Recipient Organization
TUFTS UNIVERSITY
200 WESTBORO ROAD
N. GRAFTON,MA 01536
Performing Department
ENVIRONMENTAL & POPULATION HEALTH
Non Technical Summary
Tufts Cummings School of Veterinary Medicine has been operating a vaccination program for preventing the spread of raccoon rabies in free-ranging raccoons, one of the first wildlife rabies vaccination efforts in the United States. For 10 years, from the first vaccine distribution in 1994 to 2004, TCSVM and our cooperating partners were successful in keeping raccoon rabies off Cape Cod despite years of epizootic challenge. This program also succeeded in achieving one of the highest vaccination rates in a raccoon population reported by any vaccine program in the country. However, in early 2004, the first rabies case was detected on Cape Cod. The purpose of the study is to generate skunk field data in specified areas of Massachusetts following oral rabies vaccine distribution. The results of the serological analysis will allow the project collaborators to plan future vaccine distributions to maximize the effectiveness of the Oral Rabies Vaccination Program. Our challenge
is try to reduce and then eradicate rabies from Cape Cod, and re-establish the barrier.
Animal Health Component
75%
Research Effort Categories
Basic
25%
Applied
75%
Developmental
(N/A)
Goals / Objectives
Raccoon rabies was first detected in Massachusetts in 1992, and the pattern of distribution in wildlife was similar to other states with rabies positive raccoons far outnumbering rabies cases in other species of wildlife. However, beginning in 1997, the numbers of rabies positive skunks detected throughout Massachusetts surpassed the number of positive raccoons. Transmission of rabies by infected skunks is a potential threat to the integrity of the vaccine barriers since the vaccine is less effective in skunks, and may be the weak link to barrier breaches. In early 2004, the first rabies case was detected on Cape Cod. Since then, nearly 300 cases of rabies have been detected in wildlife on Cape Cod despite several attempts to halt the spread by vaccination. Rabies case distribution in wildlife has returned to the pre-1997 levels where raccoons far outnumber skunks cases. Our challenge now is try to reduce and then eradicate rabies from Cape Cod, and re-establish the
barrier. To reach our goal of rabies eradication we need to measure the effectiveness of the vaccine applications made so far by assessing vaccination rates in both raccoons and skunks on Cape Cod, in the two treatment areas. Currently we are using the two bait formats, block and sachet, in two separate areas within the vaccination zone on Cape Cod. Some sachets are dispensed by air over the few undeveloped area in both treatments areas, thus there is a mixed strategy, one predominantly block, the other sachet. For this project we propose to collect serum from live-trapped raccoons and skunks in the two treatment areas on Cape Cod during the summer of 2006 with the aid of veterinary students as research assistants. Additionally, we plan to work with several Cape Cod wildlife rehabilitators and animal control officers to collect serum samples from live animals brought in for treatment or euthanasia for rabies testing. We plan also to opportunistically collect serum from skunks and
raccoons submitted to the Wildlife Clinic at Tufts for determining background rates (if any) of rabies titers in these species from a non-vaccinated area in central Massachusetts. 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. These data will be analyzed in order to assess: 1. the overall vaccination rates in the skunks and raccoons 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 4. an assessment of presence of rabies titers in skunks and raccoons in an unvaccinated area
Project Methods
Rabies vector species are be trapped in box traps beginning at least 3 weeks after vaccinate application to allow for development of vaccination titers. Trapped wildlife is anesthetized with an IM injection of Ketamine/xylazine. Anesthetized animals have a blood sample taken, will be given a general health exam, weight, sex, and approximate age are recorded. A tag with a unique number is placed in each ear, and the animal is 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 treatment areas. For each area fifty traps are placed throughout a 1 square mile grid in good raccoon habitat. The traps (checked daily) are 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 allows for the calculation of population density estimates, thus maximizing the information gained from the trapping effort. Blood
samples are analyzed by the Centers for Disease Control and Prevention for rabies antibody developed in response to vaccination. Secondly, we test sick or injured rabies vector species for rabies virus infection. Sick, injured, or dead raccoons are collected by town animal control, and are submitted for rabies virus testing at the Massachusetts Department of Health Laboratory. We plan to have the research assistant work with local animal control to collect additional samples from these animals, such as teeth (analyzed for tetracycline, a biomarker put in the vaccine). Serum samples are sent to the CDC for titer analysis. Once the rabies titer data is available, we calculate vaccination rates within each baiting method area, and compare rates between areas. Further analysis will be made to determine whether there are differences in vaccination rates between sex or age class of the animals. Teeth will be analyzed for presence of the tetracycline biomarker depending on funding
availability. Population range estimates will be calculated using a modified Peterson method.