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  • Author or Editor: E. Robert Atwill x
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Abstract

Objective—To evaluate seasonal patterns and risk factors for Escherichia coli O157:H7 in feces in a beef cattle herd and determine strain diversity and transition in E coli over time by use of multiple-locus variable-number tandem-repeat analysis (MLVA) and pulsed-field gel electrophoresis (PFGE).

Sample Population—456 samples of freshly passed feces collected over a 1-year period from cattle in a range-based cow-calf operation located in the foothills of the Sierra Nevada Mountains in California.

Procedures— E coli O157:H7 was recovered from feces by use of immunomagnetic separation and 2 selective media. Virulence factors were detected via reverse transcriptase-PCR assay. Escherichia coli O157:H7 isolates were subtyped with MLVA and PFGE. Prevalence estimates were calculated and significant risk factors determined. A dendrogram was constructed on the basis of results of MLVA typing.

Results—Overall prevalence estimate for E coli O157:H7 was 10.5%, with the prevalence lowest during the winter. Mean temperature during the 30 days before collection of samples was significantly associated with prevalence of E coli O157:H7 in feces. Nineteen MLVA and 12 PFGE types were identified.

Conclusions and Clinical Relevance—A seasonal pattern was detected for prevalence of E coli O157:H7 in feces collected from beef cattle in California. Subtyping via MLVA and PFGE revealed a diversity of E coli O157:H7 strains in a cow-calf operation and noteworthy turnover of predominant types. Given the importance of accurately determining sources of contamination in investigations of disease outbreaks in humans, MLVA combined with PFGE should be powerful tools for epidemiologists. (Am J Vet Res 2010;71:1339–1347)

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in American Journal of Veterinary Research

Abstract

Objective—To estimate cat population size, management, and outside fecal deposition and evaluate attitudes of cat owners and nonowners to stray animal control, water pollution, and wildlife protection.

Design—Cross-sectional survey.

Sample Population—294 adult residents of Cayucos, Los Osos, and Morro Bay, Calif.

Procedures—Telephone survey.

Results—The region's cat population was estimated at 7,284 owned and 2,046 feral cats, and 38% of surveyed households owned a mean of 1.9 cats/household. Forty-four percent of cats defecated outside >75% of the time. Annual fecal deposition (wet weight) by owned cats in the 3 communities was estimated to be 77.6 tonnes (76.4 tons). Cat owners were more likely to oppose cat licensing and impounding stray cats and support trap-neuter-return for stray cats and less likely to be concerned about water pollution, than were noncat owners.

Conclusions and Clinical Relevance—Feral cats represented a sizeable proportion (22%) of the free roaming cats in this area and could be contributing 30.0 tonnes (29.5 tons) of feces to the environment per year. However, feral cats are not the principal source of fecal loading because owned cats defecating outdoors contribute an estimated 77.6 tonnes (76.4 tons) or 72% of the annual outdoor fecal deposition.

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvumo ocysts.

Design—Clinical trial.

Animals—75 calves.

Procedure—Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered PO on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week.

Results—Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea.

Conclusions and Clinical Relevance—Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C parvum oocysts could be reduced. (J Am Vet Med Assoc 2003;223:839–845)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To estimate the analytic sensitivity of microscopic detection of Toxoplasma gondii oocysts and the environmental loading of T gondii oocysts on the basis of prevalence of shedding by owned and unowned cats.

Design—Cross-sectional survey.

Sample Population—326 fecal samples from cats.

Procedures—Fecal samples were collected from cat shelters, veterinary clinics, cat-owning households, and outdoor locations and tested via ZnSO4 fecal flotation.

Results—Only 3 (0.9%) samples of feces from 326 cats in the Morro Bay area of California contained T gondii–like oocysts. On the basis of the estimated tonnage of cat feces deposited outdoors in this area, the annual burden in the environment was estimated to be 94 to 4,671 oocysts/m2 (9 to 434 oocysts/ft2).

Conclusions and Clinical Relevance—Despite the low prevalence and short duration of T gondii oocyst shedding by cats detected in the present and former surveys, the sheer numbers of oocysts shed by cats during initial infection could lead to substantial environmental contamination. Veterinarians may wish to make cat owners aware of the potential threats to human and wildlife health posed by cats permitted to defecate outdoors.

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in Journal of the American Veterinary Medical Association