First detection of Babesia spp. in Amblyomma mixtum from Veracruz, Mexico.

Tick-borne diseases pose a major threat to cattle production in Mexico, with bovine babesiosis caused by Babesia bigemina and Babesia bovis being among the most severe. While the invasive tick Rhipicephalus microplus is the primary vector, increasing infestations by the native Amblyomma mixtum raise concerns about its potential role in pathogen transmission. This study assessed the diversity and minimum infection rate (MIR) of piroplasmids in R. microplus and A. mixtum across 15 municipalities in Veracruz, Mexico. Ticks were collected from hosts and the environment between June 2023 and March 2024. DNA was extracted, and a fragment of the 18S gene was amplified and sequenced. The analysis identified Babesia bigemina, Babesia caballi, and Theileria equi. In A. mixtum, MIRs were 0.21% (1/481) for B. bigemina, 0.62% (3/481) for B. caballi, and 1.04% (5/481) for T. equi. In R. microplus, B. bigemina was detected with a MIR of 0.42% (2/471), while no other piroplasmids were found. These results represent the first detection of Babesia species in A. mixtum in Mexico and the Neotropical region. Although A. mixtum is not considered a traditional vector of Babesia, the findings suggest its potential epidemiological relevance. Nevertheless, detection of pathogen DNA does not confirm vector competence, only exposure to infected hosts. A key limitation was the absence of parallel host sampling, which restricts interpretation of whether DNA reflects active infection or residual blood meals. Further studies integrating host sampling and molecular analyses are needed to clarify the role of A. mixtum in piroplasmid transmission.