Rabies, one of the oldest known diseases affecting humans, is an acute, fatal viral zoonosis most often transmitted through the bite of a rabid mammal. This vaccine-preventable disease is 100% fatal once symptoms appear. In the United States, rabies is maintained in distinct variants associated with bat, raccoon, striped skunk, gray fox, arctic fox and mongoose populations. The globally recognized modern approach to controlling wild carnivore rabies is by a strategy called oral rabies vaccination.
Although human rabies deaths are now rare in the United States and are mostly acquired during travel abroad to areas affected by canine rabies or domestically from native bat species, there are significant impacts associated with the disease in the United States. Among all wildlife rabies reservoirs described in the United States, including various bats, raccoon rabies has the highest rate of spillover infections to domestic animals and wildlife and consequently is associated with the greatest burden of human exposures which may require post-exposure treatment. Current data estimate that approximately 55,000 persons seek post-exposure treatment in the United States each year, with cumulative costs in excess of $200 million. If rabies variants such as those transmitted by raccoons are not prevented from spreading to new areas of the United States, the health threats and costs associated with rabies could increase substantially as broader geographic areas are affected.
The United States also enjoys a canine-rabies free status since 2007 following the elimination of the dog-coyote rabies variant in Texas by oral rabies vaccine baiting. This status is maintained by an oral rabies vaccine barrier along the United States-Mexico border to prevent the re-introduction of the dog-coyote rabies variant into the United States coyote population.
A single vaccine is licensed for use with coyotes and raccoons in the US, which is a vaccinia rabies virus recombinant vaccine (RABORAL V-RG®). Since 2011, the NWRC and National Rabies Management Program (NRMP) have collaborated with WS state programs and industry to evaluate a new Canadian vaccine product in the field, and those experimental trials are near complete. The NRMP has also outlined strategies for elimination of raccoon rabies by 2053 and one key ongoing NWRC activity focuses on raccoon rabies elimination modeling based on public health and enhanced rabies surveillance data. Other ongoing studies include novel oral rabies vaccine bait development targeting skunks and raccoons; development and testing of oral rabies vaccination products and strategies for mongooses in Puerto Rico; using advanced genetic tools to understand the movements and ecology of raccoons, gray foxes and mongooses; and refinements to systems and strategies for vaccine delivery to free-ranging meso-carnivores in developed landscapes.
Dr. Amy Gilbert
Fort Collins, Colorado 80521