Coinfection of horseflies (Diptera: Tabanidae) with Babesia bigemina (Piroplasmida: Babesiidae) and Anaplasma marginale Theiler (Rickettsiales: Anaplasmataceae) in Uruguay

Bovine babesiosis and anaplasmosis are primarily transmitted by the biological vector Rhipicephalus microplus (tick). 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, implicating mechanical vectors such as tabanids in disease spread. 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 . PCR amplification targeting the Rap-1a and gp45 genes, which are specific to the merozoite stage and capable of mechanical transmission, followed by Sanger sequencing was performed. The findings revealed that 4.21% of the tabanids were infected with 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 found to be infected. Additionally, a coinfection rate of 2% with A. marginale was observed.