Emerging genetic diversity of Mycoplasma gallisepticum in Mexican house finches: Evidence of possible independent spillover events

In a previous study, we reported for the first time the detection of Mycoplasma gallisepticum (MG) in Mexican house finches (Haemorhous mexicanus). Building on this finding, we explored the genetic diversity of MG, addressing the potential independent spillover events. Samples from 247 wild finches across Mexico revealed MG infection in 72 % of choanal swabs and 24 % of conjunctival swabs, with no clinical signs observed. Phylogenetic analysis identified two novel MG clades distinct from U.S. house finch-associated and poultry-associated MG strains, suggesting independent evolution within Mexico. Coinfections with diverse haplotypes were common, raising concerns about recombination and shifts in virulence. This research highlights the asymptomatic carrier state of Mexican house finches, their potential as reservoirs, and the ecological implications of pathogen spread and adaptation. These findings underscore the need for enhanced surveillance and further study on MG's dynamics in Mexican avifauna.