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G Gettinby

Publications and source records attributed to G Gettinby.

At least 19 recordsLinked to original sources
PubMed2006

A simulation model to assess herd-level intervention strategies against E. coli O157.

A simulation model of a herd of grazing cattle, which has been developed to provide insight into the infection dynamics of E. coli O157 is described. The spatially explicit model enables the modelling of the infection transmission processes to be realistically addressed under field management conditions. The model is used to explore the efficacy of various potential control strategies in reducing the levels of within-herd infection. These measures include restricting the size of herds, niche engineering, improving housing hygiene and vaccination. While a vaccination strategy remains a hypothetical option, it has the potential to be particularly effective. It is likely that the most successful strategy will involve the implementation of a combination of measures.

Animals↗
PubMed2006

Assessing the efficacy of within-animal control strategies against E. coli O157: a simulation study.

A stochastic simulation model was used to assess the efficacy of potential measures to control the levels of Escherichia coli O157 within the bovine host. The model described E. coli O157 population sizes at several sites along the bovine gut and therefore only interventions that operate at an individual animal level could be evaluated. In order to use the model to evaluate the control strategies, it was necessary to make assumptions about how each strategy affected E. coli O157 populations in vivo. The within-animal conditions under these control strategies were modelled by adjusting the growth rates of E. coli O157 at specific sites of interest in the gut, based on these assumptions. The model simulated the population dynamics of an initial dose of E. coli O157 inoculated into an animal in the presence of inhibitory probiotics or antibiotics, bactericidal antibiotics or probiotics, and following fasting. Of the control strategies considered, the use of inhibitory probiotics appeared most promising and continued development of a suitable product is to be encouraged.

Animals↗
PubMed2006

A simulation model for the study of the within-animal infection dynamics of E. coli O157.

Escherichia coli 0157 can cause serious illness, even death, in humans. There is some consensus that the main reservoirs of this harmful bacterium are the rumens and intestines of cattle. Hence, a stochastic model of the bovine gut was developed to investigate the in vivo population dynamics of E. coli O157. Because bacterial numbers can reach minimal levels, a stochastic system was considered, with a birth-death process being used to represent bacterial growth and decay dynamics throughout the gastrointestinal tract. Reinfection through ingestion of bacteria present in the environment was allowed to occur and the required clustered distribution of inter-event times was implemented through the use of a random hazard doubly stochastic Poisson process. Due to the inclusion of multiple compartments, a feedback mechanism and an interest in the non-equilibrium dynamics of the process, it was not possible to obtain an analytical representation of the process and therefore, a simulation study was used to obtain results. The within-animal model can be used to explore the efficacy of control measures which act at an individual animal level.

Animals↗
PubMed2006

A stastistical system for detecting Salmonella outbreaks in British livestock.

Worldwide, early detection systems have been used in public health to aid the timely detection of increases in disease reporting that may be indicative of an outbreak. To date, their application to animal surveillance has been limited and statistical methods to analyse human health data have not been viewed as being applicable for animal health surveillance data. This issue was investigated by developing an early detection system for Salmonella disease in British livestock. We conclude that an early detection system, as for public health surveillance, can be an effective tool for enhanced surveillance. In order to implement this system in the future and extend it for other data types, we provide recommendations for improving the current data collection process. These recommendations will ensure that quality surveillance data are collected and used effectively to monitor disease in livestock populations.

Animals↗
PubMed2005

Herd-level risk factors associated with tuberculosis breakdowns among cattle herds in England before the 2001 foot-and-mouth disease epidemic.

A case-control study of the factors associated with the risk of a bovine tuberculosis (TB) breakdown in cattle herds was undertaken within the randomized badger culling trial (RBCT). TB breakdowns occurring prior to the 2001 foot-and-mouth disease epidemic in three RBCT triplets were eligible to be cases; controls were selected from the same RBCT area. Data from 151 case farms and 117 control farms were analysed using logistic regression. The strongest factors associated with an increased TB risk were movement of cattle onto the farm from markets or farm sales, operating a farm over multiple premises and the use of either covered yard or 'other' housing types. Spreading artificial fertilizers or farmyard manure on grazing land were both associated with decreased risk. These first case-control results from the RBCT will be followed by similar analyses as more data become available.

Animals↗
PubMed2005

A mathematical model of the growth of sea lice, Lepeophtheirus salmonis, populations on farmed Atlantic salmon, Salmo salar L., in Scotland and its use in the assessment of treatment strategies.

