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T E Carpenter

Publications and source records attributed to T E Carpenter.

At least 73 records · Page 4Linked to original sources
PubMed1987

Economics of Brucella ovis control in sheep: epidemiologic simulation model.

The epidemiology and economics of Brucella ovis control in a hypothetical, commercial sheep flock (100 rams and 2,500 ewes) were investigated. The investigation consisted of an epidemiologic simulation model, reported here, and a decision-tree analysis, reported in a companion paper. The epidemiologic model was designed to simulate the transmission and persistence of B ovis in a ram flock during the mating season as well as the nonmating (isolation) season. A constant contact rate was selected for the nonmating season and a varying contact rate was selected for the mating season to reflect changes in numbers of ewes in estrus. These contact rates were used to evaluate all possible combinations of 5 control alternatives for flock infection rates ranging from 0% to 38%. Vaccination was found to be more effective as a control strategy when the prevalence of flock infection was high (greater than 15%); however, it did not substantially reduce B ovis transmission when the prevalence of flock infection was low (less than 10%). The effect of increasing vaccine efficacy from 40% to 80% had minimal effect on incidence of new cases. The speed with which B ovis could be eradicated depended on the initial prevalence of infection and the screening tests used (palpation, semen testing for leukocytes, and ELISA). All combinations of screening tests verified the usefulness of palpation. Simulation model results indicated that it may be feasible to eradicate B ovis from flocks with moderate to high (10% to 38%) prevalence of infection by culling on the basis of 2 sequential tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Economics of Brucella ovis control in sheep: computerized decision-tree analysis.

The epidemiology and economics of Brucella ovis control in a hypothetical, commercial sheep flock (100 rams and 2,500 ewes) were investigated. The investigation consisted of an epidemiologic simulation model, reported in a companion paper, and a decision-tree analysis, reported here. It was predicted from the simulation model that B ovis could be eradicated successfully in 2 test periods (less than 1 year) from a flock by using intensive screening and culling. A computerized decision-tree program was used to determine the economically optimal control strategy among several alternatives. Two versions of the program were used to determine the optimal alternative, based on minimizing the expected monetary loss (deterministic) and minimizing the associated risk (stochastic). The economically optimal alternative was to screen the rams by means of palpation, semen testing, and ELISA prior to the mating season. Rams positive to any test were culled. After the mating season was completed, the optimal action was to use ELISA for the remaining rams and to cull all that were ELISA positive. The cost of this alternative was approximately $6,150, or less than one half the annual cost of a vaccination program ($12,800) or no program ($13,550). Continuing palpation and semen testing were considered worthwhile on the basis of detecting new cases of B ovis infection and in maintaining high flock fertility. Similarly, the cost of annual use of ELISA was small (approximately $100), compared with the potential cost of not detecting a new case of B ovis infection.

Animals↗
PubMed1986

Epidemiologic programs for computers and calculators. Decision-tree analysis using a microcomputer.

Decision analysis using decision trees enables the medical decision maker to simplify and solve complex problems. The technique, however, becomes cumbersome when the decision maker attempts to perform sensitivity analysis on the problem. This paper describes a computer program, written in PASCAL, to construct, modify, and perform deterministic and stochastic simulations and risk analysis on a hypothetical, decision-analysis problem. The deterministic version can be run on microcomputers with CP/M, PC-DOS, or MS-DOS operating systems, and the deterministic/stochastic version requires a PC-DOS or MS-DOS operating system.

Computers↗
PubMed1985

A field trial to assess the therapeutic and prophylactic effect of a foot rot vaccine in sheep.

An 18-week field trial was conducted on a sheep ranch to evaluate the therapeutic and prophylactic effect of a commercial foot rot vaccine. Two hundred sheep were included in the study, 100 with detectable foot rot lesions and 100 without. Approximately 50 sheep from each group were selected randomly and vaccinated twice against foot rot at a 6-week interval in the late spring 1984; the remaining sheep acted as nonvaccinated controls. Therapeutic effect of the vaccine was demonstrated by a cure rate of 53% in vaccinated, foot rot-affected sheep vs a cure rate of 19% in nonvaccinated, foot rot-affected sheep. Prophylactic effect of the vaccine was demonstrated by a foot rot prevalence at the end of the 18-week period of 9% for vaccinated sheep vs 53% for nonvaccinated sheep. Associations of foot rot lesions and vaccination with body condition were found to be significant, as was the association between foot rot lesions and mortality.

