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.r-project.org/ . g. Madigan J, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, Calif: Personal communication, 2011. References 1. Foley J Biberstein E . Anaplasmataceae . In: Hirsh DC

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of the developed world . Epidemiol Rev 1996 ; 18 : 29 – 51 . 10.1093/oxfordjournals.epirev.a017914 2. Rangel JM Sparling PH Crowe C , et al. Epidemiology of Escherichia coli O157:H7 outbreaks, United States, 1982-2002 . Emerg Infect

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in American Journal of Veterinary Research

, et al. Descriptive epidemiology of bovine tuberculosis in Michigan (1975–2010); lessons learned [published online ahead of print Apr 20, 2011] . Vet Med Int 2011 ; doi: 10.4061/2011/874924. 3 Thoen CO Lobue PA Enarson DA , et al

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in American Journal of Veterinary Research

survival of M bovis. Acknowledgments Supported in part by the Michigan Department of Agriculture and Rural Development and the Diagnostic Center for Population and Animal Health and the Center for Comparative Epidemiology, Michigan State

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Observational Studies in Epidemiology was used to ensure thoroughness of the reporting. 26 Feedlot data Data were compiled from 2015 to 2018 for a large commercial cattle feeding operation (with approx 150,000 to 250,000 purchased head of cattle/y) based

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, Applied Biosystems, Grand Island, NY. g. Promega, Madison, Wis. h. Real-time PCR Research and Diagnostics Core Facility, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, Calif

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Abstract

Objective—To determine whether sequelae of infection differed among single versus double infection with Anaplasma phagocytophilum or Anaplasma marginale, with and without tick salivary extract, in cattle.

Animals—Eighteen 13-month old steers.

Procedures—Treatment groups of 3 cattle each included A marginale inoculated ID followed on day 35 by A phagocytophilum without tick saliva, A phagocytophilum followed on day 10 by A marginale without tick saliva, A marginale followed on day 35 by A phagocytophilum with tick saliva, A phagocytophilum followed on day 10 by A marginale with tick saliva, tissue culture control injection, and tick saliva control injection. Infection was monitored via clinical observations, CBC, serologic testing, and PCR analysis of blood and tissues.

Results—Infected cattle had significantly reduced weight gain. Anemia occurred 25 to 32 days after A marginale infection, which was attenuated by tick saliva. Parasitism was greater if cattle had not previously been inoculated with A phagocytophilum. Nine of the 12 treated cattle had positive results of PCR analysis for A phagocytophilum from at least 1 blood sample. Five tissue samples had positive results of PCR analysis for A phagocytophilum; PCR results for A marginale were positive in spleen, lung, lymph node, heart, and ear skin of infected cattle.

Conclusions and Clinical Relevance—Results indicated an important biological interaction between A marginale and A phagocytophilum infection as well as with tick saliva in disease kinetics and severity in cattle, which may be important for interpretation of diagnostic tests and management of disease in areas where both pathogens occur.

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in American Journal of Veterinary Research

Abstract

Objective—To evaluate clinical, microbiologic, and pathologic outcomes in mice after inoculation with 4 equine-origin Corynebacterium pseudotuberculosis strains.

Animals—15 C3H/HeJ mice.

Procedures—In a preliminary study, the optimum route of inoculation was determined. In the main study, mice were allocated to 4 treatment groups (3 mice/group). One slow- or rapid-growing equine-origin C pseudotuberculosis strain was inoculated ID into the mice of each treatment group.

Results—All 4 strains had distinct tropism for the liver. Histologic lesions associated with rapid-growing strains included focally extensive unencapsulated areas of acute, massive coagulative necrosis of hepatocytes with intralesional colonies of bacteria and variable portal hepatitis characterized by accumulations of mononuclear and polymorphonuclear inflammatory cells. In contrast, the livers of mice inoculated with slow-growing strains had multiple discrete, randomly distributed foci of hepatocellular necrosis and neutrophilic hepatitis that were considerably less severe than the lesions in the mice inoculated with the rapid-growing strains. Significantly more bacterial colonies were recovered from the organs of mice inoculated with rapid-growing than with slow-growing strains of bacteria. Bacteria were isolated from the liver, spleen, lungs, and mesenteric lymph nodes of mice inoculated with rapid-growing strains and from the liver and lymph nodes of mice inoculated with slow-growing strains.

Conclusions and Clinical Relevance—Study of host-bacteria interactions in hosts that are naturally infected with C pseudotuberculosis is difficult because of underlying genetic variability among animals, expense, and requirements for multiple replicates and control animals. The C3H/HeJ mice may provide a useful means for studying virulence mechanisms of C pseudotuberculosis.

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in the epidemiology of VS in endemic regions. Furthermore, these results may have an impact on the design of VS control strategies. Control of VS epidemics in the United States and Mexico is based on the quarantine of infected cattle and premises

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during the pasture period]). Descriptive epidemiology —Six blood collections were performed for each herd during the study. For each sample collection, seroprevalence was estimated as the ratio of the number of gE-seropositive cattle to the number of

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in American Journal of Veterinary Research