Persistence of Trichomonas gallinae in Birdseed

Trichomonas gallinae has emerged worldwide as a cause of mortality in songbirds (passerines). The congregation of numerous birds, including the reservoir hosts, pigeons and doves (columbids), at backyard feeding and watering sources has been suggested as a potential driver for the outbreaks. Evidence supporting a role for water in transmission has been established, but the role of birdseed in the transmission of trichomoniasis remained to be investigated. We assessed the survival of T. gallinae in three commercial birdseeds (mixed seed, black-oil sunflower seed, and niger seed) routinely used to attract passerine birds to local properties. Trichomonad suspensions were inoculated (low dose: 1 × 10³; high dose: 1 × 10⁵) into each of the three seed types in petri dishes, using both dry and moist (water-soaked) conditions, in triplicate. Petri dishes were incubated at 37 C and monitored for T. gallinae survival for 48 hr by wet-mount microscopy and by InPouch™ TF medium culture for 10 days. Surviving trichomonads were not detected in any of the dry birdseed treatments. In moist conditions, however, trichomonads were found to survive ≤24 hr in all three seed types and ≤48 hr in the mixed seed that contained organic debris. We demonstrate that T. gallinae has the ability to survive in moist birdseed, which suggests that public bird-feeding sites may play a significant role in the transmission of trichomoniasis.