Human Rabies Postexposure Prophylaxis during a Rac Rabies Epizootic in New York, 1993 and 1994.

We describe the epidemiology of human rabies postexposure prophylaxis (PEP) [ILLEGIBLE TEXT] four upstate New York counties during the 1st and 2nd year of a raccoon rabies epizootic. We obtained data from records of 1,173 persons whose rabies PEP [ILLEGIBLE TEXT] reported to local health departments in 1993 and 1994. Mean annual PEP [ILLEGIBLE TEXT] rates were highest in rural counties, in summer, and in patients 10 to 14 and 35 to 44 years of age. PEP given after bites was primarily associated with unvaccinate dogs and cats, but most (70%) was not attributable to bites. Although pet vaccination and stray animal control, which target direct exposure, remain the cornerstones of human rabies prevention, the risk for rabies by the nonbite route (e.g., raccoon saliva on pet dogs' and cats' fur) should also be considered.

Raccoon rabies, present in the southeastern United States since the 1950s, [ILLEGIBLE TEXT] responsible for an epizootic in the U.S. mid-Atlantic region during the 1970s [ILLEGIBLE TEXT] raccoons were translocated there for hunting (1). The introduction of the variant virus associated with raccoons into a rabies-naive raccoon population caused the intensive animal rabies outbreak on record, in part because of the abundance of [ILLEGIBLE TEXT] in suburban environments throughout the mid-Atlantic and northeastern [ILLEGIBLE TEXT] areas. Raccoon rabies affects approximately one million square kilometers of the United States with a human population of approximately 90 million.

Since the mid-Atlantic raccoon rabies epizootic entered New York State in 1990, number of rabid animals increased from 54 in pre-epizootic 1989 to 2,746 (89% raccoons) in 1993--the largest number of rabid animals ever reported from any [ILLEGIBLE TEXT] Despite traditional public health measures for rabies control (e.g., pet [ILLEGIBLE TEXT] animal control, public education), human rabies postexposure prophylaxis (PEP) inevitably increased with the arrival of the epizootic front (3). Preliminary data [ILLEGIBLE TEXT] York documented a 4,000% increase in the absolute number of persons receiving from 81 (1989) to 3,336 (1993) (4). The epidemiologic trends of human PEP in York State remain largely undescribed.

One of the Healthy People 2000 objectives formulated by the U.S. Public Health is to reduce by 50% the need for human rabies PEP by the year 2000 (5). A [ILLEGIBLE TEXT] the number of PEP cases, which are not reportable, appears unattainable without defining the numerator, as well as the epidemiologic characteristics of [ILLEGIBLE TEXT] events leading to suspected rabies exposure and inappropriate treatments.

We describe demographic and animal exposure data associated with human [ILLEGIBLE TEXT] an area with epizootic raccoon rabies. The epidemiologic description is intended medical practitioners and public health officials in reducing the incidence of domestic animal exposure to rabid animals and thus in minimizing the need for P communities affected by the raccoon rabies epizootic.

The Study

Setting

Four contiguous upstate New York counties (Monroe, Wayne, Cayuga, and Ono were first affected by the raccoon rabies epizootic between December 1992 and [ILLEGIBLE TEXT] 1993 (Figure 1). Monroe and Onondaga Counties, encompassing the cities of [ILLEGIBLE TEXT] and Syracuse, are predominantly urban-suburban, with human population [ILLEGIBLE TEXT] per square kilometer and 230 per square kilometer, respectively. Wayne and [ILLEGIBLE TEXT] Counties are predominantly rural-suburban, with relatively lower population [ILLEGIBLE TEXT] 57 and 45 people per square kilometer, respectively. The four-county region in [ILLEGIBLE TEXT] upstate New York comprises 7,090 square kilometers and has an estimated [ILLEGIBLE TEXT] population of 1,354,377.