Animals↗
PubMed1984

Epidemiologic modeling using a microcomputer spreadsheet package.

Epidemiologic modeling has provided both researchers and students with a means of studying complex disease processes as well as making intervention recommendations to decision makers. To develop more than the most elementary model, however, it has become necessary to be well versed in a computer programming language. While this has deterred many modelers in the past, with microcomputers it is now possible to develop even complex models without significant investment of time spent in learning a computer language. In addition to being affordable, many microcomputers offer "canned" spreadsheet packages which are readily adapted for epidemiologic modeling. To demonstrate this, two models were developed and run using a microcomputer spreadsheet package: 1) the classic Reed-Frost model, and 2) a modified Reed-Frost model with two intermixing subpopulations.

Animals↗
PubMed1983

An economic evaluation of metabolic and cellular profile testing in calves to be raised in a feedlot.

The economic value of the metabolic and cellular profile test as a predictor of feedlot calves' performance was determined. The economic technique used in this evaluation was decision tree analysis. Results showed that in a case study evaluation such as this one, the metabolic and cellular profile test would not be recommended. Further, under the assumptions used, even if the test were perfected, the cost of the test should not exceed $2.79. The application of decision tree analysis demonstrated how questions concerning the economics of animal health issues may be formulated and solved.

Animal Husbandry↗
PubMedDate not supplied

Spatial heterogeneity of Escherichia coli DNA fingerprints isolated from cellulitis lesions in chickens.

Avian cellulitis in broiler chickens is characterized by subcutaneous lesions that result in economic losses because of the partial or complete condemnation of the carcasses at processing. Escherichia coli is the primary causative agent of this condition. Previous research with a biotyping system found that the E. coli of cellulitis origin were unique to each ranch, suggesting that these E. coli were endemic within the ranch environment. The objective of our study was to analyze the genetic variability of E. coli isolates associated with cellulitis. We analyzed the genetic relatedness of the isolates in relation to the houses, ranches, and complexes in which the broilers were grown. This analysis enabled us to assess the spatial heterogeneity, or genetic diversity on a spatial scale, of the isolates. Forty-nine broilers with cellulitis lesions were necropsied. These broilers came from six houses on four ranches on three complexes that had been placed with chicks from the same hatchery within a 2-wk period. Isolates of E. coli from the lesions were DNA fingerprinted by pulsed-field gel electrophoresis. Relatedness among isolates was determined with the Dice coefficient and an unweighted pair group method with average linkages cluster analysis. The complexes possessed isolates with a variety of DNA fingerprints, yet each complex appeared to have isolates with a unique set of DNA fingerprints. Isolates from the same complex tended to form clusters with similarity coefficients greater than 90%. Isolates from different complexes were genetically distinct. This heterogeneity at the level of the complex suggests that isolates were not disseminated from a source common to the complexes. The spatial heterogeneity of the E. coli isolates in this study implies an endemic population of cellulitis-associated E. coli exists in the broiler house environment.

Animals↗
PubMedDate not supplied

Transmission of Pasteurella multocida on California turkey premises in 1988-89.

Restriction endonuclease analysis (REA) of whole-cell DNA was used to determine possible sources of Pasteurella multocida for each outbreak of fowl cholera occurring in turkey flocks in eight commercial poultry companies in California from October 1988 to September 1989. Over this period, 179 isolates of P. multocida were obtained from dead turkeys in 80 meat and breeder flocks on 43 premises. P. multocida was isolated from wildlife on five premises. Isolates were characterized by subspecies, serotype, presence of plasmid DNA, and REA type. In 52 (65%) flocks, all isolates of P. multocida had the same REA pattern as the M9 live vaccine strain following digestion of DNA with the restriction enzyme SmaI. Field strains of P. multocida were obtained from 27 (34%) flocks, and one flock (1%) yielded both M9 and a field strain of the organism. REA of field strains of P. multocida revealed 17 different SmaI REA types. Based on matching SmaI REA types, potential sources of P. multocida were identified for 15 of the 28 flocks infected with field strains of the organism, and transmission between turkey premises was a possibility in only seven flocks.

