Tactics and economics of wildlife oral rabies vaccination, Canada and the United States.

Progressive elimination of rabies in wildlife has been a general strategy in Canada and the United States; common campaign tactics are trap-vaccinate-release (TVR), point infection control (PIC), and oral rabies vaccination (ORV). TVR and PIC are labor intensive and the most expensive tactics per unit area (approximately $616/km(2) [in 2008 Can$, converted from the reported $450/km(2) in 1991 Can$] and approximately $612/km(2) [$500/km(2) in 1999 Can$], respectively), but these tactics have proven crucial to elimination of raccoon rabies in Canada and to maintenance of ORV zones for preventing the spread of raccoon rabies in the United States. Economic assessments have shown that during rabies epizootics, costs of human postexposure prophylaxis, pet vaccination, public health, and animal control spike. Modeling studies, involving diverse assumptions, have shown that ORV programs can be cost-efficient and yield benefit:cost ratios >1.0.

Benefit cost scenarios of potential oral rabies vaccination for skunks in California.

Scenario-based analyses were computed for benefits and costs linked with hypothetical oral rabies vaccination (ORV) campaigns to contain or eliminate skunk-variant rabies in skunks (Mephitis mephitis) in California, USA. Scenario 1 assumed baiting eight zones (43,388 km(2) total) that comprised 73% of known skunk rabies locations in the state. Scenario 2 also assumed baiting these eight zones, but further assumed that added benefits would result from preventing the spread of skunk-variant rabies into Los Angeles County, USA. Scenarios assumed a fixed bait cost ($1.24 each) but varied campaigns (one, two and three annual ORV applications), densities of baits (37.5/km(2), 75/km(2) and 150/km(2)), levels of prevention (50%, 75%, and 100%), and contingency expenditures if rabies recurred (20%, 40%, and 60% of campaign costs). Prorating potential annual benefits during a 12-yr time horizon yielded benefit-cost ratios (BCRs) between 0.16 and 2.91 and between 0.34 and 6.35 for Scenarios 1 and 2, respectively. Economic issues relevant to potentially managing skunk-variant rabies with ORV are discussed.

Economic evaluation of an oral rabies vaccination program for control of a domestic dog-coyote rabies epizootic: 1995-2006.

OBJECTIVE: To conduct a benefit-cost analysis of the results of the domestic dog and coyote (DDC) oral rabies vaccine (ORV) program in Texas from 1995 through 2006 by use of fiscal records and relevant public health data. DESIGN: Retrospective benefit-cost analysis. Procedures-Pertinent economic data were collected in 20 counties of south Texas affected by a DDC-variant rabies epizootic. The costs and benefits afforded by a DDC ORV program were then calculated. Costs were the total expenditures of the ORV program. Benefits were the savings associated with the number of potentially prevented human postexposure prophylaxis (PEP) treatments and animal rabies tests for the DDC-variant rabies virus in the epizootic area and an area of potential disease expansion. RESULTS: Total estimated benefits of the program approximately ranged from $89 million to $346 million, with total program costs of $26,358,221 for the study period. The estimated savings (ie, damages avoided) from extrapolated numbers of PEP treatments and animal rabies tests yielded benefit-cost ratios that ranged from 3.38 to 13.12 for various frequen-cies of PEP and animal testing. CONCLUSIONS AND CLINICAL RELEVANCE: In Texas, the use of ORV stopped the northward spread and led to the progressive elimination of the DDC variant of rabies in coyotes (Canis latrans). The decision to implement an ORV program was cost-efficient, although many unknowns were involved in the original decision, and key economic variables were identified for consideration in future planning of ORV programs.

Skunk rabies in California (1992-2003)--implications for oral rabies vaccination.

Skunk-variant rabies is endemic in California (United States), and the development of oral vaccines and baits to vaccinate skunks is in progress. In 2003, the California Department of Public Health (CDPH) began to quantify the impacts of skunk-variant rabies and to assess the feasibility of using oral rabies vaccination (ORV) as a containment measure. The CDPH rabies case data for skunks were spatially depicted and analyzed using a geographic information system. Statewide, rabid skunks (1992-2003) primarily occurred in seven physiographic regions: Central Coast, North Coast, North Sierra, Sacramento Valley, San Francisco Bay and Delta, San Joaquin Valley, and South Sierra. Detailed analysis of rabid skunks in San Luis Obispo (SLO) and Santa Barbara (SB) counties showed that skunk rabies was endemic in the coastal plain of SLO County between 1992 and 2000, but only became epizootic in SB County during 2002. Despite the widespread distribution of striped skunks (Mephitis mephitis) throughout most of California, the skunk rabies variant has not been found in Los Angeles County since 1979. Results imply that future ORV campaigns for skunk-variant rabies in the Pacific Coastal Plain could deter spread from SLO into SB County, as well as deterring the reintroduction of skunk-variant rabies into southern California.

Direct and indirect costs of rabies exposure: a retrospective study in southern California (1998-2002).