[Figure 1 ILLUSTRATION OMITTED]

Data Characteristics and Sources

We considered all human rabies PEP cases reported in 1993 and 1994 for the study area. The PEP capture rate was believed high because local health units were responsible for providing funds for any treatment expenses not covered by health insurance, and a completed, rabies report form was required before reimbursement of the local health unit from state funds.

The New York State Sanitary Code requires physicians to report potential human exposure to rabies and PEP administration to county health departments. We abstracted data from these standardized reports and patient records. Data were grouped by patient demographics, animal characteristics, and exposure details. Exposure source was defined as the suspected- or confirmed-rabid animal that directly or indirectly resulted in one or more potential human exposures to rabies. Direct contact exposure consisted of direct contact (e.g., bite, scratch) or contamination of mucous membranes with potentially mucous membranes with potentially infectious material from a rabid animal. Indirect contact consisted of contamination from a fomite (e.g., through racoon saliva on a pet's fur with a pet owner's open wounds or mucous membranes).

Analyses

Population figures from the 1990 New York State census were used to calculate the incidence of PEP by county, age, and gender (6). Descriptive analyses of data elements were made through queries of Microsoft Access relational database. Each PEP contributed to the denominator of the analyses. Since multiple PEP cases occurred from exposure to a single animal, data for individual animals were also summarized. Chi-square tests were performed with Epi-Info Version 5 software.

Findings

PEP Incidence

The annual PEP incidence for the study area increased from [is less than] 1 case per 100,000 in pre-epizootic 1992 to 35 cases in 1993 and 52 cases in 1994. Of 1,173 cases of rabies PEP in the study areas, 474 were reported in 1993 and 699 cases were rep 1994. The mean annual incidence of PEP was 32 cases per 100,000 for the urban (Monroe and Onondaga; 315 residents per square kilometer) and 123 cases per 1 for the two rural counties (Wayne and Cayuga; 51 residents per square kilometer

Season

The number of PEP cases peaked in summer to early autumn (Figure 2). During highest number of PEP cases occurred approximately 4 to 6 months (August thro November) after the invasion of raccoon rabies during March through June 1993 the highest number occurred in summer (June through August).

[Figure 2 ILLUSTRATION OMITTED]

Gender and Age

Gender and age data were available for 100% and 95% of all patients, [ILLEGIBLE TEXT] 1,173 PEP cases, 642 (55%) were administered to male and 531 (45%) to female The mean annual incidence of PEP in male and female patients was 47 and 38 [ILLEGIBLE TEXT] 100,000, respectively. The PEP rates were highest in persons 10 to 14 years of a per 100,000) and 35 to 44 years of age (113 per 100,000) (Figure 3). The median 29 and 31 years for male and female patients, respectively. No significant [ILLEGIBLE TEXT] was observed between gender and age groups for the study area.

[Figure 3 ILLUSTRATION OMITTED]

Exposure Source Species

Exposure to wild animals accounted for 783 (67%) of all PEP cases (Table 1). A wildlife, raccoons were by far the leading source of exposure, accounting for 589 of 779 PEP cases due to wildlife exposure. The other sources of wildlife [ILLEGIBLE TEXT] bats (54 cases), skunks (35 cases), foxes (28 cases), white-tailed deer (13 cases), woodchucks (12 cases), small rodents (9 cases), sika deer (4 cases), and other [ILLEGIBLE TEXT] species (39 cases). Of 390 domestic animal exposures resulting in PEP, 205 were attributed to cats, 165 to dogs, 12 to cattle, 5 to pet rabbits, and 3 to horses. [ILLEGIBLE TEXT] cases resulting from exposure to cats and dogs, 66% and 67%, respectively, were after contact with stray animals unavailable for the recommended 10-day confine and observation to role out rabies or euthanasia and testing. Dog exposures were disproportionately higher in urban (137 [18%] of 753) than in rural counties (28 420) (p [is less than] 0.001) (Table 2). In urban areas, dog exposure was primarily due to [ILLEGIBLE TEXT] unowned dogs (95 [69%] of 137). In rural areas, stray or unowned dogs [ILLEGIBLE TEXT] (39%) of 28 dog exposures (p [is less than] 0.01). Only one dog (in a rural county) tested [ILLEGIBLE TEXT] rabies in the study area in 1993 and 1994. Of 68 pet cats resulting in human expo (90%) were not vaccinated against rabies compared with 14 (24%) of 58 pet dog [is less than] 0.001).

