Progress 10/01/00 to 09/30/05
Outputs
Fecal samples were collected from 724 horses admitted to a veterinary teaching hospital. The estimated prevalence (95% confidence interval) of Salmonella shedding on admission and during hospitalization was 0.5% (0.1, 2.0) and 4.3% (2.2, 8.1), respectively. The highest incidence occurred during June, but no significant (P>0.5) temporal clusters of horses shedding Salmonella were detected. Overall, presenting complaint (for example, lower respiratory tract disease) was the most-important indicator of Salmonella culture positive status. Thirty-seven horses (suspected salmonellosis cases) and their stalls were sampled. Nine (26%) horses were cultured positive for Salmonella, and 23 (68%) were positive by Salmonella PCR on at least one occasion. Twenty-one stalls were sampled and Salmonella was cultured from at least one stall site on 6 (8%) of 78 occasions. At least one stall site was positive by Salmonella PCR on 69 (90%) of 77 occasions. The highest proportions of PCR
positive samples originated from drains (68%) and cracks and corners (52%). Salmonella was cultured from 3 stalls following both initial and second cleaning and disinfection cycles, but was culture negative following use of a peroxygen disinfectant. All culture positive stalls were PCR positive. A randomized, double-blinded, clinical trial was conducted to estimate the incidence of Salmonella fecal shedding in hospitalized horses administered a probiotic versus a placebo. One hundred and thirty horses admitted with non-gastrointestinal disease to a veterinary teaching hospital were orally administered either the probiotic or placebo on 4 occasions. Administration of the probiotic reduced the incidence of Salmonella shedding after 48 hours of hospitalization by approximately 65% (relative risk 0.35; 95% CI, 0.07 to 1.68). Hospitalized horses shed Salmonella in their feces at a low rate, and sporadically, probably reflecting the prevalence of inapparent Salmonella infection in the
source population. To detect environmental sources of Salmonella, samples from stall drains and cracks and corners of stalls should be collected following two cycles of cleaning and disinfection and cultured for Salmonella. Stalls that have previously housed horses with suspected salmonellosis should only be used to accommodate newly hospitalized patients following negative culture results from these stalls. Dosing horses with probiotics as early as possible prior to anticipated stressful events (for example, transportation, surgery, antibiotic treatment), followed by several subsequent treatments may reduce contamination of the hospital environment by Salmonella and the risk of salmonellosis outbreaks.
Impacts
Information on baseline prevalence of Salmonella shedding by horses admitted to the teaching hospital, risk factors for equine salmonellosis, sites of environmental contamination with Salmonella, and prevention of salmonellosis by probiotic administration allows control programs to prevent, and to minimize the impact of, outbreaks of salmonellosis in teaching hospitals to be developed.
Publications
- Alinovi, C.A., Ward, M.P., Couetil, L.L, Wu, C.C. Risk factors for fecal shedding of Salmonella from horses in a veterinary teaching hospital. Preventive Veterinary Medicine 2003, 60: 307-317
- Alinovi, C.A., Ward, M.P., Couetil, L.L, Wu, C.C. Detection and removal of Salmonella contamination in a veterinary teaching hospital. Journal of the American Veterinary Association 2003, 223: 1640-1644
- Ward, M.P., Alinovi, C.A., Couetil, L.L, Wu, C.C. Fecal shedding of Salmonella in horses admitted to a veterinary teaching hospital. Journal of Equine Veterinary Science 2003, 23:403-407
- Ward, M.P., Alinovi, C.A., Couetil, L.L, Glickman, L.T., Wu, C.C. A randomized clinical trial using probiotics to prevent Salmonella fecal shedding in hospitalized horses. Journal of Equine Veterinary Science 2004, 24: 242-247
- Ward, M.P., Alinovi, C.A., Couetil, L.L., Wu, C.C. Evaluation of a PCR to detect Salmonella in fecal samples of horses admitted to a veterinary teaching hospital. Journal of Veterinary Diagnostic Investigation 2005, in press
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Progress 10/01/02 to 09/30/03
Outputs
Identification of risk factors for horses shedding Salmonella in their faeces helps identify patients at-risk of infection and can protect the overall population through heightened biosecurity. Faecal samples from 230 hospitalized horses were cultured for Salmonella spp and tested with a polymerase chain reaction (PCR) Salmonella DNA. Historical data were collected on 21 putative risk factors and assessed for association with the risk of a horse being culture positive or PCR positive, using backwards stepwise logistic regression. Only presenting complaint (confounded by age, breed and gender) was significantly (P-value less than 0.05) associated with positive Salmonella culture results; housing, age and breed (confounded by gender) were significantly associated with positive PCR results. Analysis of residuals showed that the PCR model was not robust; the culture model was robust, but individual risk factor's estimates were changed by removal of outliers. Overall,
presenting complaint (for example, lower respiratory tract disease) was the most-important indicator of culture status.
