1996 Rabies Annual Summary
Rabies Laboratory - Home
General Information:
- Current Rabies Data
- Annual Summary Reports
- History of Rabies in NY
- Raccoon Rabies
- Bat Rabies
- Virus Images
Accessing Lab Services:
- Info for Professionals
- Submission Policy
- Shipping Instructions
- Livestock Submissions
- Ante-Mortem Testing
Contact Us
Director, Rabies Laboratory
Richard Raczkowski:
Asst. Director, Rabies Laboratory
518-869-4527
Please contact us (518-869-4527) for data tables and image maps in an alternate format.
- Introduction
- Testing Results
- Raccoon Rabies
- Rabies in Domestic Animals--Human Health Implications
- Human/Bat Encounters
- Wildlife Vaccination Studies
- Other Testing Conducted
- 1996 Rabies Incidence Map (GIF 18k)
- 1996 Bat Rabies Map (GIF 96k)
- 1996 Terrestrial Rabies Map (GIF 26k)
Introduction
With 1084 laboratory-confirmed cases in the State during 1996, New York secured, for the sixth consecutive year, the dubious distinction of being the state with the greatest number of rabid animals. While the vast majority of cases were attributable to the raccoon rabies outbreak, the continued emergence of bat rabies as a source of human rabies cases nationally caused heightened awareness and a dramatic increase in submissions of bats during the year.
Two cases of rabies in domestic animals that caused massive epidemiologic investigations served as vivid reminders of the potential public health implications of spillover of wildlife rabies into domesticated species.
Testing Results
There were 9,876 animals examined for rabies in the State in 1996: 8,979 at the Wadsworth Center, 896 at the New York City Health Department, and 1 at a Department of Army laboratory.
Once again, cats were the animal most often submitted for rabies testing, with 2390 examined. There were 2353 bats examined, and 2033 raccoons. Among all animals examined at the Wadsworth Center, 26% (2356) bit a human, 28% (2522) had other non-bite human contact, 19% (1748) had reported contact with a dog, 15% (1340) had contact with a cat, and 23% (2103) were strictly surveillance specimens with no reported contacts. Among all domestic animals examined, 89% had potentially exposed one or more humans.
Rabies infection was confirmed in 1080 animals examined at the Wadsworth Center, 3 examined at the New York City laboratory, and one raccoon captured at Ft. Drum and examined at the Army's Ft. Sam Houston laboratory.
Wild species accounted for 62% of all examinations, and 96% (1039) of rabies cases. Rabid wildlife included 688 raccoons, 229 skunks, 74 bats, 23 grey foxes, 13 red foxes, 10 woodchucks, 1 coyote and 1 deer. There were 45 rabid domestic animals, including 28 cats, 9 cattle, 4 dogs, 2 horses, 1 goat, and 1 rabbit. Domestic animals accounted for 37% (3679) of all submissions but just 4% of all rabid animals. Among rabid domestic animals 80% (36) had reportedly exposed one or more humans: one rabid goat resulted in nearly 400 human exposures.
Raccoon Rabies
The raccoon rabies outbreak continued in a predictable pattern characterized by: a spread from existing areas into adjacent, previously unaffected areas (24 newly affected towns in 1996); an intense area with high incidence at the epizootic front (e.g., 76 cases in Jefferson County, 55 cases in Lewis County); a dramatic decrease in incidence to an enzootic level 1.5 - 2 years after initial introduction (e.g., Oswego County down from 73 cases in 1995 to 10 in 1996, Erie County down from 42 to 8 cases); and, a resurgence of cases after two to three years of enzootic rabies (Delaware County up from 1 case in 1995 to 14 in 1996, Greene County up from 4 to 26, and Albany County up from 32 to 93). Of all raccoons tested, 33% (688) were rabid, and among 45 raccoons that had bit a human 33% (15) were positive for rabies. However, 66% (390) of the 590 raccoons that had fought with a dog were rabid.
