During a recent lunchtime lecture hosted by the Latin American, Caribbean, and Iberian Studies Program (LACIS), Elsa Cardenas Canales shared her journey from the caves of Mexico to the laboratories of UW–Madison. She is currently pioneering a new way to manage rabies by combining laboratory and field research to vaccinate the bats themselves. While there are over 1,400 species of bats worldwide, only three are “vampires” that feed exclusively on blood, and Cardenas focuses her work on Desmodus rotundus, the common vampire bat.
These animals are highly social and cooperative, even sharing food with hungry neighbors, but they are also the primary reservoir for the rabies virus in Latin America. The virus takes a massive toll, costing the livestock industry roughly 30 million dollars annually and causing human deaths every year in remote communities. Current control methods, such as poisoning bat colonies, are often reactive and can spread the virus further by displacing infected bats.
Her ongoing research asks whether we can stop the virus at the source. During her graduate studies, Cardenas conducted a landmark experiment by capturing vampire bats in Central Mexico and transporting them to UW–Madison to test a new rabies recombinant oral vaccine. While the vaccine did not protect every bat from the disease, it revealed a significant “blocking effect.”
Of the bats that developed rabies after an experimental challenge with the virus, she found that 71% of those that did not receive the vaccine were positive for rabies in their saliva, whereas none of the vaccinated bats showed traces of the virus. This suggests that even if a vaccinated bat eventually becomes ill, it may no longer be able to pass the virus to other bats, livestock, or humans. Essentially, the vaccine turns the bat from a transmitter into a dead end for the virus.
This work has since moved back into the wild in the state of Jalisco, Mexico, where the team is tracking three bat colonies using a blend of field grit and modern technology. They use specialized traps to safely catch bats as they emerge from caves. Then, they collect samples and vaccinate bats with a commercial rabies vaccine before tracking their movements. Solar-powered antennas installed at cave entrances record exactly when each microchipped bat comes and goes, allowing researchers to monitor long-term survival and comparing treatment groups to assess how vaccination changes the population trends.
The biggest remaining challenge is vaccine delivery, as it is impossible to catch every bat in the wild for an injection. To solve this, the team is developing a “sticky” vaccine gel that takes advantage of the bat’s obsessive grooming habits. By applying the gel to just a few bats, the vaccine can spread through the colony as the animals lick and groom one another.
As Cardenas’ work continues, it offers a hopeful shift in how we coexist with misunderstood species and how understanding the natural behavior of bats leads to more effective, humane, and field-applicable solutions.
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Story by Kayla Daum