and analyzed by gas chromatography–mass spectrometry. There was a large number of compounds present, including 81 branched and unbranched, and saturated and unsaturated, fatty acids (C_4–C_15) and alcohols (C_6–C_26); 27 esters of 2,6- and 2,7-dimethyloctanol; 29 esters of formic acid; 39 sulfur compounds including S_8 and a series of dialkyl disulfides, trisulfides, and tetrasulfides (C_4–C_10); and several alkylglycerol ethers. Many of these cloacal compounds are new to biology. There was considerable individual variability in the relative amounts of compounds found, and no evident sex differences, although the study was not designed to test this. This pattern suggests that these compounds may be acting collectively as a signature mixture of semiochemicals, carrying information on the individual, its kinship, and physiological and social status. This is the first detailed description of putative semiochemicals in any marsupial species.
-
Pharmacokinetics of 1,8-cineole, a dietary toxin, in the brushtail Possum (Trichosurus vulpecula): significance for feeding.
Xenobiotica, 2007Co-Authors: Stuart Mclean, Rebecca Boyle, Sue Brandon, Noel W. Davies, J. S. SorensenAbstract:Cineole (cineole) is a Eucalyptus leaf toxin that defends against predation by herbivores such as the brushtail Possum (Trichosurus vulpecula). The aim of the current study was to characterize the pharmacokinetics of cineole in the Possum to improve understanding about how Possums can avoid cineole toxicity when eating a Eucalyptus diet. Nine male Possums were trapped in the wild and acclimated to captivity; a subcutaneous port was then implanted for venous blood sampling. Cineole was administered intravenously (10 and 15 mg kg -1 ) via a lateral tail vein and orally (30, 100 and 300 mg kg -1 ) by gavage, and blood concentrations of cineole and its metabolites were determined by gas chromatography. Cineole had a large terminal volume of distribution (Vz ¼ 27 l kg -1 ) and a high clearance (43 ml min -1 kg -1 ), equal to hepatic blood flow. The terminal half-life was approximately 7 h. Oral bioavailability was low (F ¼ 0.05) after low doses, but increased tenfold with dose, probably due to saturable first-pass metabolism. These findings indicate that when Possums feed on a cineole diet, they eat until the cineole consumed is sufficient to saturate pre-systemic metabolism, leading to a rapid rise in bioavailability and cineole blood levels, and a cessation of the feeding bout. This is the first report on the pharmacokinetics of a dietary toxin in a wild herbivore, and provides insights into the interactions between the blood concentration of a plant secondary metabolite and the browsing behaviour of a herbivore.
-
application of solid phase microextraction to the quantitative analysis of 1 8 cineole in blood and expired air in a eucalyptus herbivore the brushtail Possum trichosurus vulpecula
Journal of Chromatography B, 2002Co-Authors: Rebecca Boyle, Stuart Mclean, Sue Brandon, G J Pass, Noel W. DaviesAbstract:We have developed two solid-phase microextraction (SPME) methods, coupled with gas chromatography, for quantitatively analysing the major Eucalyptus leaf terpene, 1,8-cineole, in both expired air and blood from the common brushtail Possum (Trichosurus vulpecula). In-line SPME sampling (5 min at 20 °C room temperature) of excurrent air from an expiratory chamber containing a Possum dosed orally with 1,8-cineole (50 mg/kg) allowed real-time semi-quantitative measurements reflecting 1,8-cineole blood concentrations. Headspace SPME using 50 il whole blood collected from Possums dosed orally with 1,8-cineole (30 mg/kg) resulted in excellent sensitivity (quantitation limit 1 ng/ml) and reproducibility. Blood concentrations ranged between 1 and 1380 ng/ml. Calibration curves were prepared for two concentration ranges (0.05–10 and 10–400 ng/50 il) for the analysis of blood concentrations. Both calibration curves were linear (r2=0.999 and 0.994, respectively) and the equations for the two concentration ranges were consistent.
-
Biotransformation of 1,8-cineole in the brushtail Possum (Trichosurus vulpecula).
Xenobiotica, 2000Co-Authors: Rebecca Boyle, Stuart Mclean, Noel W. DaviesAbstract:1. The metabolic fate of 1,8-cineole was investigated in the brushtail Possum. Six Possums were fed an artificial diet to which 0.5% 1,8-cineole (wet weight) was added for 2 days. Urine and faeces were collected after the second day. A sample of each was extracted into ethyl acetate and analysed for metabolites. Both free and total levels of metabolites were identified by GC-MS and LC-MS and quantified by GC-MS. 2. The pattern of metabolite excretion was very complex in the brushtail Possum. Nineteen metabolites were found in total. Metabolites were categorized into four groups according to the oxidation they had undergone: hydroxycineoles (n = 3), cineolic acids (n = 2), dihydroxycineoles (n = 3) and hydroxycineolic acids (n = 11). No hydroxycineolic acid metabolites have been previously reported as metabolites of 1,8-cineole. 3. Fractional recovery of the ingested dose (2.4±0.5 g; mean±SD) was 0.44±0.14 (mean±SD) in 24 h. Sixty percent of excreted metabolites were hydroxycineolic acids, the most extensi...
