Gary A Balsamo, DVM, MPH&TMState Public Health Veterinarian

Raoult C. Ratard, DVM, MPH&TMState Epidemiologist

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

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?

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

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%)

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)

Species or Group

Endemic Non-endemic

OR (95% CI) or p value

Bats 13.3% 4.7% 3.1 (1.7-5.5)

SkunksSkunks 48.0%48.0% 0.0%0.0% p < 0.0001p < 0.0001

Wild terrestrials

15.3% 0.6% 30.1 (11.2-81.4)

PetsPets 0.1%0.1% 0.0%0.0% p = 0.0144p = 0.0144

•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

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)

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)]

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%

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.

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

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

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

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

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

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

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.

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

• 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.

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.

SEASONAL DIFFERENCES SHOULD NOT BE USED IN CONSIDERATION OF THE NEED FOR PROPHYLAXIS!!!

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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