The direct and indirect costs of suspected human rabies exposure were estimated for San Luis Obispo and Santa Barbara counties, California, USA. Clinic, hospital, and county public health records (1998-2002) were examined to determine direct costs for postexposure prophylaxis (PEP), and 55 (41%) former patients were contacted to voluntarily provide estimates of their indirect costs associated with receiving PEP. Additional costs due to public health and animal control personnel responses to rabid animals were collected, including diagnostic testing and wages. The mean total cost of a suspected human rabies exposure was $3,688, the direct costs per case were $2,564, and the indirect costs were $1,124 of that total. About one third of the total cost for suspected human rabies exposure was attributed to indirect costs (e.g., lost wages, transportation, and day-care fees), most of which were not reimbursable to the patient.

Capsicum oleoresin: development of an in-soil repellent for pocket gophers.

A pre- and post-monitoring study was conducted of the potential use of capsicum oleoresin as an in-soil repellent for northern pocket gophers (Thomomys talpoides). Pocket gophers were captured in irrigated alfalfa (Medicago sativa L), affixed with radio transmitters, and monitored daily for location. Six plots (4.87 x 4.87 m) each were randomly assigned to capsicum oleoresin and soybean oil treatments; these were set up based upon the centers of initial core areas of gophers. Mean (+/-SD) volumes of capsicum oleoresin and water and soybean oil and water mixtures (10 + 90 by volume) dispensed onto plots equaled 178.5 (+/-4.7) and 175.7 (+/-14.0) liters, respectively. Movements (m) of the radio-transmitted gophers from plot centers were computed for four daily readings (i.e., 0801-1000, 1101-1300, 1501-1700 and 1801-2000 h). Spectrophotometric analysis of soil samples from capsicum oleoresin plots validated the presence of capsicum on plots and the absence of capsicum on placebo- and off-plot locations. Analysis of variance for movement distances of gophers yielded a Date main effect [F(11, 103) = 2.08, P < or = 0.03] and a Date x Reading (time) interaction [F(32, 299) = 3.21, P < or = 0.01]. Results showed that gophers were located farther from plot centers for the 0801-1000 and 1501-1700 h telemetry readings for < or =3 days post-chemical application-a probable 'disturbance' effect rather than a chemical-induced avoidance. In a prior laboratory study, capsicum oleoresin and soil treatments of 1.5% w/w capsicum caused nearly a 50% decrease in soil contact time by gophers relative to placebo-exposed control animals. This implies that procedural variables warrant revision before abandoning this approach. The potential for soil insertion of repellents as a technique for expelling pocket gophers from territories and some methodological changes for future research of the technique are discussed.

An index technique to monitor broadcast calibration and bait pick up, plus rodent and avian sign under arid conditions.

As part of product-performance and wildlife-hazards studies of 2% zinc phosphide (Zn3P2) steam-rolled-oat baits (11.2 kg ha-1) to reduce vole populations (Microtus spp) in alfalfa (Medicago sativa), we used randomly located, brushed-dirt plots (eight approximately 930-cm2 plots per 0.2-ha enclosure) to monitor bait-broadcast and -removal patterns, as well as to index vole and avian sign. Research was conducted in 18 x 0.2-ha enclosures containing 2.5-year-old stands of alfalfa; a 2-day pre-bait (placebo baits broadcast in all enclosures) period followed by a 14-day test-bait period (placebo and 2% Zn3P2 baits in nine enclosures each) characterized the bait exposures. Baits were broadcast manually by two certified pesticide applicators (CPAs) using Spyker Model-75 spreaders. Baits that fell onto plots were counted < 30 min later to assess the uniformity of bait distribution. The main statistical design was a 2 (placebo or Zn3P2 baits) x 3 (vole-only, vole-pheasant, vole-quail exposures) x 14 (days) factorial, with days considered repeated measurements. In the six vole-only enclosures, baits were removed from the brushed-dirt plots and replaced with four 0% or 2% Zn3P2 baits (one per 232.6-cm2 quadrant; 32 per enclosure); these 'placed' baits were then monitored daily for removal, while the surfaces of all plots were monitored daily for the presence:absence of animal/bird sign. Key results were: (a) 3.51 (+/- 2.66) and 3.39 (+/- 3.52) mean (+/- SD) baits were found on plots after pre-bait and test-bait broadcasts, respectively--less than the predicted 4.52 particles per 930-cm2 plot; (b) baits 'placed' on plots in placebo-baited enclosures were removed earlier than those in Zn3P2-baited enclosures--data in agreement with observed vole mortality; and (c) species x bait interactions occurred for both the vole- and pheasant-sign counts, but not quail-sign counts--data also indirectly confirming Zn3P2-induced mortality effects on voles and pheasants. This technique has utility for a variety of wildlife biology and chemical registration studies; although limited to arid conditions, the technique affords useful indices of broadcast calibration, bait pick-up, as well as target and non-target species mortality.