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Biomedical subjects

S C Hathaway

Publications and source records attributed to S C Hathaway.

At least 37 records · Page 2Linked to original sources
PubMed1992

Control of Leptospira hardjo infection in beef cattle by whole-herd vaccination.

A whole-herd vaccination programme to control Leptospira hardjo infection was applied to a closed herd of approximately 800 beef cattle on the island of Luing in Scotland. An experimental vaccine was produced and the herd was vaccinated annually for five years. Progress was monitored by means of a catalytic model using data for age-specific serological prevalences and geometric mean titres. Any cattle introduced to the herd were subject to antibiotic treatment and quarantine, and at the end of the trial the whole herd was treated prophylactically with antibiotics to minimise the risk of residual infection. There was a progressive right shift in age-specific serological prevalences, and by the end of the trial all young stock entering the breeding herd were seronegative. The age-specific geometric mean titres demonstrated the cessation of an endemic cycle of hardjo infection in the herd. Birth cohort analysis supported the serological evidence of a high level of control, and bacteriological monitoring at the end of the trial indicated that hardjo had been eliminated from the herd.

Age Factors↗
PubMed1991

Meat inspection in New Zealand: prospects for change.

Regulatory authorities are facing increasing challenges with respect to the newly-recognised public health risks associated with meat products. Meat inspection resources should be allocated according to their maximum ability to reduce food-borne hazards, rather than according to the classical rules of meat inspection. Scientific evaluation of routine post-mortem inspection procedures for each class of livestock, introduction of the Hazard Analysis Critical Control Point approach to process control, on-line testing for microbiological hazards and residues, and effective management of production, processing and inspection data are central to this process. The meat inspection system that has evolved in New Zealand reflects a response to non-scientific forces such as market requirements and industrial practices rather than scientific discipline. In the future, the daily routine of meat inspectors will be extended well beyond their current slaughterfloor responsibilities, and veterinarians will require specialist skills. Science should be the basis for international food regulation and policy concepts such as equivalence or mutual acceptance are achievable on this basis.

Journal Article↗
PubMed1991

The application of risk assessment methods in making veterinary public health and animal health decisions.

The newly emerging discipline of quantitative risk assessment has wide application in the field of veterinary public health and animal health. Regulatory authorities are increasingly faced with public policy decisions that must assess the risks of new technology or practices relative to the potential benefits, thereby establishing a level of acceptable risk. The elements of risk are a choice of action, a probability of loss and a magnitude of loss. Perceived risk and actual risk are seldom equivalent; adoption of the methodologies used in technological and human health risk assessments will allow veterinary regulators to make better decisions. Determination of levels of acceptable risk are increasingly dependent on quantitative models, and examples are presented for evaluation of different post-mortem meat inspection systems, estimating disease risks associated with animal embryo transfer and formulating national border protection strategies. All models have some degree of subjectivity, and the decisions made by regulators and risk managers should incorporate a wide knowledge of the risk assessment process, as well as the conditions of use that will occur in the real world.

Animals↗
PubMed1990

A risk-assessed evaluation of postmortem meat inspection procedures for ovine thysanosomiasis.

A risk assessment model was used to evaluate 4 meat inspection procedures for routine detection of Thysanosoma actinioides, a tapeworm that commonly infests the bile duct system of adult sheep in the United States. The overall sensitivities of different procedures ranged from 11.96 to 58.70%, and the nondetection rates per 1,000 viscera sets that passed inspection ranged from 38 to 77. On the basis of performance attributes for each procedure produced by the risk assessment model, the consumer was exposed to an aesthetic defect that was in 9 to 17 of every 1,000 livers passed for human consumption. The amount of wastage was also identified (3 to 39 livers/1,000 passed). Viewing of the incision site of the common hepatic duct was the most preferable routine inspection procedure, and matched pair analysis revealed that there was no additional benefit in combining this procedure with routine expression of a portion of bile from the gallbladder.

Animals↗
PubMed1989

Impact of ovine meat inspection systems on processing and production costs.