Sea lice are a persistent problem for farmed and wild salmonid populations. Control can be achieved through the use of veterinary medicines. A model was developed to describe the patterns of sea lice infection on salmon farms in Scotland and to predict the likely effect of various treatment strategies. This model takes into account development rates and mortality using compartments representing life history stages and external infection pressure. The national sea lice infection pattern was described using parameters representing stage survival, background infection levels and egg viability rates. The patterns observed across farms varied greatly and the model gave broad agreement to observed trends with different parameters being required in the model for sites using hydrogen peroxide and cypermethrin treatments. The parameter estimates suggest that the background infection pressure on sites where cypermethrin was administered was higher than for those using hydrogen peroxide. Both models had comparable magnitudes of sensitivity with survival from one stage to another being the most sensitive parameter, followed by feedback rates at which gravid females produce eggs, with background infection levels the least sensitive. The effect of different cypermethrin treatment strategies was assessed using the model. Increasing treatments in a production cycle gave more effective control. However, the model showed that timing of treatments is most important if sea lice are to be effectively controlled.

Animals↗
PubMed2004

Examination of serum total IgG1 concentration in atopic and non-atopic dogs.

In this study, serum immunoglobulin G1 (IgG1) concentrations were examined in atopic and non-atopic dogs receiving different levels of parasite control. Significantly lower serum total IgG1 concentrations were found in non-atopic dogs receiving stringent parasite control than in atopic dogs or non-atopic dogs receiving less stringent parasite control. Examination of serum total IgG1 concentrations of atopic dogs after six months of allergen specific immunotherapy (ASIT) showed a significant increase in serum total IgG1 concentrations. It is proposed that serum total IgG1 concentrations are affected by parasitism, atopic dermatitis and ASIT.

Allergens↗
PubMed2004

Potential use of vaccination in cattle or badgers to control bovine tuberculosis.

The application of regular herd testing to identify and remove infected animals has proved to be a highly successful method of controlling bovine tuberculosis (TB) in many parts of the world. However, in some countries, notably the United Kingdom, Ireland and New Zealand, the disease has continued to pose a significant problem, despite intensive herd testing. Persistence of disease in these countries is associated with the presence of wildlife reservoirs of infection. Attempts to control bovine TB by culling of wildlife have been, at best, only partially successful and have proved difficult to sustain. This has led to considering of vaccination either of wildlife or cattle as a potential control measure. However, there are a number of obstacles that need to be overcome before vaccination can be considered a practical option. Vaccine efficacy, methods used for vaccine delivery in wildlife, potential interference of vaccination with diagnostic tests for cattle and appropriate design of field trials are among the issues that need to be addressed.

Animals↗
PubMed2003

Identifying epidemiological factors affecting sea lice Lepeophtheirus salmonis abundance on Scottish salmon farms using general linear models.

The variation in Lepeophtheirus salmonis sea lice numbers across 40 Scottish salmon farm sites during 1996 to 2000 was analysed using mean mobile abundance for 3 important 6 mo periods within the production cycle. Using statistical regression techniques, over 20 management and environmental variables suspected to have an effect on controlling lice populations were investigated as potential risk factors. The findings and models developed provide a picture of mobile L. salmonis infestation patterns on Scottish farm sites collectively. The results identified level of treatment, type of treatment, cage volume, current speed, loch flushing time and sea lice levels in the preceding 6 mo period to be key explanatory factors. Factors such as stocking density, site biomass, water temperature and the presence of neighbours, previously cited to be important correlates of sea lice risk from analysis of individual sites over time, were not found to be important. Variation in mobile abundance in the first half of the second year of production could be adequately explained (adjusted R2 between 55 and 72%) by the recorded data, suggesting that there is scope for management to control L. salmonis abundance, though much of the variation remains unexplained.

Animals↗
PubMed2003

Studies of serum total immunoglobulin E concentrations in atopic and non-atopic dogs.

The serum total immunoglobulin E (IgE) concentrations of two groups of atopic dogs and three groups of non-atopic dogs were compared. There was a wide range of concentrations with a high degree of overlap between the groups. The serum total IgE concentrations of a group of 15 non-atopic racing greyhounds were significantly higher than those of all the other groups. Atopic and non-atopic dogs receiving stringent parasite control treatments could not be differentiated on the basis of their serum total IgE concentrations. In the non-atopic dogs there was no correlation between their serum total IgE concentrations and the number of allergen-specific positive results obtained in an ELISA, or between their serum total IgE concentrations and their age.

