ORAL RABIES VACCINATION: REDUCING ECONOMIC UNCERTAINTY VIA RESPONSE SURFACE ANALYSIS

Abstract

Economic uncertainty surrounds the distribution of Raboral V-RG7 as an oral rabies vaccine (ORV) bait for the containment or elimination of raccoon-variant rabies in the United States. This paper describes a costs-savings model of ORV. It also describes Excel XP7 code that was prepared to compute potential net savings (NS) and benefit-cost ratios (BCRs) associated with Raboral V-RG7 bait distributions. Currently, baits and bait distributions are relatively expensive; individual baits are produced at a cost of $1.27 for federal use and typically dispensed at \u3e75 baits/km2. Distribution is estimated at$8.62/km2, $15.80/km2, and$33.30/km2 for fixed-winged (FW), ground (Gnd), and rotary-winged (RW) applications, respectively. Although many assumptions are required, iterative runs of the code allow plotting NS and BCR response surfaces for diverse scenarios based on 6 ORV variables: area (km2), bait-price (US/vaccine bait), bait-density (#/km2), application frequency (n), mode-of-delivery [US for % fixed-winged (FW), % rotarywinged (RW), and % ground-dispensed (Gnd)], and effectiveness (% seropositive titer conversion). Using a raccoon-rabies-epizootic-containment scenario for parts of Pennsylvania and a modest epizootic cost estimate of $40 million, the greatest NS ($6.4 to 38.4 million) and BCR (2.85 to 25.76) indices occurred for a one-time bait distribution involving FW aircraft over a fourth of the state with a $0.90/bait price. As expected, greater reliance on the more expensive RW and Gnd modes of bait distribution compared to FW aircraft, coupled with higher bait prices and higher bait densities, decreased NS and BCR indices. The utility of the approach to economic forecasting and decision making of ORV effects are discussed