Table 1. Human rabies postexposure prophylaxis (PEP), New York State, 1

                                    Nonbite (N=818)

                                      Direct(b)
                Bite
                (N=355)    Scratch   Saliva     NT    Blood
Animal source   N (%)      N (%)     N (%)    N (%)   N (%)

Raccoon          37 (10)   18 (33)       44       4      13
                                       (29)    (67)    (93)

Bat (all         29 (8)     3 (6)        12       1       0
species)                                (8)    (17)     (0)

Other wild       24 (7)     5 (11)       21       0       1
species                                (14)     (0)     (7)

All wild         90 (25)   26 (47)       77       5      14
species                                (51)    (84)    (100)

Cat             114 (32)   29 (53)       41       0       0
                                       (28)     (0)     (0)

Dog             151 (43)    0 (0)        13       0       0
                                        (9)     (0)     (0)

Other             0 (0)     0 (0)        19       1       0
domestic                               (13)    (17)     (0)
species

All domestic    265 (75)   29 (53)       73       1       0
species                                (49)    (17)     (0)

Total           355 (30)   55 (55)      150       6      14
                                       (13)    (0.5)    (1)

                Indirect(c)
                Saliva
Animal source   N (%)          to

Raccoon         472(d) (79)     5

Bat (all        9 (2)
species)

Other wild      89 (15)
species

All wild        570 (96)
species

Cat             21 (4)

Dog             1 (<1)

Other           0 (0)
domestic
species

All domestic    22 (4)
species

Total           592 (51)      1,1

(a) Data are from Cayuga, Monroe, Onondaga, and Wayne Counties.

(b) Direct contamination of an open wound or mucous membrane with potentially infectious mater saliva, nervous tissue (NT), or blood (mixed with other body fluids), from a rabies-suspect or [ILLEGIBLE TEXT] animal.

(c) No direct contact with a rabid or suspect-rabid animal. Indirect exposure through possible [ILLEGIBLE TEXT] saliva on an animal (i.e., pet dog or cat) or inanimate object resulting in contamination of an [ILLEGIBLE TEXT] or mucous membrane.

(d) p < 0.001. More people received PEP after indirect exposure to saliva from raccoons than from species (472 PEP cases due to indirect contact with 261 raccoons).

(e) Total PEP cases with raccoon as an exposure source (includes one case with no reported route exposure).

Table 2. Human rabies postexposure prophylaxis (PEP) in New York State, 1993-94: urban and rural settings(a)

                                          All four
                       Urban      Rural   counties
Animal source          N (%)      N (%)      N (%)

Dog(b)              137 (18)    28 (7)    165 (14)
Cat                 130 (17)    75 (18)   205 (17)
Other domestic
  species(c)          5 (<1)    15 (4)     20 (2)
All domestic
  species           272 (35)   118 (28)   390 (33)
Raccoon              41 (45)   248 (59)   589 (50)
Bat (all species)    41 (5)     13 (1)     54 (5)
Striped skunk        29 (4)      6 (<1)    35 (3)
Fox 19(3)             9 (2)     28 (2)
Other wild
  species(d)         51 (4)     26 (2)     77 (7)
All wild species    481 (65)   302 (72)   783 (67)
Total               753        420        1,173
Rate per
  100,000 pop.      32         123         43

(a) Characteristics of human rabies PEP cases reported to the health departments of the two relatively urbanized counties, Onondaga and Monroe, and the two relatively rural counties Cayuga and Wayne, during 1993 and 1994.