Animals↗
PubMedDate not supplied

Restriction endonuclease analysis of Pasteurella multocida isolates from three California turkey premises.

Three California turkey premises that had repeated outbreaks of fowl cholera were studied for periods of 2 to 4 years. Using biochemical, serologic, plasmid DNA, and restriction endonuclease analyses of isolates of Pasteurella multocida from turkeys and wildlife on the premises, strains of the organism were found to be enzootic on two of the premises. On the third, a variety of strains of P. multocida were isolated from fowl cholera outbreak flocks.

Animals↗
PubMedDate not supplied

Serologic associations between fowl cholera and other diseases.

As part of a case-control study designed to identify fowl cholera risk factors, 2087 blood samples were collected from 71 California meat-turkey flocks. Samples were tested for antibodies to three mycoplasmas and four viruses pathogenic for turkeys. Flocks that had antibodies to Newcastle disease virus and/or Mycoplasma meleagridis had an increased risk of having an outbreak of fowl cholera. This information should prove useful for fowl cholera control programs in meat turkeys.

Animals↗
PubMedDate not supplied

Health survey of backyard poultry and other avian species located within one mile of commercial California meat-turkey flocks.

A survey was conducted to characterize domestic and exotic bird populations, estimate seroprevalence to selected disease agents, and describe health management practices on 62 premises containing "backyard" flocks located within one mile of 22 commercial California meat-turkey flocks participating in National Animal Health Monitoring System (NAHMS). Chickens were present on 56 backyard premises and turkeys on seven. Antibodies were identified against Mycoplasma gallisepticum, M. synoviae, M. meleagridis, Salmonella pullorum, Newcastle disease virus, avian encephalomyelitis virus, Bordetella avium, hemorrhagic enteritis virus, infectious bronchitis virus, and infectious bursal disease virus in 367 blood samples from 32 backyard premises. Twenty-two owners of backyard premises said they restricted visitor contact with their birds, and two required visitors to wear rubber boots and use boot disinfectant. Owners of seven premises used biologics and/or pharmaceutics for disease prevention. One family member worked on a commercial turkey ranch, but no other contact between owners, relatives, or employees and commercial poultry was reported.

Animals↗
PubMedDate not supplied

Homogeneity of characteristics of Pasteurella multocida isolated from turkeys and wildlife in California, 1985-88.

Five hundred twenty isolates of Pasteurella multocida, collected in California from September 1985 to November 1988, were characterized in the laboratory. Characteristics examined included serotype, capsular type, biotype (subspecies), and possession of plasmid DNA. Three hundred thirty-three isolates recovered from turkeys dying from fowl cholera, 88 isolates from liver turkeys in flocks with fowl cholera outbreaks in the recent past, and 99 isolates from wildlife captured on fowl cholera-outbreak and non-outbreak turkey premises were studied in this manner. Characteristics were fairly homogeneous among isolates, especially those obtained from turkeys. The majority of isolates were serotype 3,4, capsular type A, subspecies multocida, and lacked plasmid DNA. Common serotypes of isolates from turkeys and wildlife sampled on the same premises were noted in eight of 13 cases examined.

Animals↗
PubMedDate not supplied

Serum resistance as an indicator of virulence of Pasteurella multocida for turkeys.

Wildlife isolates of Pasteurella multocida, whose virulence for turkeys had previously been determined by intravenous inoculation, were characterized regarding their ability to survive incubation in fresh non-immune turkey serum. The relative virulence of the isolates was significantly associated with their ability to resist the bactericidal power of the serum as determined by standard plate counts following incubation. Organisms with a high survival value were more virulent; those with a low survival value were less virulent. A statistical model was specified and was successfully used to predict relative virulence of the P. multocida isolates. This method of assaying serum resistance was rapid, repeatable, and practical and could be performed with minimal laboratory equipment. Also studied was the serum resistance of seven serotype 3, 4 isolates obtained from the lungs of M9-vaccinated turkeys from seven flocks experiencing increased mortality due to fowl cholera. These isolates were shown to be identical to the M9 vaccine by restriction endonuclease analysis of chromosomal DNA. Six of the seven isolates had higher serum survival values than the original M9 vaccine.

Animals↗