The efficiency and cost-effectiveness of government-regulated meat inspection systems are under review in a number of countries. A post mortem organoleptic meat inspection programme is the most costly component of an inspection system and the procedures applied to a particular class of livestock should be appropriate to the spectrum and prevalence of diseases and defects present in each geographical region. Awareness of the impact of specific inspection requirements on processing costs, the application of integrated quality management principles and the development of programmes that disseminate information on diseases and defects and reward the producer of high-quality carcases, are all features of an efficient and cost-effective inspection system.

Animals↗
PubMed1987

Serological studies on British isolates of the Sejroe serogroup of leptospira. II. An evaluation of the factor analysis method of identifying leptospires using strains belonging to the Sejroe serogroup.

Twelve British isolates of leptospira belonging to the Sejroe serogroup were examined using a series of six factor sera prepared by a number of different absorption methods. Ten of the isolates were identified as Leptospira interrogans serovar hardjo and two as L. interrogans serovar saxkoebing. These isolates had previously been identified using the cross agglutination absorption method.

Agglutination Tests↗
PubMed1987

Serological studies of British leptospiral isolates of the Sejroe serogroup. III. The distribution of leptospires of the Sejroe serogroup in the British Isles.

Some 94 strains of leptospires belonging to the Sejroe serogroup isolated in the British Isles were identified to the serovar level using specific factor sera. Seventy strains were identified as Leptospira interrogans serovar hardjo, 66 from cattle, 2 from pigs and 1 each from a sheep foetus and a human. Twenty-four strains were identified as L. interrogans serovar saxkoebing, most strains were isolated from either wood mice, bank or field voles but strains were also isolated from badgers, a fox and a dog.

Animals↗
PubMed1986

Problems associated with the serological diagnosis of Leptospira interrogans serovar hardjo infection in bovine populations.

Data combining sequential bacteriology and serology from a longitudinal study of a dairy herd were used to demonstrate the limitations of serology as a diagnostic method in cross-sectional sampling of bovine populations. Whole-herd point serological prevalences showed considerable variation over a two-year sampling period (38.8 to 76.2 per cent), and this was mainly due to varying age-specific prevalence. Owing to the rapid decline in titres and the varying persistence of infection, point serological prevalences failed to approximate to cumulative infection rates (either past or present) at different times of the year. A higher estimate of the number of susceptible animals in the herd than is the case results in inaccurate information on true incidence rates and can confuse assessments of the susceptibility of different age groups, especially if only small numbers are sampled. A sampling exercise demonstrated that a 10-cow sample usually provided little useful information other than establishing the presence or absence of hardjo in the herd. Increasing the sample size markedly improved epidemiological information, investigations of clinical disease, assessments of vaccination needs and public health tracebacks. Preferably 10 sera from each of the yearling, first calver, second calver and older age groups should be tested. Serology was an inadequate indicator of infection in individual animals. Group geometric mean titres taken from a mean serological response curve were shown to have limited application in the interpretation of field data, unless infection had occurred in the previous two months.

Animals↗
PubMed1986

Serological studies on British leptospiral isolates of the Sejroe serogroup. I. The identification of British isolates of the Sejroe serogroup by the cross agglutinin absorption test.

Using the cross agglutinin absorption test 12 British leptospiral isolates of the Sejroe serogroup were identified to serovar level. Six strains isolated from cattle, two from pigs and one from a human were identified as Leptospira interrogans serovar hardjo. Two isolates from wildlife were identified as Leptospira interrogans serovar saxkoebing. One further strain isolated from wildlife closely resembled serovar saxkoebing, but specific identification was not possible. These are the first reported isolations of serovar saxkoebing in the United Kingdom. The problems associated with the cross agglutinin absorption test, and possible alternative typing procedures are discussed.

Agglutination Tests↗
PubMed1985

Differentiation of reference strains of leptospires of the Pomona serogroup by cross-agglutination absorption and restriction endonuclease analysis.

