Oral vaccination of wildlife using a vaccinia-rabies-glycoprotein recombinant virus vaccine (RABORAL V-RG®): a global review.

RABORAL V-RG® is an oral rabies vaccine bait that contains an attenuated ("modified-live") recombinant vaccinia virus vector vaccine expressing the rabies virus glycoprotein gene (V-RG). Approximately 250 million doses have been distributed globally since 1987 without any reports of adverse reactions in wildlife or domestic animals since the first licensed recombinant oral rabies vaccine (ORV) was released into the environment to immunize wildlife populations against rabies. V-RG is genetically stable, is not detected in the oral cavity beyond 48 h after ingestion, is not shed by vaccinates into the environment, and has been tested for thermostability under a range of laboratory and field conditions. Safety of V-RG has been evaluated in over 50 vertebrate species, including non-human primates, with no adverse effects observed regardless of route or dose. Immunogenicity and efficacy have been demonstrated under laboratory and field conditions in multiple target species (including fox, raccoon, coyote, skunk, raccoon dog, and jackal). The liquid vaccine is packaged inside edible baits (i.e., RABORAL V-RG, the vaccine-bait product) which are distributed into wildlife habitats for consumption by target species. Field application of RABORAL V-RG has contributed to the elimination of wildlife rabies from three European countries (Belgium, France and Luxembourg) and of the dog/coyote rabies virus variant from the United States of America (USA). An oral rabies vaccination program in west-central Texas has essentially eliminated the gray fox rabies virus variant from Texas with the last case reported in a cow during 2009. A long-term ORV barrier program in the USA using RABORAL V-RG is preventing substantial geographic expansion of the raccoon rabies virus variant. RABORAL V-RG has also been used to control wildlife rabies in Israel for more than a decade. This paper: (1) reviews the development and historical use of RABORAL V-RG; (2) highlights wildlife rabies control programs using the vaccine in multiple species and countries; and (3) discusses current and future challenges faced by programs seeking to control or eliminate wildlife rabies.

Epidemiology of rabies in bats in Texas (2001-2010).

OBJECTIVE: To obtain epidemiological information on rabies in bats in Texas. DESIGN: Epidemiological study. SAMPLE: Laboratory reports of bats that had been submitted for rabies testing in Texas from 2001 through 2010. PROCEDURES: Laboratory reports were reviewed to obtain information on seasonality of rabies in bats; distribution, species, and rabies virus variants of rabid bats; and human and domestic animal exposures to rabid bats. RESULTS: The number of rabid bats during the first 5 years of the study period remained static until a > 2-fold increase in 2006; during the subsequent 4 years, the annual number of rabid bats remained at this higher level, including a peak in 2008. The highest proportions of rabid bats were seen in late summer and early fall. The Brazilian free-tailed bat (Tadarida brasiliensis) was the most often affected species. Additionally, the rabies virus variant associated with the Brazilian free-tailed bat was the most prevalent. The percentage of rabid bats from urban areas was greater than that from rural areas. Dogs and cats were the domestic animals most frequently exposed to rabid bats. Most humans exposed to rabid bats did not report a known bite or scratch. The highest numbers of humans exposed to rabid bats were males between 11 to 15 years old. CONCLUSIONS AND CLINICAL RELEVANCE: Information on the epidemiology of rabies in bats and the epidemiology of exposures to rabid bats may be useful in planning and implementing local, state, and national rabies control and prevention campaigns and in encouraging rabies vaccination of domestic animals.

Evaluation of a postexposure rabies prophylaxis protocol for domestic animals in Texas: 2000-2009.

OBJECTIVE: To determine whether postexposure rabies prophylaxis (PEP) in domestic animals, as mandated in Texas, has continued to be effective and to evaluate preexposure or postexposure vaccination failures from 2000 through 2009. DESIGN: Retrospective case series. ANIMALS: 1,014 unvaccinated domestic animals (769 dogs, 126 cats, 72 horses, 39 cattle, 3 sheep, 4 goats, and 1 llama) that received PEP and 12 vaccinated domestic animals (7 dogs and 5 cats) with possible failure of protection. PROCEDURES: Zoonotic incident reports from 2000 through 2009 were reviewed for information regarding unvaccinated domestic animals that received PEP in accordance with the state protocol after exposure to a laboratory-confirmed rabid animal; reports also were reviewed for any preexposure or postexposure vaccination failures. The state-required PEP protocol was as follows: immediately vaccinate the animal against rabies, isolate the animal for 90 days, and administer booster vaccinations during the third and eighth weeks of the isolation period. RESULTS: From 2000 through 2009, 1,014 animals received PEP; no failures were recorded. One preexposure vaccination failure was recorded. CONCLUSIONS AND CLINICAL RELEVANCE: The Texas PEP protocol was used during the 10-year period. Results indicated that an effective PEP protocol for unvaccinated domestic animals exposed to rabies was immediate vaccination against rabies, a strict isolation period of 90 days, and administration of booster vaccinations during the third and eighth weeks of the isolation period.