Impacts
Risk factors for equine salmonellosis have been described in horse populations at numerous veterinary teaching hospitals. However, study populations have generally been restricted to patients with colic, diarrhoea, clinical salmonellosis or those with nosocomial infection during an outbreak. Results of the present study indicate that in non-outbreak situations, the overall health of admitted horses may be the most important factor for identifying horses that are shedding Salmonella at admission. This information may allow targeted testing of horses and patient isolation, to prevent contamination of the hospital environment. Because this study was conducted on the general hospitalized population, its results may be generalized to other hospitalized populations in which outbreaks of nosocomial salmonellosis are not occurring.
Publications
- Ward, M.P., Alinovi, C.A., Couetil, L.L, Wu, C.C. Fecal shedding of Salmonella in horses admitted to a veterinary teaching hospital. Journal of Veterinary Equine Science 2003;23:403-407.
- Alinovi, C.A., Ward, M.P., Couetil, L.L, Wu, C.C. Risk factors for fecal shedding of Salmonella from horses in a veterinary teaching hospital. Preventive Veterinary Medicine 2003;60:307-317.
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Progress 10/01/01 to 09/30/02
Outputs
Between October 2000 and June 2001 a survey of horses hospitalized or treated as outpatients at the Purdue University Veterinary Teaching Hospital was undertaken. Fecal samples were collected from horses and cultured for Salmonella spp. If a horse was hospitalized for 3 or more days, samples were collected on the day of admission, the day of discharge and at least once during hospitalization. The first fecal sample collected from each horse was also tested for the presence of Salmonella DNA using a polymerase chain reaction. Fecal samples were collected from 724 admitted and 232 hospitalized horses. Salmonella spp was isolated on 24 occasions from 12 horses, isolation being achieved most commonly (n=7) from the second fecal sample collected from each horse. S.newport (n=9) and S.typhimurium (n=4) were the most commonly isolated serotypes. The estimated prevalence (95% CI) of shedding on admission was 0.5% (0.1-2.0). Estimated incidence-density and cumulative-incidence
rates of shedding during hospitalization were 4.7 per 1000 horse-years at-risk (2.5-8.4) and 4.3% (2.2-8.1), respectively. The highest incidence occurred during June 2001, but no temporal clusters of horses shedding Salmonella spp were detected. Analysis of risk factors for Salmonella infection is currently being completed.
Impacts
The epidemiology of endemic Salmonella infection at the study site has been characterized. This has provided a baseline against which the effectiveness of surveillance and disease control programs against Salmonella infection in the hospital population can be measured.
Publications
- Ward MP, Alinovi CA, Couetil LL, Wu CC. Epidemiologic characteristics of fecal Salmonella shedding in a population of hospitalized horses. In RP Ellis (editor) Proceedings of the 83rd Annual Meeting of the Conference of Research Workers in Animal Diseases, St. Louis, 10-12 November 2002. Iowa State University Press, Ames IA.
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Progress 10/01/00 to 09/30/01
Outputs
Between October 2000 and June 2001 a survey of horses hospitalized or treated as outpatients at the Purdue University Veterinary Teaching Hospital was undertaken. Fecal samples were collected from horses and cultured for the Salmonella spp. If a horse was hospitalized for 3 or more days, samples were collected on the day of admission, the day of discharge and at least once during hospitalization. The first fecal sample collected from each horse was also tested for the presence of Salmonella DNA using a polymerase chain reaction. During the study period, 1044 patient admissions occurred; fecal samples were collected from 558 of these admissions, and 246 horses (44%) were sampled on at least 3 occasions. Environmental samples have also been collected from a total of 40 isolation stalls housing horses with suspected salmonellosis. Sample testing and identification of Salmonella spp. is being undertaken. Clinical records of all horses that were sampled on at least 3
occasions have been abstracted. History, presenting signs, diagnosis, therapy and procedures information has been compiled.
Impacts
Data collected will allow risk factors for salmonellosis in horse populations to be identified. Using this information, programs to better control and prevent outbreaks of salmonellosis will be designed.
Publications
- No publications reported this period
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