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Biomedical subjects

T E Carpenter

Publications and source records attributed to T E Carpenter.

At least 19 recordsLinked to original sources
PubMed1992

Serologic and bacteriologic test results after adult vaccination with strain 19 in three dairy herds infected with brucellosis.

Milk culture data and serologic test results were evaluated after adult vaccination with Brucella abortus strain 19 in cattle of 3 large California dairy herds infected with brucellosis. Strain-19 organisms were isolated by culture of milk from 1.9% of the vaccinated cows. Isolation of field strain of B abortus varied directly with magnitude of complement-fixation (CF) and rivanol titers. At time of milk culture, 74% of cows from which field strain was isolated had CF titer greater than or equal to 160, compared with 58% of cows from which strain 19 was isolated. Cows with CF titer greater than or equal to 160 at 2 months or greater than or equal to 80 to 4 months after adult vaccination were more likely to be correctly classified as reactors (on the basis of subsequent milk culture results and/or persistently high serologic titer) than were cows with lower CF titer at these times. Cows from which B abortus strain 19 was isolated from milk were more likely to maintain persistent serologic titer than were cows from which neither strain of B abortus was isolated.

Animals↗
PubMed1992

Using ribosomal RNA gene restriction patterns in distinguishing isolates of Pasteurella haemolytica from bighorn sheep (Ovis canadensis).

Pasteurella haemolytica isolates (n = 31) from two isolated captive herds of Rocky Mountain bighorn sheep (Ovis canadensis canadensis) were characterized and compared phenotypically (biotype, serotype, hemolytic activity) and by a genomic fingerprinting method known as ribotyping. Seven to nine distinct phenotypes were observed. Depending on the method used for serotyping, one to three phenotypes were common to both herds. Eighteen isolates, recovered from both herds, were non-hemolytic, biotype T, indirect hemagglutination assay serotype 4. Ribotyping, a method for highlighting genetically conserved deoxyribonucleic acid restriction site heterogeneity with a 32P-labelled Escherichia coli ribosomal ribonucleic acid probe, produced six to eight distinct ribotype pattern groups within the 31 P. haemolytica isolates, depending on the restriction enzyme used. In contrast to phenotypes, ribotypes appeared unique to each herd, and ribotyping helped to further differentiate some isolates of the same biotype and serotype. In addition, ribotyping provided an alternative means for evaluating relationships between isolates differing in hemolytic activity but which were otherwise phenotypically identical. We propose that ribotyping may be a useful adjunct to other bacterial characterization methods in studying the epizootiology of pasteurellosis in bighorn sheep.

Agglutination Tests↗
PubMed1991

Chagas' disease: risk factors for house infestation by Triatoma dimidiata, the major vector of Trypanosoma cruzi in Costa Rica.

The reduction of domiciliary infestation by insect vectors, the key to controlling Chagas' disease, depends on identification of housing features associated with infestation. In this study, log-linear modeling was used to reanalyze data collected in 1964-1968 from 371 houses on characteristics potentially associated with infestation by the vector Triatoma dimidiata in a Costa Rican town with endemic Chagas' disease. A possible increased risk of infestation was observed for houses with a dirt floor (as compared with houses with another floor type) and for houses in poor sanitary condition (as compared with houses in good sanitary condition). A new risk factor for house infestation, the presence of roof tiles, was identified; the odds of infestation for houses with a tile roof were 2.4 times greater than the odds for houses with a galvanized metal roof. This significantly increased risk is probably due to the harboring of T. dimidiata in stacks of spare tiles next to house walls rather than to the tile roofs themselves.

Chagas Disease↗
PubMed1991

Molecular epidemiology of Pasteurella multocida in turkeys.