Aging↗
PubMed2003

A comparison of epidemiological patterns of salmon lice, Lepeophtheirus salmonis, infections on farmed Atlantic salmon, Salmo salar L., in Norway and Scotland.

This paper examines two large national data sets collected over several years and contrasts the patterns of sea lice, Lepeophtheirus salmonis (Krøyer, 1837), infections, the use of treatments and the occurrence of chalimus peaks between Norwegian and Scottish farms. Infection levels in Scotland were significantly higher in general over the period under study. For the chalimus stage group in the first quarter of the year, Norwegian mean abundance stayed below 10 lice per m2 while Scottish means reached 45 lice per m2 of fish skin per m3 of water. Both countries had more chalimus in summer than at other times of year, but in the last 3 months of the year Scottish fish had, on average, two to four times as many chalimus as Norwegian fish. Peaks of chalimus abundance were more frequent in Scotland, particularly in winter, but the most prominent peaks occurred in summer in both countries. In Scotland a marked mid-year build-up of mobile pre-adult and adult stages was seen, and both countries showed a tendency for mobile counts on the second year fish to increase towards the end of the year. Scottish fish carried, on average, three times as many mobile lice per m2 of skin as Norwegian fish in the last 3 months of the year. The difference in lice loads was reflected in the greater use of veterinary medicines on Scottish farms. The higher infection levels in Scotland may be due to shallower and more enclosed water bodies used for farming, smaller and shallower pens, differences in sea water temperatures or in access to appropriate medication. The results highlight the importance of ensuring that effective veterinary medicines are available in the UK for the control of infection.

Animals↗
PubMed2003

In vitro and ex vivo effects of the phosphodiesterase 4 inhibitor, rolipram, on thromboxane production in equine blood.

Phosphodiesterase 4 (PDE4) inhibitors have been shown to inhibit equine neutrophil function in vitro and may be of benefit in recurrent airway obstruction (RAO), an allergy-based respiratory disease characterized by inflammatory cell recruitment and activation within the lungs following exposure of susceptible horses to allergens in mouldy hay. The aim of this study was to evaluate the inhibitory effects of the PDE4 inhibitor, rolipram, in an in vitro assay of thromboxane (Tx) production. The assay was then used to monitor the activity of this compound in vivo in normal and RAO-affected horses. Rolipram and the structurally distinct PDE4 inhibitor, denbufylline, attenuated both lipopolysaccharide (LPS)-induced and unstimulated Tx production in blood from normal horses. Thromboxane production appeared to involve a calcium-dependent interaction between leucocytes and platelets (LPS-induced Tx production = 2.3 +/- 0.4, 4.5 +/- 1.1 and 20.8 +/- 3.6 ng/mL for platelets, leucocytes and blood, respectively) and rolipram-inhibited Tx production via an effect on leucocytes. Inhibition of ex vivo LPS induced Tx production was detected after intravenous administration of rolipram (5 microg/kg) to normal ponies. This dose did not significantly affect either lung function or neutrophil accumulation when administered to three horses with clinical signs of RAO. This study suggests that inhibition of Tx production in equine blood can be used to measure PDE4 activity. However, PDE4 inhibitors with improved therapeutic profiles are required for evaluation in RAO.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2002

Veterinary Products Committee working group report on feline and canine vaccination.