Rabid Domestic Animals/Human Interaction
Two 1996 rabies cases in domesticated species necessitated major public health investigations. A cat that had been at large at a campground in Orange County was determined to be infected with rabies on June 18. The effort to locate campers at potential risk required tracking camp registrants into 500 other campsites in the U.S., Canada and Mexico and to home addresses in twenty states and six other countries.
A goat from Tioga County tested positive for rabies on August 19. During the period it may have been infectious it had been displayed at a county fair visited by 25,000 people. More than 2,700 people were evaluated for exposure to the goat, as it had been walked on a leash in the fairgrounds and spent time at a petting zoo. Nearly 400 people received rabies treatment due to this one case, and the cost of the incident was estimated at $500,000.
Human Rabies Deaths--Bats
There have now been 22 human rabies deaths in the United States since 1990, of which 5 were acquired abroad. Of the 17 indigenously acquired cases, 15 have been associated with bat rabies, and only one resulted from a reported bite exposure. Two of the 15 cases occurred in New York State (1993 and 1995) following bat encounters in the home, with no recognized bite or known contact in either case.
These data encouraged the New York State Department of Health to follow the lead of the Centers for Disease Control and Prevention, and broaden its definition of bat encounters that require rabies examination of the bat and human postexposure treatment when the bat proves rabid or cannot be examined. This new policy resulted in a dramatic increase in the number of bats received for examination: 2353 bats were tested during 1996, a number 83% greater than the average for the previous five-year period (1288).
There were 74 rabid bats confirmed in the State in 1996, which is 28% greater than the average for the previous five year period (58). Otherwise, the distribution of bat rabies was not unlike previous years. It was widespread geographically, with the cases occurring in 66 different towns in 24 counties. The disease was also widespread among the indigenous bat species, with rabies confirmed in 64 big brown bats, 4 little brown bats, 2 hoary bats, 1 Keen's bat, 1 pipistrelle, 1 silver-haired bat, and 1 bat unidentifiable to species. Characteristically, big brown bats accounted for most (81%) of the cases.
Among the bats received at the Wadsworth Center for testing (2320), 5% (119) had bitten a human, 24% (552) had other non-bite human contact, 9% (207) contact with a dog, 35% (809) contact with a cat, and 35% (823) no reported contacts. Among the 74 rabid bats 9% (7) bit a human, 19% (14) had other non-bite human contact, 15% (11) contact with a dog, 37% (27) contact with a cat and 30% (22) no reported contacts. Among big brown bats 4.4% (64 of 1461) were rabid, while among little brown bats 0.6% (4 of 646) were rabid.
Overall, the rabies-positivity rate in tested bats was 3.1%, significantly lower than the average for the previous five-year period (4.4%). This is at least in part the result of a greater number of normally behaving bats being submitted because of the newly defined criteria for testing bats.
Wildlife Vaccination Trials
Trials to evaluate the efficacy of the distribution of baits containing vaccine for oral rabies vaccination of wildlife continued in several areas of the State, with programs in Albany, Rensselaer, and Essex Counties conducted by the Department of Health. Programs in Jefferson, Lewis, Niagara, Erie and Chautaugua Counties were conducted by the Diagnostic Laboratory of the New York State College of Veterinary Medicine at Cornell. The trials are designed to evaluate the effectiveness of the method to establish a barrier to spread of the disease into new areas, as well as its potential use to eliminate rabies in affected raccoon populations.
Other Tests Conducted
The demand for serologic testing of human sera to determine the need for rabies vaccination booster injections increased significantly again in 1996. The Wadsworth Center rabies laboratory received 1,623 samples during the period, 50% greater than the annual average for the previous five-year period. The laboratory also performed serologic tests for antibody in 281 animal sera in support of the oral rabies wildlife vaccination trials.
The Wadsworth Center performed 138 monoclonal antibody panel analyses to determine the causative variant of rabies virus associated with selected cases: all cases examined in terrestrial mammals occurring in New York in 1996 were identified as the raccoon rabies variant, and all bats evaluated were infected with one of four common bat rabies variants previously identified in the State.
(New York City data provided by Dr. Igbal Poshni, Director, Virus Laboratory, New York City Department of Health)