Recipient Organization
TUFTS UNIVERSITY
200 WESTBORO ROAD
N. GRAFTON,MA 01536
Performing Department
Infectious Disease and Global Health
Non Technical Summary
Tufts Cummings School of Veterinary Medicine (TCSVM) has been operating a vaccination program for preventing the spread of raccoon rabies since 1994. The program is run in cooperation with the Massachusetts Department of Public Health, Massachusetts Department of Fish and Game, USDA Wildlife Services, and the Center for Disease Control and Prevention. Raccoon strain rabies first entered Massachusetts in 1992 and spread rapidly across the state. In 1993 the Massachusetts legislature provided funds for TCSVM to create a barrier of vaccinated raccoons along the Cape Cod Canal to prevent the spread of rabies onto Cape Cod, one of the first wildlife rabies vaccination efforts in the United States. For 10 years we were successful in keeping raccoon rabies off Cape Cod. This program also succeeded in achieving one of the highest vaccination rates in a raccoon population in the country (60% of raccoons vaccinated in Massachusetts compared to less than 30% elsewhere).
Additionally, the program established vaccination strategies for suburban landscapes that have been used nationally. In 2004 the first rabies case was detected on Cape Cod. Since then, there have been over 250 cases of rabies detected in wildlife on Cape Cod despite several attempts to halt this spread by vaccination on the Cape itself. Our challenge now is to try to reduce and then eradicate rabies from Cape Cod, and re-establish the barrier. We can best reach our eradication goal by analyzing the efficacy of the current vaccination strategy through measurement of the vaccination rate in the raccoon population.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
(N/A)
Goals / Objectives
Cape Cod is a region of Massachusetts with diverse land use. Much of the landscape is rural, especially on the outer Cape, and livestock in the form of horses and small ruminants are commonly kept for small farm and backyard hobby use. Rabies is a disease with significant public health importance and the primary source of human exposure is domestic animals. Therefore control of rabies in wildlife is a vital step in protecting domestic animals and livestock from exposure to rabies, and thereby protecting the public health. An analysis of the success of the Oral Rabies Vaccine (ORV) program in achieving effective vaccination rates in raccoons and other native rabies vector species on Cape Cod is especially important at this time. After effectively preventing the spread of the rabies epizootic onto Cape Cod for over 10 years, the ORV program is currently facing new challenges due to a breach of the vaccine barrier in early 2004, and the subsequent rapid spread of rabies
into naive wildlife populations on the Cape. The ORV program will be able to use the vaccination rate information generated by this project to formulate vaccine distribution plans that have maximum effectiveness in reaching target wildlife and that make the best use of available resources. Adapting vaccination plans for future vaccine distributions based on the vaccination rate data generated by this project, and using information on the comparative effectiveness of two different baiting methods will enhance the overall success of the program in protecting livestock and human health by reducing the prevalence of rabies infections in the native wildlife on Cape Cod and eventually eliminating the disease and reinstituting the vaccine barrier. This project will produce rabies titer data for raccoons and other native rabies vector species sampled in two separate regions of the vaccine zone on Cape Cod, Massachusetts. These data will be analyzed in order to assess: 1. the overall
vaccination rates in the wildlife species throughout the vaccine zone; 2. the vaccination rates achieved in two areas where different baiting methods were used; 3. a comparison of the vaccination rates achieved by the two different baiting methods used. The results of the analysis will be available to the project coordinators and collaborators for use in planning for the next vaccine distribution in order to maximize the effectiveness of the ORV program.
Project Methods
Rabies vector species will be trapped in box traps within the different baiting method areas on Cape Cod. This will begin at least 3 weeks after the spring vaccine application to allow for development of titers in the vaccinated animals. Trapped wildlife will be anesthetized with an intramuscular injection of ketamine/xylazine. Anesthetized animals will have a blood sample taken, be given a general health exam, and have weight, sex, and approximate age recorded. A tag with a unique number will be placed in each ear, and the animal will be returned to the trap to recover from anesthesia, and then released at the site of capture. We plan two trapping periods, one in each of the two sample areas. For each sample area fifty traps will be placed throughout a 1 square mile grid in good raccoon habitat. The traps will be open for 4 nights, closed for 3, then opened for a final 4 nights, for a total of 400 trap nights in each area. This trapping strategy follows a
mark-recapture protocol that also allows for the calculation of population density estimates, thus maximizing the information gained from the trapping effort. Blood samples will be processed, and sera will be analyzed by the Centers for Disease Control and Prevention for rabies antibody developed in response to vaccination. Secondly, we will test sick or injured raccoons and other rabies vector species for rabies virus infection. Sick, injured, or dead raccoons (and other rabies vector species) will be collected by town animal control, and submitted for rabies virus testing to the Massachusetts Department of Public Health Laboratory. We plan to have the research assistant work with local animal control to collect additional samples from these specimens, such as teeth that can be analyzed for the biomarker tetracycline put in the bait, in order to assess uptake of baits. In cases where the sick animals are collected alive, the research assistant will be available to collect blood and
other samples prior to euthanasia, adding another valuable source of animals to the testing pool. Once the rabies titer data is available, we will calculate vaccination rates within each baiting method area, and compare rates between the different areas. Further analysis will determine whether there are differences in vaccination rates between sex or age class of the animals. Project preparation will begin in early June. Serum sample collection will begin approximately 4 weeks after the spring 2006 baiting season and will continue through July. This will provide information on vaccination rates in the target species, including the raccoon young-of-the-year. Serum samples will be processed and submitted for laboratory analysis and archiving, as they are collected. Titer results may not be available for up to 6 months after submission.