(b) p < 0.00. Human PEP rates due to dog exposures were significantly higher in urban counties.

(c) Other domestic species include 2 and 3 PEP cases due to cow and horse exposure in the urban counties and 10 and 5 cases due to cow and domestic rabbit exposure in the rural counties, respectively.

(d) Other wild species includes 17, 6, 4, 2, 2, and 1 PEP cases due to an unknown animal type, wild rodent (other than woodchuck), 4 Sika deer (exotic, captive species), opossum, coyote, and mink in the urban counties and 17 and 3 PEP cases due to an unknown animal type and wild rodent (other than woodchuck) in the rural counties, respectively.

Type of Exposure

Of 1,173 PEP cases, 35 resulted from animal bit 817 (70%) from nonbite encounters (Table 1). A exposure not reported in case involved a raccoon Suspected contact with saliva (148 cases from [ILLEGIBLE TEXT] contact and 594 from in contact) was [ILLEGIBLE TEXT] (91%) of 817 PEP cases nonbite exposure; [ILLEGIBLE TEXT] nervous tissue (6 PEP [ILLEGIBLE TEXT] blood (14 PEP cases) [ILLEGIBLE TEXT] for 2% of cases due to [ILLEGIBLE TEXT] exposure. Fifty-five (7 nonbite exposures were attributable to scratches cats (responsible for 29 cases), 16 raccoons (18 bats (3 cases), 2 wild [ILLEGIBLE TEXT] cases), and 3 other wild (3 cases). Of 355 bite [ILLEGIBLE TEXT] (3 cases). Of 355 bite [ILLEGIBLE TEXT] 265 (75%) involved do animals (151 due to 150 114 due to 108 cats); 90 involved bites from [ILLEGIBLE TEXT] animals--34 raccoons (responsible for 37 PEP 27 bats (29 cases), 9 [ILLEGIBLE TEXT] cases), and 13 other [ILLEGIBLE TEXT] (15 cases).

Mode of Contact

Of 1,173 cases, 594 (51 occurred because of [ILLEGIBLE TEXT] indirect contact with a [ILLEGIBLE TEXT] rabid animal; 583 (98%) occurred after suspected exposure to saliva from (or suspect rabid) animal on the fur of a nonsuspect dog, cat, or other animal. In these cases, PEP was administered after suspected exposure by possibly [ILLEGIBLE TEXT] fomites including door knobs, traps, arrows, a flashlight, and a wire. Possible [ILLEGIBLE TEXT] exposure to dogs with potentially infectious material on their fur resulted in 507 PEP cases, while suspected indirect exposure by cats resulted in 70 (12%) cases. suspected exposure sources were a horse, rabbit, pet duck, chicken, wild bird, [ILLEGIBLE TEXT] exotic sika deer, and a person.

Group Exposure

Exposure of one person to a suspect rabid animal precipitated 625 (53%) PEP [ILLEGIBLE TEXT] remaining 548 (47%) occurred after more than one person was exposed to the [ILLEGIBLE TEXT] suspected animal (Table 3). Exposure of a single person was more likely [ILLEGIBLE TEXT] bite (p [is less than] 0.001), while group exposure (involving two or more persons) was more associated with nonbites (p [is less than] 0.001). Wild animal species accounted for most [ILLEGIBLE TEXT] exposures--with three exceptions. The largest group exposures (involving 12, 13 people) were associated with the handling of rabid domestic animals (before [ILLEGIBLE TEXT] by veterinary clinic employees.

