ABSTRACT.- Bovine babesiosis and anaplasmosis are primarily transmitted by the biological vector Rhipicephalus microplus. However, Anaplasma marginale may also be mechanically transmitted through the bites of haematophagous flies such as tabanids. While biological transmission by ticks is the predominant route for Babesia species, some reports suggest that mechanical transmission via fomites contaminated with merozoites may occur. Additionally, mechanical vectors such as tabanids may contribute to the spread of the disease. This study investigated the presence of Babesia bigemina and Babesia bovis in tabanids from three localities in Uruguay previously evaluated
for the presence of A. marginale. We performed PCR amplification targeting the Rap-1a and gp45 genes, followed by Sanger sequencing. Our findings revealed that 4.21 % of the tabanids tested positive for B. bigemina, with the highest prevalence in Tacuarembó (28.57 %), followed by Paysandú (3.22 %) and Colonia (1.75 %). Dasybasis
missionum from Tacuarembó, Poeciloderas lindneri from Paysandú, and Tabanus sp. from Colonia were positive. Additionally, a co-detection rate of 2 % with A. marginale was observed. These findings underscore the potential role of tabanids as vectors for Babesia bigemina, emphasizing the need for integrated vector control strategies in
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