Recipient Organization
CLEMSON UNIVERSITY
(N/A)
CLEMSON,SC 29634
Performing Department
LIVESTOCK-POULTRY HEALTH
Non Technical Summary
Leptospirosis is a disease of zoonotic potential and is thus important from a public health standpoint. It is a reportable disease in people. Humans are susceptible to all of the pathogenic serovars that are found in domestic animals, and are considered an incidental host. In addition to indirect transmission through contaminated water or soil, people may also become infected by direct contact with urine or tissues from infected animals. The disease in people is often associated with occupation, which allows for direct exposure to infected animals, or recreational activities that allow for exposure to contaminated water and soil. Since dogs can have more direct contact with people than do livestock species and wildlife, dogs can be an important potential source of infection in people. The disease in people can vary from subclinical to severe and can potentially result in death from meningitis, renal failure or hepatic failure. Accurate, rapid diagnostic testing
capabilities to detect the disease in animals are thus warranted to help eliminate human exposure as much as possible. In addition, such testing will allow for more rapid implementation of appropriate treatment for affected dogs and potentially exposed people. In addition to the zoonotic potential that exists between dogs and people, infected dogs could also potentially serve as a source of infection to other domestic animals, such as livestock species. If a dog becomes infected with a serovar that is potentially pathogenic to other domestic animals, the dog may develop persistent infection in the kidneys. The result is a carrier state in which the organisms may be shed in the urine for ≥1 year. The shed organisms serve are a source of infection for other animals. Impacts: The information obtained from this project is intended to provide a better perspective of the incidence of leptospirosis in pet dogs in South Carolina, which has not been previously reported. Investigation and
implementation of more sophisticated diagnostic techniques within the CVDC laboratory will lead to more rapid, accurate diagnosis which could have direct impact on animal and human health.
Animal Health Component
45%
Research Effort Categories
Basic
20%
Applied
45%
Developmental
35%
Goals / Objectives
1) To investigate the incidence of leptospirosis in the pet dog population in South Carolina. This will be a retrospective and prospective investigation over the time period of 2002-2012. This information will be based on laboratory submissions to the CVDC. 2) To implement a Polymerase Chain Reaction (PCR) assay for detection of leptospirosis at the Clemson Veterinary Diagnostic Center (CVDC). 3) To compare the PCR method to currently utilized diagnostic techniques. 4) To obtain epidemiologic information on reported human leptospirosis cases in uth Carolina over the same time period, and to investigate a possible correlation with pet dog infection.
Project Methods
The retrospective portion of this study will involve searching the VETLIMS database to determine how many samples from dogs were submitted to CVDC for leptospirosis testing since 2002, and how many of these samples fit the criteria for being positive or suspect positive based on the testing performed at CVDC. These samples may include urine submitted for dark field microscopy, serum submitted for microagglutination (MAT) testing, kidney and/or liver submitted for histopathology with silver stain, and in-house or field necropsies in which any of these tests were requested and performed. Information obtained from this search would be summarized into a table indicating the accession number, tests performed and results of the tests. In addition, dog breed, age, sex, vaccination status, type/brand of vaccination, and location (county) will be included if such information was/is provided by the submitting veterinarian. The gathering of information from the VETLIMS database
will be facilitated by Mike Martin, DVM, MPH, Veterinary Informatics Specialist, Clemson University, Livestock Poultry Health, Animal Health Programs. Samples from dogs are continuously being submitted to CVDC for leptospirosis testing, and test results will continuously be assessed. In addition to the tests currently available at CVDC and the implementation of PCR testing, other diagnostic methods can be explored, tested and compared to the current methods using these submitted samples as new methods become available. When possible, serum, urine and fresh tissues may be frozen and stored until new test methods are available for use within the laboratory. Formalin fixed, processed tissues are maintained in paraffin embedded blocks for a minimum of 7 years, and can be used for special staining or potentially, immunohistochemistry, should this become commercially available. For this study, all of the diagnostic testing on dogs will be performed at CVDC. A positive leptospirosis test
will be defined as a MAT titer of ≥800 in a single serum sample, a fourfold increase in MAT titers in paired serum samples (samples submitted from the same animal approximately 2 weeks apart), detection of spirochetes in urine samples with dark field microscopy, and/or histopathologic lesions compatible with leptospirosis with detection of Leptospira-like organisms using silver stain in liver or kidney. A MAT titer of ≥800 will be used because titers this high are considered unlikely with vaccination. A positive PCR test will be defined as a positive leptospirosis infection after validation of the test is complete. PCR validation and testing will be supervised by Adam Leaphart, PhD, Microbiologist, Clemson Veterinary Diagnostic Center. Information on reported human leptospirosis infections during the same time period will be obtained through collaborative efforts with personnel at DHEC, and a possible correlation with a pet dog infection will be investigated when possible.
Information on the test method(s) used to determine positive infection in humans will be gathered when possible.