Table 3. Human rabies postexposure prophylaxis (PEP) in New York State, Epidemiologic characteristics(a)

                                     Group size

                                1           2           3

Characteristic               N    %       N    %      N    %

Number                      625    53    180   15     84    7
No. of sources              625    79     90   11     28    4
Route of exposure
  Bite(b)                   328    52     17    9      4    5
  Nonbite                   296    47    163   91     80   95
  Unknown                     1   0.2      0    0      0    0
Source of exposure
  Dog or cat                273    44     16    9      3    4
  Other domestic species      2   0.3      4    2      3    4
  Raccoon                   235    38    124   69     57   68
  Bat                        39     6     12    7      3    4
  Other wild species         76    12     24   13     18   21
Mean age (yr)              33.4         32.5        24.8

                                 Group size

                                4           5

Characteristic               N    %      N     %

Number                      112   10     60     5
No. of sources               28    4     12     2
Route of exposure
  Bite(b)                     3    3      0     0
  Nonbite                   109   97     60   100
  Unknown                     0    0      0     0
Source of exposure
  Dog or cat                  4    4     10    17
  Other domestic species      4    4      5     8
  Raccoon                    96   86     35    58
  Bat                         0    0      0     0
  Other wild species          8    7     10    17
Mean age (yr)              22.5        21.8

(a) PEP data are from Cayuga, Monroe, Onondaga, and Wayne Counties.

(b) Probability of bite exposure for PEP involving single person vs. group of >1 PEP cases, p <0.00

Rabies Status

The laboratory diagnosis of rabies in the exposing animal was associated with 54 of all PEP cases (445 due to wildlife and 95 due to domestic animals). Eighty-[ILLEGIBLE TEXT] percent of PEP cases attributed to rabid wildlife involved raccoons. In 88 cases, initiated after contact with animals eventually proven nonrabid. In 544 cases [ILLEGIBLE TEXT] administered after contact with animals not tested for rabies. Confirmation of [ILLEGIBLE TEXT] suspect domestic animals occurred in association with 91 (23%) of 390 PEP case resulting from exposure to domestic species, including 40 due to 5 pet cats, 23 to cats, 13 to 1 pet dog, 5 to a domestic rabbit, 7 to a cow, and 3 to a horse. [ILLEGIBLE TEXT] 88 (8%) of all cases PEP was given after encounters with 81 animals [ILLEGIBLE TEXT] nonrabid (35 due to 33 cats, 32 to 32 dogs, 9 to 8 raccoons, 3 to 3 bats, 5 to 2 [ILLEGIBLE TEXT] 1 woodchuck, 1 to 1 squirrel, and 2 to 1 muskrat).

Of 540 cases of PEP associated with animals proven to be rabid, 505 (94%) were suspected saliva exposure; 22 (4%) and 13 (2%) involved bites or scratches, [ILLEGIBLE TEXT] Conversely, 71 (81%) of 88 PEP cases associated with nonrabid animals (i.e., [ILLEGIBLE TEXT] confirmed as negative or confined and observed to be healthy) occurred after bite exposures. Of the 544 PEP cases associated with animals of unknown rabies [ILLEGIBLE TEXT] were due to bites, 45% to suspected saliva contacts, and 7% to scratches.

Wild animals accounted for 98% of the 690 animals submitted and testing [ILLEGIBLE TEXT] rabies in the study area for 1993-94; 613 were raccoons. If animals testing [ILLEGIBLE TEXT] rabies are used as a surrogate for the tree incidence, an approximately 20-fold in PEP cases per rabid domestic animal compared with each rabid wild animal, [ILLEGIBLE TEXT] rural or urban region, is seen (data not shown).

Provoked Exposures

A provoked exposure was characterized by intentional, human-initiated [ILLEGIBLE TEXT] suspect rabid animal. Cases resulting from provoked exposure accounted for 392 of 1,173 of all PEP cases; 248 (63%) involved domestic animals. Most cases [ILLEGIBLE TEXT] from provoked exposure of domestic animals involved cats (162 [65%] of 248) a frequently, dogs (62 [25%] of 248). Wild animals accounted for 144 (37%) PEP from provoked exposure.

Time of PEP Initiation

The interval between exposure to suspect rabid animals and initiation of PEP [ILLEGIBLE TEXT] days (median 2 days). Bite exposures were associated with no delay in treatment; exposures were associated with a 3- to 4-day interval (p [is less than] 0.001).

