A bite out of the budget? Costs and characteristics of animal bites in Benton County, Oregon.

Introduction

Animal bites are a largely preventable, yet often overlooked environmental health problem. Of particular concern are bites by animals that are susceptible to rabies. These animals include, but are not limited to: cats, dogs, bats, foxes, raccoons, ferrets, and skunks (1-11). Other health problems include bacterial infections, disfigurement, scarring, and emotional stress.

All bites inflicted by animals susceptible to rabies are reportable by law to the county health department in Oregon for a follow-up rabies investigation (12). In Benton County, a rural county with a population of 71,500, previous studies of reported animal bites showed approximately 66 percent of animal bites from dogs, 25 percent from cats, six percent from other domestic animals, and fewer than three percent from wild animals (Benton County Health Department data). These statistics are comparable to statistics from published studies of animal bite characteristics (13-19). All dogs in Benton County are required to be licensed and vaccinated against rabies; however, this law is difficult to enforce. Vaccinations for cats and other domestic outdoor animals, such as horses, are highly recommended but not required. In most cases, vaccinating wild animals is not feasible.

In cases of bites by domestic animals in Oregon, regardless of rabies immunization status, a 10-day quarantine for observation is required. Quarantine usually occurs at home if the animal was immunized, and the bite was provoked. In other cases, quarantine occurs in a humane society or veterinarian's office. The only exception to quarantine is the case of an unprovoked bite to the face by an unvaccinated animal. In this situation, the animal may be destroyed and the body submitted to a laboratory for rabies virus testing.

Numerous studies have examined the animal, bite, attack and victim characteristics, though few have examined the impact of animal bites on the local environmental health department's resources (13-26). The direct costs associated with coordinating and directing the bite investigations are unknown. These activities include questioning the victim, verifying any medical treatment given, enforcing quarantine, and working with other agencies that have an interest in the bite occurrence and outcome. The published studies that have reported cost data focused on the medical costs of animal bites and rabies prevention, such as pre- and post-exposure prophylaxis treatments, rather than on costs to the environmental health department (25, 27-30). The primary objective of this study was to assess the time and monetary impact of animal bites on the local health department. A secondary objective was to examine the characteristics of animal bites in Benton County, Oregon.

Methods

Animal Bite Characteristics

To determine the characteristics of animal bites in Benton County, 1993 and 1994 animal bite data were entered into a computer spreadsheet program (Microsoft Excel 5.0). The data were sorted to obtain information about the victim, bite, attack, animal, and investigation characteristics.

In addition to the data from 1993 and 1994, the total numbers of bites reported during the years 1985 through 1992 were tabulated from the bite report summary Sheets in order to assess any trend in bite incidence.

Time and Monetary Impact of Animal Bites

To determine the time and monetary impact of animal bites on the Environmental Health Division of the Benton County Health Department, the weekly time logs of the sanitarian in charge of investigating animal bites were examined, and the time spent each week on investigations was recorded.

A complete year of full-time work for one individual (1.0 full-time equivalent or FTE) is 2,080 hours. Productivity studies in the health department have shown that approximately 60 percent of this time, or 1,248 hours, is available for direct service work (personal communication). The percentage of direct service time that the sanitarian in charge of animal bites spent on bites was estimated by dividing the number of hours per year spent investigating bites by the number of direct service hours per year (1,248).

The cost of investigating animal bites each year was estimated as follows. First, the total yearly expenditures for the Environmental Health Division of Benton County were determined by summing the Environmental Health Division expenditures (salaries for 4.8 direct service employees, 0.7 supervisor/administrator employees, 2.0 support employees, supplies, training, travel, and building space) and the Division's share of Health Department overhead and Benton County overhead.

Then, this sum was divided by the number of employees available to do direct service work to determine the cost per full-time equivalent (FTE). The cost per FTE divided by the number of direct service hours available per FTE resulted in the cost per hour of direct service work. The yearly cost was calculated by multiplying this number by the average number of hours spent per year on animal bite investigations.

Results

Animal Bite Rate

Figure 1 shows animal bite rates in Benton County for the years 1985 through 1994. In 1988, there was a dramatic increase in the animal bite rate, probably as a result of a local sanitarian's contact with various agencies in the community (such as the police departments, medical centers, and humane societies) to remind them that all animal bites, by law, must be reported to the county health department.

Table 1 shows the animal bite rate by age group. The rates calculated are for the number of bites per 100,000 person-years for the years 1993 and 1994 combined. The age groups from 0 to 17 years have the highest reported bite rate, 2.2 to 6.4 times the rates in the 18- to 29-year age groups.

Of the 247 people bitten by animals in 1993 and 1994, an average of 54 percent of the victims were female and 46 percent were male. Results of the two years were virtually identical. The gender distribution differed by the type of animal bite. Among dog bite victims, 58 percent were male and 42 percent were female while among cat bite victims, 15 percent were male and 85 percent were female ([P.sub.2][less than]0.001).

