The findings, published in the journal PLOS Neglected Tropical Diseases, show that common vampire bats in Latin America are frequently infected by Bartonella.
And their subsistence on blood creates a risk for bacterial transmission from bats to humans and livestock.
The researchers found that Bartonella infections in vampire bats are highly prevalent in Peru and Belize, and that Bartonella genotypes are distributed widely, rather than clustered geographically.
Previous studies have suggested that vampire bats may be a source of Bartonella infections among humans.
But little was known about the bats’ individual risk of infection, the genetic diversity of Bartonella bacteria in bat populations, and how the bacteria may be transmitted among bats or to other species.
Over two years, the researchers collected blood, saliva, and faecal samples from vampire bats across Belize and Peru.
Samples were then tested to ascertain how many bats were infected.
Individual risk factors for infection were identified by analysing the relationship between bat age, sex, forearm size and reproductive status.
Samples testing positive for Bartonella were then subjected to genomic sequencing and phylogenetic analysis to shed light on possible bacteria transmission routes.
Two out of every three tested bats (67 per cent) were found to be Bartonella carriers; with the highest risk of infection in large males.
Bacterial genotypes were widely distributed across Central and South America.
The researchers also investigated how Bartonella might spread between individuals.
While Bartonella spp. is often transmitted by biting arthropods, vampire bat saliva and fecal samples were also found to be positive for Bartonella, suggesting the possibility that transmission could occur through bites or environmental contamination.
While the preliminary results provide insights into the infection rate among vampire bats and the genetic diversity of bat endemic Bartonella, study lead author Doctor Daniel Becker, of Montana State University in the US, said further study is necessary.
Dr Becker added: “Given the high rates of vampire bat bites and proximity to humans, and domestic animals, such efforts to verify the possibility and frequency of oral and environmental exposures would elucidate Bartonella transmission dynamics in this common host species and the risks of cross-species transmission.”