* The working group was set up by the Veterinary Products Committee in response to current concern in both the public domain and in the scientific community about possible health risks related to the routine vaccination of cats and dogs. The working group concluded that vaccination plays a very valuable role in the prevention and control of the major infectious diseases in cats and dogs. Although adverse reactions to vaccination, including lack of efficacy, occasionally occur, the working group concluded that the overall risk/benefit analysis strongly supports their continued use. * Although for some diseases there is evidence of a longer duration of immunity following vaccination than the one year which is typically recommended on the product literature, there is currently insufficient information to propose revaccination intervals other than those proposed by the manufacturer and approved by the regulatory process. * Notwithstanding this, in view of the occasional occurrence of adverse reactions, the working group recommends that the product literature indicates that the regime for booster vaccinations is based on a minimum duration of immunity rather than a maximum. The working group further recommends that the product literature should state that a risk/benefit assessment should be made for each individual animal by the veterinary surgeon in consultation with the owner with respect to the necessity for each vaccine and the frequency of its use. * The evidence suggests that cats appear to be susceptible to the occasional development of sarcomas at sites of injection and there is some further evidence to suggest that, although other products may be involved, this may be more associated with the use of vaccines containing aluminium-based adjuvants. The working group therefore recommends that a generic warning to this effect should appear on the product literature for all feline vaccines administered by injection. The working group also highlighted the need for professional and educational bodies in the UK to bring to the attention of veterinary practitioners appropriate methods for prevention, diagnosis and treatment of this serious condition. * The working group considered in depth the monitoring of adverse reactions, including the advantages and disadvantages of surveillance schemes. A range of options for carrying out further epidemiological (analytical) studies was also considered. However, the working group emphasised that surveillance schemes, and the UK Veterinary Medicines Directorate (VMD) Suspected Adverse Reaction (SAR) Surveillance Scheme in particular, provided a very valuable resource. The large database within the VMD scheme (collected since 1985) was analysed as part of this report. Figures were derived in terms of incidence (reporting rate) of certain clinical signs per 10,000 doses, and risk factors as identified by statistical analysis. However, due to a number of constraints, the analysis was not fully comprehensive and the interaction of possible risk factors was not determined. * Product-related control charts were developed in order to detect changes in incidence rates of adverse reactions (per 10,000 doses sold) both within and between different vaccines. Such charts provide a powerful way to detect changing trends in incidence and, when used in conjunction with product characteristics, they may identify possible causes. In general, the data showed that the incidence of adverse reactions to cat and dog vaccines per 10,000 doses of product sold was relatively low. Although under-reporting is a feature of such surveillance schemes, it does appear that, overall, vaccination of cats and dogs should be considered safe and effective. * Finally, the working group was conscious, while preparing this report, of the extensive media coverage that has been given to the issue of the safety of human vaccines, in particular the mumps, measles and rubella (MMR) vaccine. The working group emphasises that the conclusions and recommendations included in this report relate only to the vaccines used in cats and dogs. The issues identified are specific to the diseases and species examined and no attempt should be made to draw analogous conclusions in relation to vaccines administered to humans.

Animal Welfare↗
PubMed2002

The efficacy of Salenvac, a Salmonella enterica subsp. Enterica serotype Enteritidis iron-restricted bacterin vaccine, in laying chickens.

The protective effect of two vaccination regimes using Salenvac, a commercially available iron-restricted Salmonella enterica subsp. Enterica serotype Enteritidis PT4 bacterin vaccine, was verified in laying birds. Immunization was intramuscular at 1 day old and again at 4 weeks of age (V2), or at 1 day and 4 weeks with a third dose at 18 weeks of age (V3). Challenge S. Enteritidis (5 to 7.5); x 10(7) colony forming units) was given intravenously at 8, 17, 23, 30 and 59 weeks of age. For all age groups, both vaccination regimes reduced significantly the number of tissues and faecal samples that were culture positive for the challenge strain. For laying birds, fewer eggs (P < 0.001) were culture positive for S. Enteritidis after challenge from vaccinated laying birds (56/439 batches of eggs) than unvaccinated birds (99/252 batches). The data give compelling evidence that the vaccine is efficacious and may contribute to the reduction of layer infection and egg contamination.

Animals↗
PubMed2001

A longitudinal study of disease incidence and case-fatality risks on small-holder dairy farms in coastal Kenya.

A longitudinal study was carried out in the coastal lowlands coconut-cassava agro-ecological zone of Kaloleni Division, Coast Province, Kenya between June 1990 and December 1991 to estimate disease incidence and cause-specific case-fatality risk in an average of 120 cattle in 26 small-holder dairy herds kept in two grazing-management systems. East Coast fever (ECF) was the predominant disease diagnosed; the mean monthly incidence rate was 2.5 and 6.9% in animals < or = 18 months of age under stall-fed and herded-grazing systems, respectively. In cattle > 18 months of age, the monthly incidence rate was < 1%. The 6-month ECF incidence rate was 20+/-8% (S.E.) in the stall-feeding system compared with 39+/-7% in the herded-grazing systems. There was a gradual increase in antibody prevalence with age to over 90% in cattle over 18 months of age in herded-grazing systems, whilst less than a third of cattle in the stall-feeding systems were sero-positive at any age. Overall accumulated mortality to 18 months of age was estimated to be 56%. Annual mortality in cattle > 18 months averaged 9%. Cattle managed in the herded-grazing system had a 60% higher mortality, although not significantly so, than those fed in stalls. Deaths due to ECF accounted for over two-thirds of the deaths. ECF was then the major disease constraint to small-holder dairy production in the coconut zone of coastal Kenya. Clinical cases occur the whole year round (especially in young stock)--despite apparent tick control, and in both herded-grazing and stall-feeding system.

Age Factors↗