The 247 people bitten by animals in 1993 and 1994 were inflicted by 243 different animals. Dogs accounted for 70 percent of the total reported animal bites, and cats accounted for 25 percent. The remaining five percent of bites were inflicted by ferrets (two percent) and rats, bats, skunks, mice (three percent).

Time and Monetary Impact of Animal Bites

The total time spent investigating animal bites was 65.75 hours in 1993 and 61.94 hours in 1994, and averaged 0.52 hours per case overall. Based on the average employee spending 60 percent of his or her time (1,248 hours) doing direct service work, in Benton County 5.1 percent of one sanitarian's direct service time was spent investigating animal bites.

For the fiscal year 1993-94, the total direct expenditures for the Environmental Health Division were $385,768. Adding in Benton County Health Department overhead ($24,613) and Benton County overhead ($39,366), the total yearly expenditures came to $449,747. With 4.8 FTE available to do direct service work for the Environmental Health Division, the total cost per FTE was $93,697 per year, and the cost per hour of direct service work was $75. Thus, the cost of an average animal bite investigation was $39 (0.52 times $75). The cost of animal bite investigations was estimated to have been $4,931 in 1993 and $4,647 in 1994 with an average total cost per year equal to $4,789. This figure is 1.1 percent of the total yearly expenditures and 1.2 percent of the total direct expenditures of the Environmental Health Division.

Discussion

The cost of investigating animal bites each year was approximately $4,800. This amount, while not large, was estimated to have taken 5.1 percent of one sanitarian's direct service time and 1.2 percent of the Environmental Health Division's total direct expenditures each year. The Benton County Environmental Health Division receives 80 percent of its revenue from fee and grant programs, thus 80 percent of the available FTE is devoted to fee activities such as inspections, permits, and grant assurances. The remaining revenue comes from general fund tax dollars, thus leaving only 20 percent of the Environmental Health Division's 4.8 FTE (approximately 1.0 FTE) for non-fee activities such as investigation of animal bites, communicable disease, health hazards, emergency response, etc.

At first glance, 5.1 percent of one sanitarian's direct service time may not seem to constitute a large part of a county Environmental Health Division budget. However, 5.1 percent becomes significant when there is only 1.0 FTE to perform non-fee activities such as animal bites. In addition, recent tax control measures in Oregon will mean a reduction in general fund revenue and in FTE available to perform non-fee activities. Some counties in Oregon already operate their Environmental Health Divisions without general fund revenue and struggle with how to respond to animal bites. For an incident that is largely preventable, the cost of investigating animal bites represents a significant part of the yearly budget and personnel of a small county health department.

One area of potential savings identified by the study relates to the severity of bites. Thirty-two of the victims reported bite wounds no more severe than "skin unbroken" or "scratch." Although studies have shown that, "[c]ases of rabies after scratches, abrasion, or the licking of open wounds or mucous membranes are extremely rare," 26 of the 32 animals inflicting these injuries (81 percent) were quarantined (31-33). If animals inflicting no more than scratches could be exempt from investigation and quarantining, over $600 or 0.16 percent of the Environmental Health total direct expenditures could be saved per year.

Future studies of animal bites should focus on distinguishing the characteristics and amount of time spent on particular types of animal bite cases. For example, it rarely was recorded on the bite report whether the dog was licensed or not, and the vaccination status of the dogs and cats often was unknown (23 percent and 56 percent, respectively). Also useful would be an assessment of the amount of time a particular animal bite investigation takes according to the type of animal or vaccination status. Knowing how these characteristics affect investigation needs would help determine what types of preventative measures might reduce animal bites and costs of investigations, and provide justification for policies such as licensing and vaccination of animals.

TABLE 1

Animal bite rates for the years 1993 and 1994

Age group             Animal bite rate per
in years              100,000 person-years

0 to 4                         363
5 to 9                         284
10 to 14                       264
15 to 17                       200
18 to 19                        57
20 to 24                        69
25 to 29                        89
30 to 34                       128
35 to 39                       123
40 to 44                       105
45 to 49                       157
50 to 59                       115
60+                             68
TABLE 2

Animal bite report originations in Benton County for 1993 and
1994 total

Report Origination                         Percent

Medical center                                 25%
Police                                         26%
Victims                                        23%
County Animal Controls                         14%
Humane Societies + Clinics                      5%
Animal owner                                    3%
Other Health Dept.'s                            1%
Total                                         100%

Corresponding Author: Holly R. Sherburne, M.S., Environmental Health Sciences Center, 1011 ALS, Corvallis, OR 97331-7302. Email: [e-mail]. At the time of this study, the author was a graduate student in the Department of Public Health, Oregon State University.