Rabies in Brazil now mainly transmitted by bats, studies show

Rabies is preventable, and yet it kills. A study published in August 2025 in the Revista da Sociedade Brasileira de Medicina Tropical retrospectively analysed human cases reported in Brazil between 2001 and 2025, using surveillance data, scientific literature and public health reports, to describe trends in transmission sources, changes in affected populations and challenges in prevention and treatment, particularly access to post-exposure prophylaxis.

There were 188 cases in the period, an average of 7.52 per year, most in the North and Northeast regions. Bats were the most common source of transmission, followed by dogs and non-human primates. Most cases resulted in death. Post-exposure prophylaxis was administered in most cases, but treatment may have been delayed, incomplete or initiated after symptom onset, which limited its effectiveness. Only two patients survived, both with intensive care and modified therapeutic protocols. The authors conclude that the transition from dog-mediated to bat-mediated rabies calls for enhanced surveillance and targeted prevention, and that ensuring access to prophylaxis in high-risk areas remains critical.

What made it possible to control canine rabies is described in a study published in 2023 in Pathogens. In 1973, the National Rabies Program was created through an agreement between the Ministries of Health and Agriculture, with integrated action: free post-exposure prophylaxis for people at risk, dog vaccination campaigns, a joint surveillance system and awareness-raising. Dog-mediated human cases fell from 147 to zero, and dog cases from 4,500 to 7. The challenge shifted to cases transmitted by wild animals, bats, non-human primates and wild canids. Most current human cases occur in municipalities with a tropical and subtropical moist forest biome and a Gini index above 0.5. In the multivariable analysis for 2010 to 2022, temperature was associated with more cases (odds ratio 1.739) and primary healthcare coverage was identified as protective (0.947). Half the cases are in the Northeast, and the authors see the association with temperature as a concern under climate change; they recommend keeping prophylaxis freely available, especially in remote areas of the Amazon, and expanding awareness.

Laboratory surveillance tracks that transition. A study published in 2023 in Frontiers in Veterinary Science explains that, of the Lyssavirus genotypes, only genotype 1, the classic rabies virus, circulates in Brazil, subdivided into antigenic variants maintained in independent cycles with their own hosts and distributions: AgV1 and AgV2 in dogs, AgV3 in the vampire bat Desmodus rotundus, AgV4 and AgV6 in the non-haematophagous bats Tadarida brasiliensis and Lasiurus cinereus, and variants of the marmoset Callithrix jacchus and the crab-eating fox Cerdocyon thous. Phylogenetic analysis of six surveillance genomes from the North and Northeast formed 11 monophyletic clusters, each corresponding to a variant, and placed the samples in AgV3, AgV6 and the Callithrix variant. It was the first report of AgV6 in northern Brazil. The authors call for more genomic surveillance, with more samples and greater diversity, to detect changes in geographic distribution and spillover events between hosts.

For the veterinarian, the three papers define the profession's current role in Brazilian rabies: maintaining the canine vaccination coverage that brought dog transmission to zero, taking part in surveillance of bats, herbivores and primates, and recognising that exposure to a bat, even without a visible bite, is an indication for immediate prophylaxis for the person. Post-exposure management guidance is that of Brazil's Ministry of Health, which this summary does not replace.