PEP Regimen

In 1993 and 1994, postexposure biologic products licensed for use in the United were rabies vaccine adsorbed, human diploid cell vaccine (Imovax), and human [ILLEGIBLE TEXT] immune globulin (HRIG; Hyperab or Imogam). As recommended by the [ILLEGIBLE TEXT] Committee on Immunization Practices (ACIP), PEP for the rabies-naive person [ILLEGIBLE TEXT] of HRIG (20 IU/kg) on day 0 and five doses of rabies vaccine administered on [ILLEGIBLE TEXT] 7, 14, and 28 (7). Scheduling information was unavailable for our cases.

Administration of PEP biologic products was recorded as complete in 1,016 (87 1,173 PEP cases. Information regarding completion of the treatment series was [ILLEGIBLE TEXT] available in 15 cases (1%). Appropriate PEP for preimmunized persons consists vaccine doses on days 0 and 3 (7) and was administered to 26 persons, [ILLEGIBLE TEXT] of all cases. Among preimmunized persons, 17 (65%) of 26 PEP cases occurred occupational exposures by 11 veterinary staff personnel (including two group [ILLEGIBLE TEXT] to proven rabid cats), four wildlife rehabilitators, one health department [ILLEGIBLE TEXT] one police officer.

In 54 (5%) instances, PEP was discontinued because of lack of clinical signs in 2 (29 PEP cases) and 23 cats (25 PEP cases) confined for the recommended 10-[ILLEGIBLE TEXT] observation period. Moreover, 34 (3%) PEP cases were discontinued because of negative laboratory results in 10 cats (10 PEP cases), 7 raccoons (8 cases), 2 [ILLEGIBLE TEXT] cases), 4 dogs (4 cases), 3 bats (3 cases), 1 muskrat (2 cases), 1 woodchuck (1 [ILLEGIBLE TEXT] 1 squirrel (1 case).

After PEP was initiated, 29 (2%) of 1,173 refused to complete the series; two [ILLEGIBLE TEXT] adverse reactions. In nine cases PEP deviated from ACIP recommendations: [ILLEGIBLE TEXT] inadvertent scheduling and administration of six total vaccine doses in four [ILLEGIBLE TEXT] intentional omission of HRIG in the treatment regimen of five patients.

Adverse Effects

The categories available for characterizing adverse effects on the state rabies [ILLEGIBLE TEXT] were none, slight, moderate, severe, or unknown. In 596 (51%) of 1,173 PEP [ILLEGIBLE TEXT] information was recorded. Of 577 responses, 495 (86%) reported no adverse [ILLEGIBLE TEXT] resulting from PEP. Adverse effects were characterized as slight by 67 (12%) [ILLEGIBLE TEXT] Moderate adverse reactions including vomiting, nausea, fever, aches, and [ILLEGIBLE TEXT] reported by 13 (2%) persons. Serious systemic adverse reactions, recorded as anaphylactic shock and serum sickness, occurred in two (0.2%) persons. Both of patients had received HRIG; PEP was discontinued after one and two vaccine do each case.

Conclusions

The most important finding of this study was that in most cases PEP was [ILLEGIBLE TEXT] because of suspected nonbite, indirect exposure to animal saliva, a route convent thought of nearly negligible risk in rabies transmission (7,8). Because of [ILLEGIBLE TEXT] public health personnel and health-care workers are primarily challenged with [ILLEGIBLE TEXT] assessment of exposure to rabies, rather than with treatment of human cases of [ILLEGIBLE TEXT] disease. Assessment of nonbite saliva exposures are particularly time-consuming should consist of a thorough, but nonleading, history-taking that elicits the [ILLEGIBLE TEXT] confirmation of mucous membrane or nonintact skin contact and a realistic [ILLEGIBLE TEXT] the potential presence of infectious saliva on surfaces or pets. Given the [ILLEGIBLE TEXT] outcome of clinical rabies, the tendency may be to administer PEP, even without indication of exposure. This tendency may be unwise--not only for economic [ILLEGIBLE TEXT] but also because, despite their relative innocuity and high potency, modern rabie products, are not risk-free, nor is their supply unlimited.