Pasteurella multocida isolated from turkeys during an outbreak of fowl cholera was characterized by serotype and heterogeneity of genes encoding rRNA (ribotype) to investigate the epidemiology of the organism. Isolates were collected between October 1985 and July 1986. The M9 or Clemson University fowl cholera vaccine-like strain was detected in 17% of the flocks with fowl cholera. One particular strain, isolated only from breeder flocks, was recovered from 7 of the 10 breeder flocks examined in this study. Intracompany transmission appeared to be common, implying a failure in biosecurity. Circumstantial evidence indicated that in the field; the incubation period of P multocida in a turkey flock may be between 2 to 7 weeks. Wildlife did not appear to be an important reservoir of P multocida for turkeys during this study period. Ribotyping results tended to discount several of the possible interflock transmissions, as suggested by examination of serotyping results alone; however, serotyping in combination with ribotyping proved helpful in understanding the epidemiology of P multocida in turkeys.

Animals↗
PubMed1991

Use of a multivariable indexing score for hygiene variables in relation to egg production.

An indexing system for hygiene variables associated with egg production was developed by use of data collected from chicken flocks in southern California. The data were analyzed by factor and regression analysis. On the basis of our findings, hygiene index in relation to egg production consists of ventilation system, cooling system, manure removal, and truck movement. Flocks kept under natural ventilation produced, on the average, 2% more hen-day eggs than flocks kept under artificial ventilation. Flocks placed in houses with roof sprinklers produced 3.3% more hen-day eggs, compared with flocks placed in houses with inside foggers and pad. Flocks kept under the system of frequent removal of manure produced 2% more hen-day eggs than flocks kept under the system for which the manure was removed less frequently. Flocks kept in farms that restricted trucks collecting dead birds from entering the premises produced 3.4% more hen-day eggs than those that allowed such trucks to enter the farm.

Animal Husbandry↗
PubMed1991

Case control study of fowl cholera in meat turkeys in California from August 1985 through July 1986 [corrected].

From Aug 1985 through July 1986, 720 meat turkey flocks on 160 California premises were monitored and outbreaks of fowl cholera (Pasteurella multocida) were investigated. Data from 43 outbreak (case) flocks were compared with data from 43 nonoutbreak (control) flocks. Outbreak flocks, compared with control flocks, were more likely to be located on premises with higher maximal bird capacity and history of fowl cholera outbreaks. The overall impression was that flocks in larger, newer, more intensively managed premises were at greater risk of fowl cholera outbreaks than were other flocks.

Animals↗
PubMed1990

Financial analysis of pseudorabies control and eradication in swine.

Computerized decision-tree analysis and simulation modeling were used to evaluate control and eradication strategies for pseudorabies virus (PRV) in swine. Three alternative actions were considered for a hypothetical 100-sow, farrow-to-finish operation: (1) depopulation-repopulation, (2) test-and-removal of seropositives (T&R), and (3) vaccination (of the entire herd or of sows only). The expected monetary values for the vaccination and T&R alternatives were similar, which was consistent with the long-standing controversy over the best strategy for dealing with PRV. When the prevalence rate of PRV was less than or equal to 57%, T&R was found to be optimal; otherwise, vaccination of sows only was recommended. Sensitivity analysis was performed to determine how modifications in some of the original assumptions affected the expected monetary values of each strategy. When higher gross margins for the producer were assumed, T&R was preferred at all prevalence rates. Vaccination was preferred when lower gross margins, lower vaccination costs, or better protective effect of PRV vaccines on reproductive performance were assumed. The use of gene-deleted vaccines in conjunction with the T&R strategy was also evaluated. When this option was available, T&R was favored at any prevalence rate (T&R alone when the prevalence was less than or equal to 20%, or combined with gene-deleted vaccination at prevalences greater than 20%). Depopulation-repopulation was not the best option under any circumstance. Once formulated, a decision-tree analysis can be adapted to the prevailing economic or epidemiologic conditions; hence, it is a useful tool in the PRV decision-making process.

Animals↗
PubMed1990

Characteristics of Pasteurella multocida isolated from waterfowl and associated avian species in California.