The serological classification of all reference strains that have been described as representing separate serovars of Leptospira interrogans within the Pomona serogroup was investigated using cross-agglutination absorption and bacterial restriction endonuclease analysis (BRENDA). Comparative cross-agglutination absorption studies indicated that cornelli CB, monjakov Monjakov and kennewicki LT1026 were homologous with pomona Pomona, and dania K1 and tsaratsova B81/7 were homologous with mozdok 5621. BRENDA confirmed these results, except that pomona Pomona and monjakov Monjakov showed a difference in the high molecular weight region. It is proposed that four serovars be currently recognised within the Pomona serogroup: pomona, mozdok, proechimys and tropica. The relative merits of the use of cross-agglutination absorption and BRENDA with respect to identification of Pomona serogroup isolates are discussed.

Agglutination Tests↗
PubMed1985

Identification by cross-agglutination absorption and restriction endonuclease analysis of leptospires of the Pomona serogroup isolated in the United Kingdom.

Five strains of Leptospira interrogans isolated in the United Kingdom and belonging to the Pomona serogroup were subjected to cross-agglutination absorption and bacterial restriction endonuclease DNA analysis (BRENDA) for their identification. British isolates were compared with reference strains representing the known serovars in the Pomona serogroup and also with isolates of the Pomona serogroup obtained from other countries. Three strains isolated from wildlife in England produced equivocal results when the cross-agglutination absorption and BRENDA results were compared. According to the World Health Organisation definition of a serovar the three English strains represented two new serovars, whereas by BRENDA all three had DNA electrophoresis patterns indistinguishable from serovar mozdok. Serovar pomona has not as yet been isolated in Great Britain and the epidemiology of the Pomona serogroup infections that have been detected by serology suggests that a serovar such as mozdok, maintained by wildlife, may be the causal agent. Two strains isolated in Northern Ireland were identified as pomona by the cross-agglutination absorption test. Further studies are needed to investigate the homogeneity of field and reference strains that are designated as pomona using the cross-agglutination absorption test.

Agglutination Tests↗
PubMed1984

Possible role of leptospires of the Pomona serogroup in sporadic bovine abortion in the south west of England.

An investigation of a small outbreak of abortion in mixed-age cows in a dairy herd in Somerset produced circumstantial evidence that a leptospire belonging to the Pomona serogroup was the causative agent. Although the initial epidemic involved more than 30 per cent of the herd, agglutination titres did not persist in the majority of animals and bacteriological monitoring produced no evidence that this leptospire could establish endemic infection in dairy cattle. An isolate recovered from the kidney of a cow which aborted was found to be similar to mozdok, a serovar maintained by free-living species in continental Europe, and it is probable that free-living species also maintain the Pomona serogroup organisms that have been isolated in England. Clinical disease caused by infection of domestic stock with Pomona serogroup organisms other than pomona has not been recognised in other countries but this may be because of the presence of endemic infection with pomona, a serovar that causes a very similar clinical and serological response.

Abortion, Veterinary↗
PubMed1984

Infection by leptospires of the Pomona serogroup in cattle and pigs in south west England.

Leptospires belonging to the Pomona serogroup were isolated from calves involved in two outbreaks of acute haemolytic disease which were characterised by jaundice, haemoglobinuria and high death rates. Retrospective case studies in which serological evidence of Pomona serogroup infection was found are also presented. Serovar pomona is the leptospire of the Pomona serogroup most commonly incriminated in clinical disease in domestic species, but the organisms isolated in this study were antigenically different to pomona and may represent a new serovar. The limited information available on the epidemiology of sporadic infection with leptospires of the Pomona serogroup in domestic species in the south west of England supports the contention that a serovar other than pomona is involved.

Animals↗
PubMed1983

Infection of free-living carnivores with leptospires of the Australis serogroup.

Leptospires belonging to the Australis serogroup were isolated from badgers (Meles meles), mink (Lutreola lutreola) and a fox (Vulpes vulpes). Most isolates were identified by cross-agglutination absorption as serovar muenchen but one isolate from a fox from Surrey and one isolate from a badger from Northern Ireland were identified as serovar bratislava. Maintenance of serovar muenchen by a wide range of free-living species is an ecological condition unique to Great Britain.

Animals↗