The first descriptive study of PEP cases associated with the mid-Atlantic raccoon epizootic during 1982-83 (133 patients) also documented that most PEP cases [ILLEGIBLE TEXT] nonbite exposures; however, these principally involved direct exposure to the [ILLEGIBLE TEXT] rabid animal (1).

A 1980-81 nationwide survey of 5,634 PEP cases found an increased risk for occupational and recreational exposure to animals in a rural setting (9). The [ILLEGIBLE TEXT] mean annual PEP rate described in our report of 43 per 100,000 was nearly 10- [ILLEGIBLE TEXT] than the rate of 4.7 per 100,000 reported in that study. A rate of 66 per 100,000 reported from two counties (93 people per square kilometer) in New Jersey at the rabies epizootic front in 1990 (10,11). The incidence of human rabies PEP in [ILLEGIBLE TEXT] and this study exceeded by 10- to 20-fold the rates in areas reporting rabies in [ILLEGIBLE TEXT] (12,13), raccoons (14), and mixed wildlife (9,15). The disparity may be partially explained by regional epizootic versus enzootic status of wildlife rabies and [ILLEGIBLE TEXT] variations in the comparative intensity of disease in wildlife populations, as well increases in both human and animal population densities and their close association suburban settings (2). The previous PEP studies involved communities in which had been enzootic in terrestrial wildlife for decades (9,1.2-16). However, the [ILLEGIBLE TEXT] raccoon rabies epizootic comprises the emergence of a terrestrial rabies variant [ILLEGIBLE TEXT] that had, for the most part, been free of terrestrial rabies. The exceptions were [ILLEGIBLE TEXT] cases of spillover from geographically widespread, but low-level, bat rabies into terrestrial animals and occasional incursions of red fox rabies from Canada into York, Vermont, and other northern states (2,16).

Previous studies of PEP trends in the United States identified bites from dogs [ILLEGIBLE TEXT] the most common animal encounter, accounting for 65% to 84% of PEP cases (7 15). By contrast, only 23% of PEP cases in this study were associated with dog [ILLEGIBLE TEXT] bites. In view of current epidemiologic trends in canine rabies-free areas of the [ILLEGIBLE TEXT] States, if a biting dog appears clinically normal and can be confined and observe signs of rabies, the decision to administer PEP may be based on suggestive clinic and a prompt diagnostic evaluation that confirms rabies rather than on [ILLEGIBLE TEXT] initiating PEP. Given that cats are now the leading rabid domestic animal in the States (17), and more specifically that 12 of the 13 domestic species confirmed [ILLEGIBLE TEXT] the four-county study area during 1993 and 1994 were cats, rabies vaccinations [ILLEGIBLE TEXT] should become more prevalent. Among exposures to owned domestic pets that [ILLEGIBLE TEXT] human PEP, 9% of cats (versus 76% of dogs) were vaccinated against rabies. [ILLEGIBLE TEXT] most of the encounters with dogs that precipitated PEP in urban counties involve from stray dogs, indicating the need for enhanced programs for urban dog [ILLEGIBLE TEXT]

The economic impact of a new terrestrial rabies variant is substantial (2,18). In 1 New York State Department of Health increased its reimbursement to local [ILLEGIBLE TEXT] for mandated rabies control activities from $75,000 to $1,080,000 to assist in the associated with human rabies PEP, animal rabies testing (11,896 specimens in 19 pet immunization clinics (114 in 1993) (4). Local health units in New York State funds for treatment expenses not covered by health insurance. With the cost of [ILLEGIBLE TEXT] biologic products alone exceeding $1,500 per treatment series, an exponential in the incidence of PEP, as documented in this study, taxes the public health [ILLEGIBLE TEXT] Moreover, unlike red fox rabies, which periodically reinvades northeastern New from adjoining areas of Canada and Vermont but then dies out, raccoon rabies is to persist in affected areas of New York State, as it has in the southeastern Unite for the past 5 decades and in the mid-Atlantic and northeastern states more [ILLEGIBLE TEXT]

