Feasibility of Oral Rabies Vaccination of Dogs in Mexico

Mexico has not only successfully eliminated dog-mediated human rabies in recent years, but also the last rabies case in a dog infected with the canine variant of the rabies virus was reported in 2016. Mass dog vaccination campaigns were the cornerstone of these achievements. Unfortunately, the rabies virus still circulates in wildlife and, thus, spill-over infections in humans, livestock, and pets, including dogs, still occurs. Especially dogs that cohabit at interfaces shared with wildlife, like shepherd dogs, are at risk. These dogs are often free-roaming and difficult to restrain for vaccination purposes. Oral rabies vaccination (ORV) as an alternative vaccination strategy was tested in several rural villages in Querétaro State, Mexico. Bait acceptance and immunogenicity studies were conducted to test a licensed vaccine bait in terms of attractiveness and if the oral rabies vaccine strain, SPBN GASGAS, was able to induce an adequate immune response in local dogs, respectively. Although the egg(-flavored) bait was less well accepted (68.4%) by the dogs than the two other bait types included in the study, a bait made from boiled intestine segments (71.2%) and a bait with fish meal as an attractant (72.3%), dogs offered the egg bait were more often considered successfully vaccinated. 83.3% of the dogs offered an egg bait seroconverted during the immunogenicity study. Hence, ORV can be a suitable alternative by increasing the overall vaccination coverage of dogs that cannot be easily restrained and handled for vaccination.