Gary A Balsamo, DVM, MPH&TM State Public Health Veterinarian Raoult C. Ratard, DVM, MPH&TM

1. The Epidemiology Of Rabies And Its Practical Application To Pre- And Post-Exposure Prophylaxis, Louisiana, 1988-2007 Gary A Balsamo, DVM, MPH&TM State Public Health Veterinarian Raoult C. Ratard, DVM, MPH&TM State Epidemiologist

2. Background • Incidence of rabies : approximately 3 cases per year in the U.S. • Integrated management • Animal Control • Vaccination Programs • Rabies remains enzootic in the U.S. and in Louisiana • Primary species (over 92% of cases): • Wildlife species • Bats • No human cases in LA. since 1953

3. Questions? Recommendations for Pre –Exposure Prophylaxis in veterinarians, wildlife workers, taxidermists in the state? Should recommendations for bite cases (Post –Exposure Prophylaxis) be uniform throughout the state?

4. Rabies, Louisiana 1988-2007

5. Materials and Methods • Risk based on the proportion of positive to negative animals tests (OPH and LSU laboratories) that identified rabies in groups and species of animals. • Species: dog, cat, exotic, cattle, horses, skunks, raccoons, bats, etc. • Groups: pets, wild terrestrial animals, agricultural animals (horses and domestic food animals), bats • Examined differences in risk by area of the state • Examined differences in risk by time of year

6. Rabies in LA., 1988-2007 • Bats: 84/871 (9.64%) positive • Pets: 14/16,651 (0.08%) positive • Wild terrestrial (skunks and raccoons primarily): 211/2100 (10.05%) positive • Agricultural Animals (ruminants and horses): 7/390 (1.79%) • Non-vector species (rodents, lagomorphs): 0/1245 (0.00%) • Non-native exotics: 0/10 (0.00%)

7. Does this risk differ by area of the state? • Geographic analysis…2 modes: • Split the state into terrestrial rabies endemic and terrestrial rabies non-endemic regions • Compare proportions (chi square analysis) • Analyze by public health region (9 regions) • Compare proportions (chi square analysis after grouping regions according to similar risk)

8. Public Health Regions and Terrestrial and Non-Terrestrial Rabies Endemic Areas

9. Results of terrestrial endemic to to non-endemic comparison: • Foxes and raccoons had been identified positive from the non-endemic areas…incorrectly identified as to location or were transported • No difference in agricultural animals, but very few tests performed

10. Results of public health region comparison: • Bats: Regions 3,6,8… a test on a bat was 4 times more likely to be positive than in other regions. OR: 4.0 (2.4-6.7)

11. Results of public health region comparison: • Skunks and wild terrestrials in general: Regions 4, 6, 7, and 8… a test on these animals was almost 24 times more likely to be positive than in other regions. [wild terrestrial: OR: 23.8 (10.5-54.0)][skunks: OR: 23.8 (5.7-99.8)]

12. Results of public health region comparison: • There was a significant difference in proportion of cats testing positive from regions 6 and 8 than from other areas of the state; however, the proportion in all areas was extremely small - regions 6 and 8: 0.55%, others: 0.04%

13. Results of temporal comparisons (Bats): Proportion of positive tests by region and month of the year • Regions were grouped by similarity of temporal pattern. • All regions (blue and red) exhibited an increase proportion of positive tests from late summer to early winter. • Regions 4,6,7 and 8 (all of north and central LA. & south central LA.) showed an additional spike in late spring.

14. Bat temporal conclusions: • Raw numbers of positive bats increase from very low numbers in January to a peak in September • Seen also in Texas (Sep), Alabama (Aug, Sep, Nov), USA (Aug) • Return of overwintering bats • Parturition in May and June • Increased proportion of positive bats identified in September (regions 1,2,3,5,9), and October (regions 4,6,7,8) • Seen also in Minnesota (Sep) • Increased bat to bat contact in late spring and early summer • Spring increase in proportion positive in regions 4,6,7,8 • Requires further study

15. Results of temporal comparisons (Skunks): Proportion of positive tests by region and month of the year • Region 4, (south central LA) showed the highest number and proportion of positive tests from January through March, however proportions of positive tests remained high throughout the year. • Regions 4,6,7 and 8 showed an increased proportion of positive tests January through June

16. Skunk temporal conclusions: • Winter and spring peak in regions 6,7,8 • Fall dispersal of juveniles and increased contact while denning and breeding • Persistent high proportion of positives observed in region 4 • Observed in other areas of the country • May be associated with areas of higher skunk density

17. Discussion • The Advisory Committee on Immunization Practices (ACIP): Pre-exposure rabies prophylaxis • Continuous • Vaccine production • Research labs • Serum titers every 6 months after initial series • Frequent (dx lab, spelunkers, animal control, wildlife rehab, taxidermists , vets in areas enzootic for rabies) • Serum titers every 2 years after initial series • Infrequent (Vets, vet students, wildlife rehab, taxidermists, animal control where rabies is uncommon) • Serum titers unnecessary

18. What do we recommend? • contact with terrestrial wildlife (esp. skunks) in regions 4,6,7,8 • Frequent • contact with terrestrial wildlife (unless rare contact) in region 5…absence of natural barriers • Frequent • contact terrestrial with wildlife in regions 1,2,3,9 • Infrequent • contact with only pet species anywhere in the state • Infrequent

19. What do we recommend? • contact with large animals (domestic ruminants or horses) in regions 4,5,6,7,8 • Frequent • Other studies: cattle rabies directly linked with presence of skunk rabies • This study: a positive test in a horse or domestic ruminant > 20 times more likely than in pet species (OR: 21.5 (8.6-53.5) • contact with large animals in regions 1,2,3,9 • Infrequent • contact with bats in all areas of the state • Frequent

20. Important • Anyone potentially exposed to a rabid animal that has been previously vaccinated for rabies (completed entire pre-exposure prophylaxis regimen), whether no titer, adequate titer, or inadequate titer that has been boosted or not, requires two booster vaccines. • another reason why veterinarians DO NOT always require titers.

21. Recommendations (continued) • Physicians and PH practitioners should reference this study in determining Post-exposure prophylaxis. • Encourage 10-day observation periods for pet species • Booster vaccines are recommended for pets after exposure to wildlife (test wildlife if available) • PEP: evaluate each case individually

22. Recommendations (continued) • Victims of bites from reservoir species (anywhere in the state)…PEP indicated if animal not available for testing • Unprovoked bites from pets in endemic areas • 10 day observation or testing • Consider: vaccination status, husbandry conditions, separation from wildlife, health status of pet • Provoked bites in endemic areas • 10-day observation or testing • Address with suspicion (change in nature of animal in addition to above) • Unprovoked bites and provoked bites in non-endemic areas • Considerations the same, but less likely to recommend PEP.

23. Recommendation: • In Louisiana public health personnel do NOT determine who receives PEP. • We inform physicians and victims as to the epidemiology of the disease. • We provide information on risk. • We strongly recommend the vaccines when circumstances require • but…the final decision rests with the physician and patient.

24. Are there changes in risk by season? • SEASONAL DIFFERENCES SHOULD NOT BE USED IN CONSIDERATION OF THE NEED FOR PROPHYLAXIS!!!

25. Acknowledgments: Environmental Services, Office of Public Health (OPH), Louisiana Department of Health and Hospitals (DHH) State Laboratory, OPH, DHH Louisiana Animal Disease Diagnostic Laboratory, Louisiana State University School of Veterinary Medicine

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