Control of canine rabies in the United States and other industrialized countries [ILLEGIBLE TEXT] achieved by eliminating the susceptible reservoir population (through stray dog [ILLEGIBLE TEXT] and mandatory vaccination) (16). Applications of this concept to wildlife is [ILLEGIBLE TEXT] because of the difficulty in capturing wild animals for vaccination or for [ILLEGIBLE TEXT] measures. Population reduction alone is not sufficient to control or eliminate [ILLEGIBLE TEXT] wildlife rabies variants over large geographic areas (16). An emerging alternative rabies vaccination of free-ranging reservoir populations, although current [ILLEGIBLE TEXT] still in their infancy and the cost-benefit of such interventions warrants further investigation (10).

During the enzootic raccoon rabies in the southeastern states since the early 1950 current mid-Atlantic/northeastern United States epizootic, this variant has not be known to cause human rabies deaths. Yet its potential lethality for humans is [ILLEGIBLE TEXT] by ample spillover into other wild animal species (predominantly skunks, but [ILLEGIBLE TEXT] foxes, bobcats, and woodchucks) and into domestic animals (predominantly cats, dogs, cows, horses, goats, and rabbits). Substantial amounts of infectious rabies have been identified in the salivary glands of rabid raccoons (19). No biologic or epidemiologic data suggest unique attenuation or change in virulence of this part rabies variant that would account for a lack of identified human deaths. Instead, epidemiologic data regarding PEP after suspected exposure to raccoon rabies [ILLEGIBLE TEXT] PEP frequently is administered even when no exposure has been identified. Also, scratch, or other exposure, such as gross contamination of an open wound or [ILLEGIBLE TEXT] membrane with moist, infectious material from a small carnivore such as the [ILLEGIBLE TEXT] would unlikely be unrecognized or ignored. The apparent liberal administration effective PEP after known bites, scratches, and other suspected exposures from [ILLEGIBLE TEXT] raccoons may have resulted in complete prevention of human deaths due to this rabies virus associated with raccoons.

Although the Healthy People 2000 goal to reduce PEP is worthwhile, better understanding of the circumstances leading to human exposure and formulating reduce exposure is required to meet this objective. Until then, it will be particular difficult to reduce PEP during an ever-expanding raccoon rabies epizootic.

Acknowledgments

We thank the following public health nurses and rabies coordinators for data collection and generosity and enthusiasm in sharing data: Terri Hogan, Lynn Crane, Linda Thompson, and [ILLEGIBLE TEXT]

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This page last reviewed July 1, 1999

Emerging Infectious Diseases Journal National Center for Infectious Diseases Centers for Disease Control and Prevention

URL: http://www.cdc.gov/ncidod/eid/vol5no3/wyatt.htm

Jeffrey D. Wyatt,(*) William H. Barker,(*) Nancy M. Bennett,([dagger]) and Cathleen Hanlon([double dagger])

(*) University of Rochester School of Medicine & Dentistry, Rochester, New York ([dagger]) Monroe County Department of Health, Rochester, New York, USA; ([double dagger]) Centers [ILLEGIBLE TEXT] Disease Control & Prevention, Atlanta, Georgia, USA

Dr. Wyatt is chair of the University of Rochester School of Medicine and Dentistry's [ILLEGIBLE TEXT] Laboratory Animal Medicine and chief veterinarian at the Seneca Park Zoo in Rochester, New [ILLEGIBLE TEXT] research interests include the epidemiology of zoonoses in the environment and the workplace.

Address for correspondence: Jeff Wyatt, University of Rochester, Box 674, Rochester, New 14642, USA; fax: [phone]; e-mail: [e-mail].