Characteristics of Pasteurella multocida isolated from tissues of dead waterfowl and associated avian species found at 23 sites located in northern and central California, from January 1986 through January 1988 are reported. Two hundred ninety five isolates of P. multocida were obtained from 23 avian species. Most of the isolates belonged to the subspecies P. multocida multocida (63%), followed by P. multocida gallicida (37%), and by P. multocida septica (less than 1%). There appeared to be a higher prevalence of P. multocida multocida in Ross' geese (Chen rossi) and Snow geese (Chen coeruleus). All of the isolates belonged to somatic serotype 1, possessed the A capsule type and were susceptible to the 8 antimicrobial agents tested. None contained plasmid DNA.

Animals↗
PubMed1989

Decision-tree analysis of treatment alternatives for left displaced abomasum.

This study evaluates treatment alternatives for left displaced abomasum (LDA) in dairy cattle. The technique of decision-tree analysis was used to evaluate 3 treatment possibilities. A computerized spreadsheet decision tree was used for the evaluation. Results of this investigation suggested that surgical treatment had the highest expected monetary value. Closed surgical techniques had expected monetary values close to the surgical techniques. Rolling the cow had the lowest expected monetary value, but the expected monetary value for rolling was higher than the expected monetary value for selling. If an LDA recurs after treatment, surgical and closed surgical treatments are preferred over rolling. From this study, we can conclude that surgical and closed surgical treatment alternatives are preferred if expected monetary values are considered. Rolling is preferred over selling the cow. However, if an LDA recurs, selling the cow is preferred over rolling.

Abomasum↗
PubMed1989

Resistance to antimicrobial agents and prevalence of R plasmids in Pasteurella multocida from turkeys.

One hundred fifty-three isolates of Pasteurella multocida, representing the causative agent of 95% of all known outbreaks of fowl cholera occurring in California meat and breeder turkeys from August 1985 through February 1987, were examined for susceptibility to antimicrobial agents. Of the 153 isolates, 6 were shown to be resistant to one or more antimicrobial agents. Of the six resistant isolates, five contained R plasmids. All but one of the R plasmids were small (6 to 7 megadaltons) and nonconjugative, encoding resistance to tetracycline or kanamycin, streptomycin, and sulfonamides; the other was large (70 megadaltons) and conjugative, transferring resistance to kanamycin, streptomycin, sulfonamides, and tetracycline to P. multocida and Escherichia coli. The three plasmids encoding resistance to tetracycline alone appeared identical.

Animals↗
PubMed1989

Use of an rRNA probe and restriction endonuclease analysis to fingerprint Pasteurella multocida isolated from turkeys and wildlife.

Twenty-five isolates of the bacterium Pasteurella multocida were characterized (fingerprinted) phenotypically and genotypically in order to compare the abilities of various techniques to differentiate strains for epidemiologic studies of fowl cholera. Isolates were obtained over a 16-month period from turkeys dying from fowl cholera (six outbreak flocks) and from wildlife captured on premises with a history of the disease. The characteristics compared included (i) serotype, (ii) subspecies, (iii) antibiogram, (iv) presence of plasmid DNA, (v) restriction endonuclease analysis patterns of whole-cell DNA, and (vi) ribotype. Ribotyping, a method of highlighting DNA restriction site heterogeneity by using an rRNA probe, worked well for differentiating the strains of P. multocida when the majority of the other techniques could not. Ribotyping results correlated directly with and confirmed results obtained from restriction endonuclease analysis. Ribotyping demonstrated the presence of up to three strains of P. multocida in one outbreak flock, recurrence of a single strain in five of the flocks over an 11-month period, and the presence of common strains in turkeys and wildlife on the premises.

Animals↗
PubMed1988

Financial impact of transmissible gastroenteritis in pigs.

The financial impact of an epizootic of transmissible gastroenteritis in pigs was evaluated in a California sow herd through estimating growth, feed, and profit functions. Two groups of pigs were studied: pigs born before and surviving the epizootic (epizootic [E] pigs), and pigs born after the epizootic (postepizootic [PE] pigs). Short-term profits were maximized at 165 days for both groups of pigs, ranging from $47.14 for female E pigs to $60.32 for male PE pigs. Accordingly, it was concluded that pigs surviving or born shortly after a transmissible gastroenteritis epizootic are profitable to raise, if raised under management conditions similar to those in the study herd.

Animal Feed↗
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↗