Bat rabies and its transmission to humans and other species inother not yet identified species of the genus Lasiurus were found circulating in Mexico. Long-range dissemination patterns of rabies are not necessarily associated with migratory bat species, as in the case of rabies in Desmodus rotundus and Histiotus montanus. Human rabies was associated with vampire bat transmission in most cases, and in one case, rabies transmission from free-tailed bats was inferred. The occurrence of rabies spillover from bats to domestic animals was also demonstrated. Genetic typing of rabies viruses allowed us to distinguish trends of disease dissemination and to address, in a preliminary fashion, aspects of the complex evolution of rabies viruses in different host-reservoir species.

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Rabies remains a public health problem in the Americas because of the great diversity of wild reservoirs that maintain the virus in nature. Here we report the antigenic characterization of 254 rabies viruses isolated from 148 nonreservoir and 106 reservoir hosts collected in 27 states of Mexico. Nine out of 11 antigenic variants previously reported in the United States were detected in Mexico by using the limited panel of monoclonal antibodies donated by the Centers for Disease Control and Prevention. Some rabies virus variants were isolated from their natural reservoirs, which were also taxonomically identified. Terrestrial reservoirs included stray dogs with V1, Urocyon cineroargenteus (gray foxes) with V7, and two subspecies of Spilogale putorius (spotted skunks) with different viral variants (V8 and V10). Aerial hosts included Tadarida brasiliensis mexicana and Desmodus rotundus, which harbored V9 and V4 and harbored V11, respectively. All variants, with the exception of V9, were isolated from nonreservoir hosts, while V3, V4, and V5 were not isolated from their natural reservoirs but only from livestock. Rabies virus antigenic typing allowed us to determine rabies reservoirs and their distribution in Mexico, data which will probably improve prevention and control of the illness in humans and in the reservoir hosts.

OBJECTIVE To identify rabies virus variants (RVVs) isolated from bats and terrestrial mammals in Nuevo Leon between 2008 and 2015 and Coahuila in 2006. SAMPLE RVVs isolated from 15 bats and terrestrial mammals in Nuevo Leon and from a cow (Bos taurus) in Coahuila, along with 46 reference rabies virus sequences. PROCEDURES Antigenic characterization of the 16 isolates was performed with an indirect fluorescent antibody technique. Genomic sequencing of the nucleoprotein gene in the 16 isolates was performed with a reverse transcription PCR assay. Phylogenetic reconstruction of the 62 sequences was performed by means of Bayesian inference. RESULTS 9 isolates from bats and 1 isolate from a domestic cat that became infected as a result of contact with a Mexican free-tailed bat all clustered in the lineage associated with Lasiurus spp in the Americas or the lineage associated with Tadarida brasiliensis mexicana. An isolate from a domestic dog was identified as a variant associated with the dog-coyote lineage. The RVV isolated from a fox clustered in an Arizona fox lineage. The 3 RVVs from skunks (Mephitis macroura) were placed in a lineage with variants isolated from spotted skunks (Spilogale putorius). The RVV isolated from the cow was clustered in a lineage associated with foxes in Texas and separate from the lineage for the fox from Nuevo Leon. CONCLUSIONS AND CLINICAL RELEVANCE Results reinforced the need for Mexico to implement rabies surveillance and monitoring programs for bats and wild-living terrestrial carnivores.

In 2019, the World Health Organization (WHO) and the Pan-American Health Organization (PAHO) recognized Mexico as a country free of human rabies transmitted by dogs. Nevertheless, the sylvatic cycle remains as a public health concern in the country. Although cougars (Puma concolor) are not reservoirs of any rabies virus variant (RVV), these felines could act as vectors at the top of the food chain, and their relationships with other organisms must be considered important for the regulatory effect on their prey’s populations. In this study, genetic and antigenic characterization was performed on all cougar rabies cases diagnosed at the Rabies Laboratory Network of the Ministry of Health (RLNMH) in Mexico from 2000 to 2021. Samples from other species, a skunk, a horse (Equus caballus) (attacked by a cougar), and a gray fox (Urocyon cineroargenteus), were included as reference. Rabies cases in cougars were restricted to two Northern states of Mexico (Sonora and Chihuahua). Five out of six samples of cougars were RVV7 (Arizona gray fox RVV) and one from Sonora was RVV1. Interestingly, there is no evidence of RVV1 in dogs in the Northern states since the 1990s but skunk species now harbor this RVV1 in this region of the country.