Epidemiology of rabies in skunks in Texas.

OBJECTIVE: To obtain epidemiologic information on rabies in skunks in Texas. DESIGN: Epidemiologic study. SAMPLE POPULATION: Reports of skunks that had been submitted for rabies testing in Texas from 1953 through 2007. PROCEDURES: Reports were reviewed to obtain information on seasonality of rabies in skunks, seasonality of human and domestic animal exposure to rabid skunks, commonly reported clinical signs of rabies in skunks, domestic animals frequently exposed to rabid skunks, common scenarios for exposure of domestic animals to rabid skunks, disposition of domestic animals exposed to rabid skunks, age and gender of humans exposed to rabid skunks, and usual routes of exposure of humans to rabid skunks. RESULTS: On a yearly basis, the number of rabid skunks peaked in 1961, 1979, and 2001. On a monthly basis, the number of rabid skunks peaked in March and April. Over the study period, the percentage of rabid skunks from urban areas increased and the percentage from rural areas decreased. Striped skunks were the most common species. Dogs and cats were the domestic animals most frequently exposed to rabid skunks. On average, the highest numbers of humans exposed to rabid skunks were between 36 and 50 years old. Most humans were exposed through means other than a bite. Typical behaviors of rabid skunks were entering a dog pen, appearing outside during daytime, and attacking pets. CONCLUSIONS AND CLINICAL RELEVANCE: Information on the epidemiology of rabies in skunks may be useful in planning and implementing local, state, and national rabies control and prevention campaigns.

Enzootic rabies elimination from dogs and reemergence in wild terrestrial carnivores, United States.

To provide molecular and virologic evidence that domestic dog rabies is no longer enzootic to the United States and to identify putative relatives of dog-related rabies viruses (RVs) circulating in other carnivores, we studied RVs associated with recent and historic dog rabies enzootics worldwide. Molecular, phylogenetic, and epizootiologic evidence shows that domestic dog rabies is no longer enzootic to the United States. Nonetheless, our data suggest that independent rabies enzootics are now established in wild terrestrial carnivores (skunks in California and north-central United States, gray foxes in Texas and Arizona, and mongooses in Puerto Rico), as a consequence of different spillover events from long-term rabies enzootics associated with dogs. These preliminary results highlight the key role of dog RVs and human-dog demographics as operative factors for host shifts and disease reemergence into other important carnivore populations and highlight the need for the elimination of dog-related RVs worldwide.

Evaluation of oral rabies vaccination programs for control of rabies epizootics in coyotes and gray foxes: 1995-2003.

OBJECTIVE: To evaluate the effectiveness of intervention efforts to halt 2 wildlife rabies epizootics from 1995 through 2003, including 9 oral rabies vaccination campaigns for coyotes and 8 oral rabies vaccination campaigns for gray foxes. DESIGN: Retrospective study. ANIMALS: 98 coyotes during prevaccination surveillance and 963 coyotes and 104 nontarget animals during postvaccination surveillance in south Texas, and 699 gray foxes and 561 nontarget animals during postvaccination surveillance in west-central Texas. PROCEDURES: A recombinant-virus oral rabies vaccine in edible baits was distributed by aircraft for consumption by coyotes and gray foxes. Bait acceptance was monitored by use of microscopic analysis of tetracycline biomarker in upper canine teeth and associated bone structures in animals collected for surveillance. Serologic responses were monitered by testing sera for rabies virus-neutralizing antibodies by use of the rapid fluorescent focus inhibition test. The incidence of rabies in the distribution area was recorded via active and passive surveillance activities; tracking of rabies virus variants in confirmed rabid animals was used to determine the number and type of rabies cases before and after distributions of the vaccine. RESULTS: The expansion of both epizootics was halted as a result of the vaccine bait program. The number of laboratory-confirmed rabid animals attributable to the domestic dog-coyote rabies virus variant in south Texas declined to 0, whereas the number of laboratory-confirmed rabid animals attributable to the Texas fox rabies virus variant in west-central Texas decreased. CONCLUSIONS AND CLINICAL RELEVANCE: Data indicated that oral rabies vaccination resulted in protective immunity in a sufficient percentage of the target wildlife population to preclude propagation of the disease and provided an effective means of controlling rabies in these species.